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Articles from 2016 In October


A Quick-and-Dirty DC Motor Controller

 A Quick-and-Dirty DC Motor Controller

Years ago my pal Steve Titus wanted to experiment with some drone rotor designs. He needed a simple motor controller that could operate from 8V to 12V and deliver amperes of current to a DC motor used in radio-controlled aircraft (figure 1).

I whipped out a design based on the classic TL494 PWM (pulse width modulation) chip (figure 2). This Texas Instruments chip is second-sourced by ON Semi, as well as others. Distributors carry the chip in small quantities with pricing from 24 cents in 1000s to 60 cents each (2016). I learned to love this chip when I consulted to Teledyne. I designed power supplies for radar jammers on F-16 fighter jets. The TL494 came in a ceramic DIP package so you could use it on mil-spec projects or for ultra-reliable industrial applications. These days I would design in an SOIC for the small size and vibration resistance. The part even comes in TSSOP for micro-miniaturization.

 You connect this motor speed control to a 12V battery. It can supply 15A of current to a DC motor.
Figure 1: You connect this motor speed control to a 12V battery. It can supply 15A of current to a DC motor.
 Texas Instruments)
Figure 2: The TL494 PWM chip is a general-purpose building block for a dozen switching power topologies. VCC can range up to 41V and it has a 5V reference output.

(Source: Texas Instruments)

To get the large amperage Steve required, I had the chip drive a large TO-3 metal-can PNP Darlington transistor that can handle 100V and 16A. Since the inductance of the motor and the wires connected to it could generate switching spikes even higher than 100V, its necessary to put a robust clamp diode across the motor (figure 3).

 A TL494 chip combined with a power Darlington transistor can deliver 16A of current to a load such as a DC motor.
Figure 3: A TL494 chip combined with a power Darlington transistor can deliver 16A of current to a load such as a DC motor.

Figure 4; The circuit applies pulses to the motor (red). This is based on the control voltage reaching a set threshold (yellow). The current into the motor gets up to 4 Amperes, and then falls through the off-time (green) . Small oscillations in current are due to the inductance of the motor and wiring interacting with the capacitance of the snubbing diode.

 The circuit applies pulses to the motor (red). This is based on the control voltage reaching a set threshold (yellow). The current into the motor gets up to 4A, and then falls through the off-time (green) . Small oscillations in current are due to the inductance of the motor and wiring interacting with the capacitance of the snubbing diode.
Figure 4: The circuit applies pulses to the motor (red). This is based on the control voltage reaching a set threshold (yellow). The current into the motor gets up to 4A, and then falls through the off-time (green) . Small oscillations in current are due to the inductance of the motor and wiring interacting with the capacitance of the snubbing diode.

You effect motor speed control by chopping the DC input voltage into variable-width pulses. I picked C3 and R5 to give an operating frequency of 8.7kHz. If the IC doesn't chop at all, it applies full battery voltage to the motor. If it applies brief narrow pulses to the motor, the average voltage is low, and the motor runs slowly (figure 4). With pulses that are vanishingly narrow there is no voltage applied to the motor, and it stops rotating. With no load on the motor, the voltage waveform can look squirrely as the back-EMF (electromotive force) of the motor creates voltage as a generator.


ESC logoDesigners & Innovators. Learn more about some of the latest designers and innovators and what they're up to at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.


 

While it might appear brutal to apply these pulses to the motor, remember that motors run on magnetism and magnetism is made with current, not voltage. So while the controller apples voltage pulses, the motor inductance turns this into current ramps that are proportional to the voltage.

For mechanical design I bought some heat sinks at a salvage yard that were already drilled to mount a TO-3 transistor. I used mica insulators and thermal grease when I mounted them. The studs from the transistor mount also spaced off and mounted the circuit card. I also picked up some 10 kilo-ohm slide pots at the salvage yard. I laid out the board in ProCAD. To make the circuit board I used pre-coated boards that I applied transparencies from my laser printer. Once the photo-resist was exposed, I plopped them in a tray of heated ferric chloride.

 My non-engineer buddy didn't think that the polarity of the input mattered. This is what happens when you hook the battery wires backwards.
Figure 5: My non-engineer buddy didn’t think that the polarity of the input mattered. This is what happens when you hook the battery wires backwards.
Regrets, I've had a few. Today I would use a surface-mount chip, and not use any tantalum or electrolytic capacitors for the best reliability. There is no other way to get the power of a TO-3 transistor on a big metal heatsink. But this was a tremendous over-design. Next time I would look at using a low-on-resistance MOSFET so I would not need the metal heatsink or the TO-3 case. A surface mount D2PAK is equivalent to a TO-220 package, and soldered to a hand-sized circuit board should be able to take away the heat. Big downside here is that the circuit board would not be isolated from the transistor drain, so maybe a TO-220 or TO-3 case with an insulator would still be a good idea.

I also would just order the PCB from a decent quick-turn fabrication shop rather than messing with photo-resist PCB material and transparencies and ferric chloride. At some point it is just easier to have the boards made, especially now that I know the basic design works OK.

Another regret I learned the hard way. I once designed a prototype with salvage yard parts to get it to the customer as soon as possible. He loved it and asked for 50 more. When I went back to the salvage yard they did not have those quantities available. They had no idea where to get more of the same parts. Now I stick with main-line distributors like Allied, so I know I can get as many parts as I need, they are not counterfeit, and my fellow engineers and hackers can order the exact same parts. Reproducibility is an essential part of the scientific method. The BOM (bill of material) below has available parts rather than the salvage yard heatsink and pot and other parts in this prototype.

My final regret is not making it really really clear to my friend Steve that everybody knows the red wire goes to the plus terminal of the 12-volt battery. He promptly hooked it up backwards and blew up one the prototypes before any use (figure 5). Thankfully I have learned to make 3 prototypes. Two that I can compare design changes and one that Marketing steals and ships to a show in Kirghistan.

Click here to download the full build instructions, including ProCAD PCB files as well as DXF and DWG versions.

Do you have a cool, original, homemade gadget collecting dust in your garage? Give us the details at DesignNews.com/GF, and you may receive $500 and entry into our Gadget Freak of the Year contest!

DC motor controller PARTS LIST

     

Component reference

Component/Material

Cost

Source

Motor

Motor, DC Ceramic Permanent Magnet, Long Stack - Ball Bearings, 24 VDC

$127.07

Allied Stock #: 70217726

Q1

TRANSISTOR, NTE250 PNP SILICON DARLINGTON 100V IC=16A TO-3 CASE

$8.74

Allied Stock#: 70215870

Q1 insulator

RS Pro Heatsink Transistor Mount Kit For TO-3

$1.83

Allied Stock#: 70637780

Q1 grease

Aavid Thermalloy Thermal Grease, 2 Oz., Thermalcote

$10.82

Allied Stock#: 70115245

PCB

MG Chemicals Board; Copper Clad; 9 x 6 in; 1/16 thk; double sided; presensitized

$21.50 (makes 4 PCBs)

Allied Stock#: 70125853

PCB etchant

MG Chemicals Chemical; Ferric Chloride Copper Etchant; 17oz liquid

$9.25

Allied Stock#: 70125782

D1

Diode, MR752 6A 200V Silicon Rectifier

$1.14

Allied Stock#: 70911267

U1

TL494 SWITCHMODE Pulse Width Modulation (note- SOIC package!)

$0.27 ea (20 min)

Allied Stock#: 70341601

Pot1

Bourns Potentiometer, Panel Control, Carbon, 100mm, 10 Kilohms, 20%

$3.91

Allied Stock#: 70155184

Pot knob

RS Pro Slide Knob; Body: Black with a White Indicator; 1.2x4mm Shaft

$0.39

Allied Stock#: 70644546

Heatsink

Wakefield 423K Heatsink; TO-3; 47C @ 50W; 2.625 in.; 0.5C/W;

$20.79

Allied Stock#: 70236723

C1

Capacitor; Tantalum; 33uF; Tap Series; Radial; Case J; 10%; 25V; 33VDC; 1.2 Ohms ESR

$2.18

Allied Stock#: 70195926

C2

Capacitor; Ceramic; Cap 1uF; Tol 10%; Radial; Vol-Rtg 25V; Dielectric X7R

$0.770

Allied Stock#: 70096303

R1. R2

Vishay Dale Resistor; Metal Film; 133 Ohms; 0.5 W; Tol 1%; Axial; Military (qty 2)

$0.44 ea

Allied Stock#: 70200270

R3

RESISTOR METAL FILM 1/4W 3.16K OHM 1% AXIAL LEAD

$0.05

Allied Stock#: 70722839

R4

Resistor; Metal Film; Res 1.13 Kilohms; Pwr-Rtg 0.125 W; Tol 1%; Axial

$1.02

Allied Stock#: 70205979

C3

Nichicon Capacitor Polyester Film Cap 0.01uF 100V 10% Radial 6.5X10.5 LS 5mm

$0.142

Allied Stock#: 70188286

R5

Vishay Dale Resistor; Metal Film; Res 19.1 Kilohms; Pwr-Rtg 0.125 W; Tol 1%; Axial; Military

$0.09

Allied Stock#: 70200553

J1, J2

TE Connectivity UNIV M-N-L HEADER, 02P UMNL HDR ASSY R/A 94VO LF

$1.66 ea

(qty 2)

Allied Stock#: 70087875

P1, P2

TE Connectivity Connector, Soft Shell; Universal MATE-N-LOK; 2; Plug; Nylon; White; 19 A

$0.25 ea

(qty 2)

Allied Stock#: 70083521

P1, P2 contacts

TE Connectivity Universal MATE-N-LOK II Socket Contact, 24-18AWG, Gold (30) over Nickel

$1.26 ea

(qty 4)

Allied Stock#: 70041811

P3

Pomona Electronics Banana Jack; Banana Plug; 15 A; Black; Beryllium Copper; 5000 Vrms

$5.24

Allied Stock#: 70197210

P4

Pomona Electronics Banana Jack; Banana Plug; 15 A; Red; Beryllium Copper; 5000 Vrms

$5.24

Allied Stock#: 70197211

Q1 screws

APM Hexseal Hardware, Phillips Pan Head Seelskrew, 1 Inch, 6-32 Thread Size, SS

$0.51 ea

(qty 2)

Allied Stock#: 70156385

J1, J2 screws

APM Hexseal Hardware, Phillips Pan Head Seelskrew, 1/2 Inch, 6-32 Thread Size, SS

$0.43 ea

(qty 4)

Allied Stock#: 70156382

Q1, J1, J2 nuts

Keystone Electronics Nut; Hex 6-32 Threaded ; Steel; Machined; OD .250

$0.070 ea

(qty 10)

Allied Stock#: 70279752

Q1, J1, J2 lock washers

Keystone Electronics Terminal Lug; Lockwasher; Brass, Tin Plate; Length .875; Hole Size #6

$0.120 ea

(qty 6)

Allied Stock#: 70386216

[All images via Paul Rako, unless otherwise noted]

Better Than Harvard: 15 Best Buys in Engineering Education

<p>The University of California-Berkeley’s engineering program is ranked third in the country, compared to Harvard’s 28th and Yale’s 37th, according to US News & World Report’s Best Colleges. In-state tuition is $13,431 and out-of-state is $38K. It’s also rated in the top five in eight engineering specialties, including chemical, civil, computer, electrical, environmental, industrial, materials, and mechanical engineering. As an added bonus, it’s a stone’s throw from Silicon Valley.</p><p>(Source: By brainchildvn on Flickr - Flickr, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=6638057)</p>

Harvard and Yale are regarded as the national gold standard in college education, but not in engineering. According to US News & World Report’s new 2017 Best Colleges, 15 public engineering programs are more highly ranked. And while the tuition at Harvard and Yale exceeds $47,000 a year, state schools can be had for as little as $10,000.

Don’t misunderstand -- Harvard, Yale, and other Ivies have great engineering programs and are deserving of the avalanche of accolades they’re received over the years. But we've collected information about major universities from California to Maryland that offer bachelor's, master's, and PhDs in engineering. And they’re every bit as good, if not better, than those gold standard colleges.

Better Than Harvard: 15 Best Buys in Engineering Education

Harvard and Yale are regarded as the national gold standard in college education, but not in engineering. According to US News & World Report’s new 2017 Best Colleges, 15 public engineering programs are more highly ranked. And while the tuition at Harvard and Yale exceeds $47,000 a year, state schools can be had for as little as $10,000.

Don’t misunderstand -- Harvard, Yale, and other Ivies have great engineering programs and are deserving of the avalanche of accolades they’re received over the years. But we've collected information about major universities from California to Maryland that offer bachelor's, master's, and PhDs in engineering. And they’re every bit as good, if not better, than those gold standard colleges.

Click on the image below to see who they are and how they excel.

The University of California-Berkeley’s engineering program is ranked third in the country, compared to Harvard’s 28th and Yale’s 37th, according to US News & World Report’s Best Colleges. In-state tuition is $13,431 and out-of-state is $38K. It’s also rated in the top five in eight engineering specialties, including chemical, civil, computer, electrical, environmental, industrial, materials, and mechanical engineering. As an added bonus, it’s a stone’s throw from Silicon Valley.

(Source: By brainchildvn on Flickr - Flickr, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=6638057)


ESC logoDesign Technologies. Learn more about electronics and security at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.





Senior technical editor Chuck Murray has been writing about technology for 32 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and autos.

A Quick-and-Dirty DC Motor Controller

Years ago my pal Steve Titus wanted to experiment with some drone rotor designs. He needed a simple motor controller that could operate from 8V to 12V and deliver amperes of current to a DC motor used in radio-controlled aircraft (figure 1).

I whipped out a design based on the classic TL494 PWM (pulse width modulation) chip (figure 2). This Texas Instruments chip is second-sourced by ON Semi, as well as others. Distributors carry the chip in small quantities with pricing from 24 cents in 1000s to 60 cents each (2016). I learned to love this chip when I consulted to Teledyne. I designed power supplies for radar jammers on F-16 fighter jets. The TL494 came in a ceramic DIP package so you could use it on mil-spec projects or for ultra-reliable industrial applications. These days I would design in an SOIC for the small size and vibration resistance. The part even comes in TSSOP for micro-miniaturization.

Figure 1: You connect this motor speed control to a 12V battery. It can supply 15A of current to a DC motor.

Figure 2: The TL494 PWM chip is a general-purpose building block for a dozen switching power topologies. VCC can range up to 41V and it has a 5V reference output.

(Source: Texas Instruments)

To get the large amperage Steve required, I had the chip drive a large TO-3 metal-can PNP Darlington transistor that can handle 100V and 16A. Since the inductance of the motor and the wires connected to it could generate switching spikes even higher than 100V, its necessary to put a robust clamp diode across the motor (figure 3).

Figure 3: A TL494 chip combined with a power Darlington transistor can deliver 16A of current to a load such as a DC motor.

Figure 4; The circuit applies pulses to the motor (red). This is based on the control voltage reaching a set threshold (yellow). The current into the motor gets up to 4 Amperes, and then falls through the off-time (green) . Small oscillations in current are due to the inductance of the motor and wiring interacting with the capacitance of the snubbing diode.

Figure 4: The circuit applies pulses to the motor (red). This is based on the control voltage reaching a set threshold (yellow). The current into the motor gets up to 4A, and then falls through the off-time (green) . Small oscillations in current are due to the inductance of the motor and wiring interacting with the capacitance of the snubbing diode.

You effect motor speed control by chopping the DC input voltage into variable-width pulses. I picked C3 and R5 to give an operating frequency of 8.7kHz. If the IC doesn't chop at all, it applies full battery voltage to the motor. If it applies brief narrow pulses to the motor, the average voltage is low, and the motor runs slowly (figure 4). With pulses that are vanishingly narrow there is no voltage applied to the motor, and it stops rotating. With no load on the motor, the voltage waveform can look squirrely as the back-EMF (electromotive force) of the motor creates voltage as a generator.


ESC logoDesigners & Innovators. Learn more about some of the latest designers and innovators and what they're up to at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.



While it might appear brutal to apply these pulses to the motor, remember that motors run on magnetism and magnetism is made with current, not voltage. So while the controller apples voltage pulses, the motor inductance turns this into current ramps that are proportional to the voltage.

For mechanical design I bought some heat sinks at a salvage yard that were already drilled to mount a TO-3 transistor. I used mica insulators and thermal grease when I mounted them. The studs from the transistor mount also spaced off and mounted the circuit card. I also picked up some 10 kilo-ohm slide pots at the salvage yard. I laid out the board in ProCAD. To make the circuit board I used pre-coated boards that I applied transparencies from my laser printer. Once the photo-resist was exposed, I plopped them in a tray of heated ferric chloride.

Figure 5: My non-engineer buddy didn’t think that the polarity of the input mattered. This is what happens when you hook the battery wires backwards.

Regrets, I've had a few. Today I would use a surface-mount chip, and not use any tantalum or electrolytic capacitors for the best reliability. There is no other way to get the power of a TO-3 transistor on a big metal heatsink. But this was a tremendous over-design. Next time I would look at using a low-on-resistance MOSFET so I would not need the metal heatsink or the TO-3 case. A surface mount D2PAK is equivalent to a TO-220 package, and soldered to a hand-sized circuit board should be able to take away the heat. Big downside here is that the circuit board would not be isolated from the transistor drain, so maybe a TO-220 or TO-3 case with an insulator would still be a good idea.

I also would just order the PCB from a decent quick-turn fabrication shop rather than messing with photo-resist PCB material and transparencies and ferric chloride. At some point it is just easier to have the boards made, especially now that I know the basic design works OK.

Another regret I learned the hard way. I once designed a prototype with salvage yard parts to get it to the customer as soon as possible. He loved it and asked for 50 more. When I went back to the salvage yard they did not have those quantities available. They had no idea where to get more of the same parts. Now I stick with main-line distributors like Allied, so I know I can get as many parts as I need, they are not counterfeit, and my fellow engineers and hackers can order the exact same parts. Reproducibility is an essential part of the scientific method. The BOM (bill of material) below has available parts rather than the salvage yard heatsink and pot and other parts in this prototype.

My final regret is not making it really really clear to my friend Steve that everybody knows the red wire goes to the plus terminal of the 12-volt battery. He promptly hooked it up backwards and blew up one the prototypes before any use (figure 5). Thankfully I have learned to make 3 prototypes. Two that I can compare design changes and one that Marketing steals and ships to a show in Kirghistan.

Click here to download the full build instructions, including ProCAD PCB files as well as DXF and DWG versions.

Do you have a cool, original, homemade gadget collecting dust in your garage? Give us the details at DesignNews.com/GF, and you may receive $500 and entry into our Gadget Freak of the Year contest!

DC motor controller PARTS LIST

Component reference

Component/Material

Cost

Source

Motor

Motor, DC Ceramic Permanent Magnet, Long Stack - Ball Bearings, 24 VDC

$127.07

Allied Stock #: 70217726

Q1

TRANSISTOR, NTE250 PNP SILICON DARLINGTON 100V IC=16A TO-3 CASE

$8.74

Allied Stock#: 70215870

Q1 insulator

RS Pro Heatsink Transistor Mount Kit For TO-3

$1.83

Allied Stock#: 70637780

Q1 grease

Aavid Thermalloy Thermal Grease, 2 Oz., Thermalcote

$10.82

Allied Stock#: 70115245

PCB

MG Chemicals Board; Copper Clad; 9 x 6 in; 1/16 thk; double sided; presensitized

$21.50 (makes 4 PCBs)

Allied Stock#: 70125853

PCB etchant

MG Chemicals Chemical; Ferric Chloride Copper Etchant; 17oz liquid

$9.25

Allied Stock#: 70125782

D1

Diode, MR752 6A 200V Silicon Rectifier

$1.14

Allied Stock#: 70911267

U1

TL494 SWITCHMODE Pulse Width Modulation (note- SOIC package!)

$0.27 ea (20 min)

Allied Stock#: 70341601

Pot1

Bourns Potentiometer, Panel Control, Carbon, 100mm, 10 Kilohms, 20%

$3.91

Allied Stock#: 70155184

Pot knob

RS Pro Slide Knob; Body: Black with a White Indicator; 1.2x4mm Shaft

$0.39

Allied Stock#: 70644546

Heatsink

Wakefield 423K Heatsink; TO-3; 47C @ 50W; 2.625 in.; 0.5C/W;

$20.79

Allied Stock#: 70236723

C1

Capacitor; Tantalum; 33uF; Tap Series; Radial; Case J; 10%; 25V; 33VDC; 1.2 Ohms ESR

$2.18

Allied Stock#: 70195926

C2

Capacitor; Ceramic; Cap 1uF; Tol 10%; Radial; Vol-Rtg 25V; Dielectric X7R

$0.770

Allied Stock#: 70096303

R1. R2

Vishay Dale Resistor; Metal Film; 133 Ohms; 0.5 W; Tol 1%; Axial; Military (qty 2)

$0.44 ea

Allied Stock#: 70200270

R3

RESISTOR METAL FILM 1/4W 3.16K OHM 1% AXIAL LEAD

$0.05

Allied Stock#: 70722839

R4

Resistor; Metal Film; Res 1.13 Kilohms; Pwr-Rtg 0.125 W; Tol 1%; Axial

$1.02

Allied Stock#: 70205979

C3

Nichicon Capacitor Polyester Film Cap 0.01uF 100V 10% Radial 6.5X10.5 LS 5mm

$0.142

Allied Stock#: 70188286

R5

Vishay Dale Resistor; Metal Film; Res 19.1 Kilohms; Pwr-Rtg 0.125 W; Tol 1%; Axial; Military

$0.09

Allied Stock#: 70200553

J1, J2

TE Connectivity UNIV M-N-L HEADER, 02P UMNL HDR ASSY R/A 94VO LF

$1.66 ea

(qty 2)

Allied Stock#: 70087875

P1, P2

TE Connectivity Connector, Soft Shell; Universal MATE-N-LOK; 2; Plug; Nylon; White; 19 A

$0.25 ea

(qty 2)

Allied Stock#: 70083521

P1, P2 contacts

TE Connectivity Universal MATE-N-LOK II Socket Contact, 24-18AWG, Gold (30) over Nickel

$1.26 ea

(qty 4)

Allied Stock#: 70041811

P3

Pomona Electronics Banana Jack; Banana Plug; 15 A; Black; Beryllium Copper; 5000 Vrms

$5.24

Allied Stock#: 70197210

P4

Pomona Electronics Banana Jack; Banana Plug; 15 A; Red; Beryllium Copper; 5000 Vrms

$5.24

Allied Stock#: 70197211

Q1 screws

APM Hexseal Hardware, Phillips Pan Head Seelskrew, 1 Inch, 6-32 Thread Size, SS

$0.51 ea

(qty 2)

Allied Stock#: 70156385

J1, J2 screws

APM Hexseal Hardware, Phillips Pan Head Seelskrew, 1/2 Inch, 6-32 Thread Size, SS

$0.43 ea

(qty 4)

Allied Stock#: 70156382

Q1, J1, J2 nuts

Keystone Electronics Nut; Hex 6-32 Threaded ; Steel; Machined; OD .250

$0.070 ea

(qty 10)

Allied Stock#: 70279752

Q1, J1, J2 lock washers

Keystone Electronics Terminal Lug; Lockwasher; Brass, Tin Plate; Length .875; Hole Size #6

$0.120 ea

(qty 6)

Allied Stock#: 70386216

[All images via Paul Rako, unless otherwise noted]

A Quick-and-Dirty DC Motor Controller

A Quick-and-Dirty DC Motor Controller

Years ago my pal Steve Titus wanted to experiment with some drone rotor designs. He needed a simple motor controller that could operate from 8V to 12V and deliver amperes of current to a DC motor used in radio-controlled aircraft (figure 1).

I whipped out a design based on the classic TL494 PWM (pulse width modulation) chip (figure 2). This Texas Instruments chip is second-sourced by ON Semi, as well as others. Distributors carry the chip in small quantities with pricing from 24 cents in 1000s to 60 cents each (2016). I learned to love this chip when I consulted to Teledyne. I designed power supplies for radar jammers on F-16 fighter jets. The TL494 came in a ceramic DIP package so you could use it on mil-spec projects or for ultra-reliable industrial applications. These days I would design in an SOIC for the small size and vibration resistance. The part even comes in TSSOP for micro-miniaturization.

To get the large amperage Steve required, I had the chip drive a large TO-3 metal-can PNP Darlington transistor that can handle 100V and 16A. Since the inductance of the motor and the wires connected to it could generate switching spikes even higher than 100V, its necessary to put a robust clamp diode across the motor (figure 3).

Figure 4; The circuit applies pulses to the motor (red). This is based on the control voltage reaching a set threshold (yellow). The current into the motor gets up to 4 Amperes, and then falls through the off-time (green) . Small oscillations in current are due to the inductance of the motor and wiring interacting with the capacitance of the snubbing diode.

You effect motor speed control by chopping the DC input voltage into variable-width pulses. I picked C3 and R5 to give an operating frequency of 8.7kHz. If the IC doesn't chop at all, it applies full battery voltage to the motor. If it applies brief narrow pulses to the motor, the average voltage is low, and the motor runs slowly (figure 4). With pulses that are vanishingly narrow there is no voltage applied to the motor, and it stops rotating. With no load on the motor, the voltage waveform can look squirrely as the back-EMF (electromotive force) of the motor creates voltage as a generator.


ESC logoDesigners & Innovators. Learn more about some of the latest designers and innovators and what they're up to at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.



While it might appear brutal to apply these pulses to the motor, remember that motors run on magnetism and magnetism is made with current, not voltage. So while the controller apples voltage pulses, the motor inductance turns this into current ramps that are proportional to the voltage.

For mechanical design I bought some heat sinks at a salvage yard that were already drilled to mount a TO-3 transistor. I used mica insulators and thermal grease when I mounted them. The studs from the transistor mount also spaced off and mounted the circuit card. I also picked up some 10 kilo-ohm slide pots at the salvage yard. I laid out the board in ProCAD. To make the circuit board I used pre-coated boards that I applied transparencies from my laser printer. Once the photo-resist was exposed, I plopped them in a tray of heated ferric chloride.

Regrets, I've had a few. Today I would use a surface-mount chip, and not use any tantalum or electrolytic capacitors for the best reliability. There is no other way to get the power of a TO-3 transistor on a big metal heatsink. But this was a tremendous over-design. Next time I would look at using a low-on-resistance MOSFET so I would not need the metal heatsink or the TO-3 case. A surface mount D2PAK is equivalent to a TO-220 package, and soldered to a hand-sized circuit board should be able to take away the heat. Big downside here is that the circuit board would not be isolated from the transistor drain, so maybe a TO-220 or TO-3 case with an insulator would still be a good idea.

I also would just order the PCB from a decent quick-turn fabrication shop rather than messing with photo-resist PCB material and transparencies and ferric chloride. At some point it is just easier to have the boards made, especially now that I know the basic design works OK.

Another regret I learned the hard way. I once designed a prototype with salvage yard parts to get it to the customer as soon as possible. He loved it and asked for 50 more. When I went back to the salvage yard they did not have those quantities available. They had no idea where to get more of the same parts. Now I stick with main-line distributors like Allied, so I know I can get as many parts as I need, they are not counterfeit, and my fellow engineers and hackers can order the exact same parts. Reproducibility is an essential part of the scientific method. The BOM (bill of material) below has available parts rather than the salvage yard heatsink and pot and other parts in this prototype.

My final regret is not making it really really clear to my friend Steve that everybody knows the red wire goes to the plus terminal of the 12-volt battery. He promptly hooked it up backwards and blew up one the prototypes before any use (figure 5). Thankfully I have learned to make 3 prototypes. Two that I can compare design changes and one that Marketing steals and ships to a show in Kirghistan.

Click here to download the full build instructions, including ProCAD PCB files as well as DXF and DWG versions.

Do you have a cool, original, homemade gadget collecting dust in your garage? Give us the details at DesignNews.com/GF, and you may receive $500 and entry into our Gadget Freak of the Year contest!

DC motor controller PARTS LIST

Component reference

Component/Material

Cost

Source

Motor

Motor, DC Ceramic Permanent Magnet, Long Stack - Ball Bearings, 24 VDC

$127.07

Allied Stock #: 70217726

Q1

TRANSISTOR, NTE250 PNP SILICON DARLINGTON 100V IC=16A TO-3 CASE

$8.74

Allied Stock#: 70215870

Q1 insulator

RS Pro Heatsink Transistor Mount Kit For TO-3

$1.83

Allied Stock#: 70637780

Q1 grease

Aavid Thermalloy Thermal Grease, 2 Oz., Thermalcote

$10.82

Allied Stock#: 70115245

PCB

MG Chemicals Board; Copper Clad; 9 x 6 in; 1/16 thk; double sided; presensitized

$21.50 (makes 4 PCBs)

Allied Stock#: 70125853

PCB etchant

MG Chemicals Chemical; Ferric Chloride Copper Etchant; 17oz liquid

$9.25

Allied Stock#: 70125782

D1

Diode, MR752 6A 200V Silicon Rectifier

$1.14

Allied Stock#: 70911267

U1

TL494 SWITCHMODE Pulse Width Modulation (note- SOIC package!)

$0.27 ea (20 min)

Allied Stock#: 70341601

Pot1

Bourns Potentiometer, Panel Control, Carbon, 100mm, 10 Kilohms, 20%

$3.91

Allied Stock#: 70155184

Pot knob

RS Pro Slide Knob; Body: Black with a White Indicator; 1.2x4mm Shaft

$0.39

Allied Stock#: 70644546

Heatsink

Wakefield 423K Heatsink; TO-3; 47C @ 50W; 2.625 in.; 0.5C/W;

$20.79

Allied Stock#: 70236723

C1

Capacitor; Tantalum; 33uF; Tap Series; Radial; Case J; 10%; 25V; 33VDC; 1.2 Ohms ESR

$2.18

Allied Stock#: 70195926

C2

Capacitor; Ceramic; Cap 1uF; Tol 10%; Radial; Vol-Rtg 25V; Dielectric X7R

$0.770

Allied Stock#: 70096303

R1. R2

Vishay Dale Resistor; Metal Film; 133 Ohms; 0.5 W; Tol 1%; Axial; Military (qty 2)

$0.44 ea

Allied Stock#: 70200270

R3

RESISTOR METAL FILM 1/4W 3.16K OHM 1% AXIAL LEAD

$0.05

Allied Stock#: 70722839

R4

Resistor; Metal Film; Res 1.13 Kilohms; Pwr-Rtg 0.125 W; Tol 1%; Axial

$1.02

Allied Stock#: 70205979

C3

Nichicon Capacitor Polyester Film Cap 0.01uF 100V 10% Radial 6.5X10.5 LS 5mm

$0.142

Allied Stock#: 70188286

R5

Vishay Dale Resistor; Metal Film; Res 19.1 Kilohms; Pwr-Rtg 0.125 W; Tol 1%; Axial; Military

$0.09

Allied Stock#: 70200553

J1, J2

TE Connectivity UNIV M-N-L HEADER, 02P UMNL HDR ASSY R/A 94VO LF

$1.66 ea

(qty 2)

Allied Stock#: 70087875

P1, P2

TE Connectivity Connector, Soft Shell; Universal MATE-N-LOK; 2; Plug; Nylon; White; 19 A

$0.25 ea

(qty 2)

Allied Stock#: 70083521

P1, P2 contacts

TE Connectivity Universal MATE-N-LOK II Socket Contact, 24-18AWG, Gold (30) over Nickel

$1.26 ea

(qty 4)

Allied Stock#: 70041811

P3

Pomona Electronics Banana Jack; Banana Plug; 15 A; Black; Beryllium Copper; 5000 Vrms

$5.24

Allied Stock#: 70197210

P4

Pomona Electronics Banana Jack; Banana Plug; 15 A; Red; Beryllium Copper; 5000 Vrms

$5.24

Allied Stock#: 70197211

Q1 screws

APM Hexseal Hardware, Phillips Pan Head Seelskrew, 1 Inch, 6-32 Thread Size, SS

$0.51 ea

(qty 2)

Allied Stock#: 70156385

J1, J2 screws

APM Hexseal Hardware, Phillips Pan Head Seelskrew, 1/2 Inch, 6-32 Thread Size, SS

$0.43 ea

(qty 4)

Allied Stock#: 70156382

Q1, J1, J2 nuts

Keystone Electronics Nut; Hex 6-32 Threaded ; Steel; Machined; OD .250

$0.070 ea

(qty 10)

Allied Stock#: 70279752

Q1, J1, J2 lock washers

Keystone Electronics Terminal Lug; Lockwasher; Brass, Tin Plate; Length .875; Hole Size #6

$0.120 ea

(qty 6)

Allied Stock#: 70386216

[All images via Paul Rako, unless otherwise noted]

ORNL and Students 3D Print Excavator Parts

Researchers at Oak Ridge National Laboratory (ORNL) are working with university students and industry partners to design and 3D print large-scale parts for a heavy construction machine. The project aims at accomplishing several goals, including reducing production time and overall cost of making low-volume, high-complexity components for the construction industry.

The completed excavator prototype is known as Project AME (Additive Manufactured Excavator). It will have three large 3D-printed components: the operator cab, the stick, and a heat exchanger. A student engineering team from the University of Illinois at Urbana-Champaign designed the cab. It will be printed on the same Big Area Additive Manufacturing (BAAM) machine that printed a replica of the historic Shelby Cobra sports car in only six weeks using carbon fiber-reinforced ABS composites.

The completed Project AME (Additive Manufactured Excavator) excavator prototype will have three large 3D-printed components: the operator cab, the stick, and a heat exchanger. The cab, shown here, was designed by a University of Illinois at Urbana-Champaign student engineering team and printed at Oak Ridge National Laboratory's Manufacturing Demonstration Facility using carbon fiber-reinforced ABS plastic.

Another student group at the University of Minnesota is designing the heat exchanger, ORNL's Manufacturing Systems Research group leader, Lonnie Love, told Design News. "For that part, which is metal, we'll use the Concept Laser powder bed system," he said.

The excavator's stick, a large hydraulically articulated arm, or boom, is being designed by a third group of students, at the Georgia Institute of Technology. One student in this group worked on this project while an intern at ORNL. That team is using the design freedom of additive manufacturing (AM) to integrate the hydraulics into the boom, and make the part more lightweight, Love said. It will be fabricated using a Wolf System, a machine that uses a freeform technique using robotics to print large-scale metal components. That machine was installed recently at ORNL.

Oak Ridge National Laboratory's Lonnie Love hosted the University of Illinois at Urbana-Champaign student engineering team at the lab's Manufacturing Demonstration Facility. The students, with Love (third from left), stand inside the Big Area Additive Manufacturing (BAAM) system that will print their award-winning excavator cab design.

During 3D printing of both the excavator's heat exchanger and its boom, the teams will have an opportunity to develop processes even further that will improve material performance and printability. They also expect to validate models that will show how to adapt designs to reduce residual stress and distortion.


ESC logoDesigners & Innovators Learn more about some of the latest designers and innovators and what they're up to at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.



Once the excavator prototype is complete, it will be displayed at the IFPE and CONEXPO-CON/AGG shows in Las Vegas in March 2017. The plan is to 3D print a second excavator cab live at the event, Love told us.

Although 3D printing might not become common in the construction industry for excavators and other vehicles, "additive manufacturing can be used to print components on demand, which could potentially eliminate the need for mass storage, organization, and transportation," Love said in a press release.

ORNL's partners for Project AME include the Association of Equipment Manufacturers, the National Fluid Power Association, the Center for Compact and Efficient Fluid Power, and the National Science Foundation. The project was funded by the Department of Energy's Office of Energy Efficiency and Renewable Energy -- Advanced Manufacturing Office.

[images via ORNL]

Ann R. Thryft is senior technical editor, materials & assembly, for Design News. She's been writing about manufacturing- and electronics-related technologies for 29 years, covering manufacturing materials & processes, alternative energy, and robotics. In the past, she's also written about machine vision and all kinds of communications.

ORNL and Students 3D Print Excavator Parts

ORNL and Students 3D Print Excavator Parts

Researchers at Oak Ridge National Laboratory (ORNL) are working with university students and industry partners to design and 3D print large-scale parts for a heavy construction machine. The project aims at accomplishing several goals, including reducing production time and overall cost of making low-volume, high-complexity components for the construction industry.

The completed excavator prototype is known as Project AME (Additive Manufactured Excavator). It will have three large 3D-printed components: the operator cab, the stick, and a heat exchanger. A student engineering team from the University of Illinois at Urbana-Champaign designed the cab. It will be printed on the same Big Area Additive Manufacturing (BAAM) machine that printed a replica of the historic Shelby Cobra sports car in only six weeks using carbon fiber-reinforced ABS composites.

Another student group at the University of Minnesota is designing the heat exchanger, ORNL's Manufacturing Systems Research group leader, Lonnie Love, told Design News. "For that part, which is metal, we'll use the Concept Laser powder bed system," he said.

The excavator's stick, a large hydraulically articulated arm, or boom, is being designed by a third group of students, at the Georgia Institute of Technology. One student in this group worked on this project while an intern at ORNL. That team is using the design freedom of additive manufacturing (AM) to integrate the hydraulics into the boom, and make the part more lightweight, Love said. It will be fabricated using a Wolf System, a machine that uses a freeform technique using robotics to print large-scale metal components. That machine was installed recently at ORNL.

During 3D printing of both the excavator's heat exchanger and its boom, the teams will have an opportunity to develop processes even further that will improve material performance and printability. They also expect to validate models that will show how to adapt designs to reduce residual stress and distortion.


ESC logoDesigners & Innovators Learn more about some of the latest designers and innovators and what they're up to at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.



Once the excavator prototype is complete, it will be displayed at the IFPE and CONEXPO-CON/AGG shows in Las Vegas in March 2017. The plan is to 3D print a second excavator cab live at the event, Love told us.

Although 3D printing might not become common in the construction industry for excavators and other vehicles, "additive manufacturing can be used to print components on demand, which could potentially eliminate the need for mass storage, organization, and transportation," Love said in a press release.

ORNL's partners for Project AME include the Association of Equipment Manufacturers, the National Fluid Power Association, the Center for Compact and Efficient Fluid Power, and the National Science Foundation. The project was funded by the Department of Energy's Office of Energy Efficiency and Renewable Energy -- Advanced Manufacturing Office.

[images via ORNL]

Ann R. Thryft is senior technical editor, materials & assembly, for Design News. She's been writing about manufacturing- and electronics-related technologies for 29 years, covering manufacturing materials & processes, alternative energy, and robotics. In the past, she's also written about machine vision and all kinds of communications.

13 Horror Movies About Technology Gone Wrong

Technology gone wrong has made great fodder for scary tales for centuries -- since stories like Frankenstein and The Strange Case of Dr Jekyll and Mr Hyde first appeared in the 19th century. Even the most benevolent technology comes with its own built-in fears and movie makers are always ready to take advantage. And while we like to believe all of our scientists and researchers are acting with the best of intentions, you just can't deny that some technologies will have unexpected consequences or are even just downright creepy to begin with.

So if you're looking to get your horror and technology fix this Halloween, here's our list of 13 of the most horrific technology-gone-wrong movies, presented alongside some of the real-world technologies that could one day make our nightmares a reality. If you don't think autonomous cars, augmented reality, teleportation, and artificial intelligence could possibly be scary, these movies will change your mind.

Any favorites we missed on the list? Share yours in the comments!

No list of science fiction horror would be complete without the granddaddy of them all. We all know some variation of the story: A mad scientist brings a monster, made of an assortment of human corpses, to life. The means vary depending on the source (Mary Shelly's novel is vague about it while movies have used a variety of means from lightening to electric eels) and history has more than one example of scientists trying to reanimate the dead.

But there's a new wrinkle that Mary Shelly could never have thought of – creating an artificial life with computers instead of biology. That's the premise of The Blue Brain Project, which was started in May 2005 by the Brain and Mind Institute of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. The goal of the project is to eventually use supercomputers to create a synthetic human brain capable of everything its biological counterpart is. The project is still in its infancy, but in an October 2015 article in the journal Nature researchers with the project announced they had been able to successful simulate a very small part of a rat's cortex. Sympathetic monsters here we come! (Image source: Universal Pictures)

Chris Wiltz is the Managing Editor of Design News  


ESC logoDesigners & Innovators. Learn more about some of the latest designers and innovators and what they're up to at ESC Silicon Valley, Dec. 6-8, 2016 in San Jose, Calif. Register here for the event, hosted by Design News’ parent company, UBM.



The Story Behind Hacking the Jeep

When Wired ran the story about Charlie Miller and Chris Valasek hacking a Jeep and running it off the road last year, it was not some snappy lark. The process took several months of painstaking effort to learn the vehicle’s information system and crack the code. In the end, the two scientists (Miller has a PhD in mathematics and Valasek has a degree in computer science) figured out they had to enter the Jeep’s CAN Bus brains to reach the steering and the brakes.

Charlie Miller speaking at the 2016 ARM TechCon conference.

At a keynote talk at the ARM TechCon conference this week, Miller offered the details of the hacking and warned that vehicles will not be cyber-safe anytime soon. He started off explaining that car hacking is very recent, since hackers didn’t realize cars were vulnerable until just the last few years. “Hacking cars started in 2010. Until then, people didn’t realize there are computers in their cars. They didn’t realize that if you plug into a car, you can cut the brake lines,” said Miller, who works as an engineer at Uber. “I read the papers about the first hackings and decided this was something I wanted to do.”

Miller noted that the first car hackers entered through OnStar. “OnStar is a service that allows you to call for help. They dialed into OnStar and took over the car,” he said. “They did it in a testing track. They could lock up individual brakes, and they were able to stop the car. They didn’t release any details, so I didn't have anything to go on. They didn’t even reveal what type of car they used.”

For their first hacking, Miller and Valasek used a Ford Escape and a Toyota Prius. “We went to a car dealer and bought the cars. We hacked in and found we could control the keys and the locks,” said Miller. “We were able to control the steering. It was inconsistent, but we could do it sometimes. It would take 30 minutes.”

The Vulnerabilities Are in the Features

Through the process of hacking, Miller and Valasek learned how the data systems in cars are put together. They discovered the importance of the CAN Bus. “Cars have changed. As you add more and more features, you have all this wire in the car. That’s weight and cost, so car companies decided to create a CAN Bus so you don’t have as many wires,” said Miller. “They also moved to wireless communication such as wireless tire pressure sensors. Now you have outside signals coming into the car, and those signals have vulnerabilities that can lead to compromises from the outside world.”

The communication systems of cars became more complex with the addition of steering and braking features. “They added non-collision safety features, and that gets you close to the brakes. Parallel parking technology means a computer can control your steering, and it’s all connected together,” said Miller. “That means there is a computer attached to your brakes and steering. Once you get in, you can talk to other areas of the car.”

Miller and Valasek then moved on to Miller’s Jeep. “We were able to hack into the Jeep. We found we didn’t need to be near the car,” said Miller. “We told Chrysler we could do it and they ignored us. When Wired published the article about our hacking, they fixed the problem in like two weeks.”

To enter the Jeep, Miller and Valasek needed to dig into the chips at the center of the vehicle’s information system. “We found there were two chips in the CAN Bus, and there was a connection between the chips. I could reach the one that controls the car, but I couldn’t control the chip,” said Miller. “But we discovered that the other chip could reprogram the chip that controls the car. Once we learned that, we could go anywhere.”

Through the process of learning how to manipulate the chips, Miller and Valasek kept goofing up the chips. They had to keep getting the chip repaired at the Jeep dealer. “Reprogramming the chip was really bad. I kept having to go back to the dealer to get the chip fixed -- on warrantee. I kept saying, ‘This must be a lemon,’” said Miller.

Getting into the chips allowed the hackers to begin to manipulate the Jeep, but it took more time to learn how to grab complete control of the vehicle. “We could get the brakes to not work, but only if the car was moving very slowly. The system prevented us from cutting out the brakes if the vehicle was going fast,” said Miller. “We found ways to bypass that and crash the Jeep. We didn’t really want to crash it, but it was kinda cool when it happened.”

Car Hackability Is Just Beginning

Miller noted that cars continue to have a number of vulnerabilities that challenge the auto industry. “There are now 40 or 50 computers on your car, all talking to each other. There is one central computer, and it’s not made by the car company,” said Miller. “My car has WiFi. I found a vulnerability in how it processes information from the outside world. I figured it would take months to exploit the car, but it only took about five minutes. There was an interface that faced the outside world. And that’s a feature not a bug.”

As new features show up on cars, new vulnerabilities will appear. “Cars actually have web browsers now. BMWs have web browsers,” said Miller. “Can we all agree you can’t make a web browser secure?”

After all his experience, Miller concludes that the vulnerabilities are inherent in a car’s connectivity. “The lesson is that cars were always insecure but it didn’t matter because they weren’t connected. That has changed,” he said. “We don’t want to wait until cars can get hacked and crash, so we’re trying to get car makers to become aware of the problem.”

Rob Spiegel has covered automation and control for 15 years, 12 of them for Design News. Other topics he has covered include supply chain technology, alternative energy, and cyber security. For 10 years he was owner and publisher of the food magazine Chile Pepper.

The Story Behind Hacking the Jeep

The Story Behind Hacking the Jeep

When Wired ran the story about Charlie Miller and Chris Valasek hacking a Jeep and running it off the road last year, it was not some snappy lark. The process took several months of painstaking effort to learn the vehicle's information system and crack the code. In the end, the two scientists (Miller has a PhD in mathematics and Valasek has a degree in computer science) figured out they had to enter the Jeep's CAN Bus brains to reach the steering and the brakes.

At a keynote talk at the ARM TechCon conference this week, Miller offered the details of the hacking and warned that vehicles will not be cyber-safe anytime soon. He started off explaining that car hacking is very recent, since hackers didn't realize cars were vulnerable until just the last few years. "Hacking cars started in 2010. Until then, people didn't realize there are computers in their cars. They didn't realize that if you plug into a car, you can cut the brake lines," said Miller, who works as an engineer at Uber. "I read the papers about the first hackings and decided this was something I wanted to do."

Miller noted that the first car hackers entered through OnStar. "OnStar is a service that allows you to call for help. They dialed into OnStar and took over the car," he said. "They did it in a testing track. They could lock up individual brakes, and they were able to stop the car. They didn't release any details, so I didn't have anything to go on. They didn't even reveal what type of car they used."

For their first hacking, Miller and Valasek used a Ford Escape and a Toyota Prius. "We went to a car dealer and bought the cars. We hacked in and found we could control the keys and the locks," said Miller. "We were able to control the steering. It was inconsistent, but we could do it sometimes. It would take 30 minutes."

The Vulnerabilities Are in the Features

Through the process of hacking, Miller and Valasek learned how the data systems in cars are put together. They discovered the importance of the CAN Bus. "Cars have changed. As you add more and more features, you have all this wire in the car. That's weight and cost, so car companies decided to create a CAN Bus so you don't have as many wires," said Miller. "They also moved to wireless communication such as wireless tire pressure sensors. Now you have outside signals coming into the car, and those signals have vulnerabilities that can lead to compromises from the outside world."

The communication systems of cars became more complex with the addition of steering and braking features. "They added non-collision safety features, and that gets you close to the brakes. Parallel parking technology means a computer can control your steering, and it's all connected together," said Miller. "That means there is a computer attached to your brakes and steering. Once you get in, you can talk to other areas of the car."

Miller and Valasek then moved on to Miller's Jeep. "We were able to hack into the Jeep. We found we didn't need to be near the car," said Miller. "We told Chrysler we could do it and they ignored us. When Wired published the article about our hacking, they fixed the problem in like two weeks."

To enter the Jeep, Miller and Valasek needed to dig into the chips at the center of the vehicle's information system. "We found there were two chips in the CAN Bus, and there was a connection between the chips. I could reach the one that controls the car, but I couldn't control the chip," said Miller. "But we discovered that the other chip could reprogram the chip that controls the car. Once we learned that, we could go anywhere."

Through the process of learning how to manipulate the chips, Miller and Valasek kept goofing up the chips. They had to keep getting the chip repaired at the Jeep dealer. "Reprogramming the chip was really bad. I kept having to go back to the dealer to get the chip fixed -- on warrantee. I kept saying, 'This must be a lemon,'" said Miller.

Getting into the chips allowed the hackers to begin to manipulate the Jeep, but it took more time to learn how to grab complete control of the vehicle. "We could get the brakes to not work, but only if the car was moving very slowly. The system prevented us from cutting out the brakes if the vehicle was going fast," said Miller. "We found ways to bypass that and crash the Jeep. We didn't really want to crash it, but it was kinda cool when it happened."

Car Hackability Is Just Beginning

Miller noted that cars continue to have a number of vulnerabilities that challenge the auto industry. "There are now 40 or 50 computers on your car, all talking to each other. There is one central computer, and it's not made by the car company," said Miller. "My car has WiFi. I found a vulnerability in how it processes information from the outside world. I figured it would take months to exploit the car, but it only took about five minutes. There was an interface that faced the outside world. And that's a feature not a bug."

As new features show up on cars, new vulnerabilities will appear. "Cars actually have web browsers now. BMWs have web browsers," said Miller. "Can we all agree you can't make a web browser secure?"

After all his experience, Miller concludes that the vulnerabilities are inherent in a car's connectivity. "The lesson is that cars were always insecure but it didn't matter because they weren't connected. That has changed," he said. "We don't want to wait until cars can get hacked and crash, so we're trying to get car makers to become aware of the problem."

Rob Spiegel has covered automation and control for 15 years, 12 of them for Design News. Other topics he has covered include supply chain technology, alternative energy, and cyber security. For 10 years he was owner and publisher of the food magazine Chile Pepper.