Carol has prepared a good topic, but unfortunately the host, Alex spoke more than Carol did throughout the entire presentation. And I could not believe that Alex were eating while hosting the class.
I hope the next class Alex would conduct himself more professionally.
I agree with Ran about the issue in slide 3. The words "open" and "closed" should be switch to make sense of the bulleted items. For example, when the switch is closed the diode cannot "turn on" having 12V in the cathode and ground on the Anode. Just pointing it out so there wouldn't be any confusion.
Concerning the terms BUCK and BOOST in SMPS... The central component of the SMPS is the inductor, and, counter to its cousin, the capacitor, the inductor is basically a current-operated device. (The capacitor, on the other hand, is a voltage operated device.) In the SMPS design wherein the output voltage is less than the input voltage, the inductor must "BUCK" the incoming current to reduce the output voltage to the desired level.
In the case of an SMPS having an output voltage higher than the input voltage, the inductor (by means of the callapsing magnetic field and the resulting current at input current cessation) must "BOOST" the input voltage to the desired higher output voltage.
Missed the live session today but I caught the archived replay, It's a good brginning. I'll miss tomorrow as well but be live Wednesday, I am a job searching Electronics Engineering Techbician pursuing new technology and this looks like a good place to start.
On slide 3 in the writeup on the right side, it appears the words "swith is open" and "switch is closed" are wrong in the first two bulleted items. For example, in the case of the first bulleted item, if the "switch is open," NO ENERGY WILL FLOW from the battery.
Double Insulated: Double insulated appliances are products that have been designed in a way so as not to require a safety connection to electrical earth. Typically,it's that third prong on the power cord plug. The basic requirement is that no single failure can result in dangerous voltage becoming exposed so that it might cause an electric shock, and that this is achieved without relying on a connected-to-earth metal casing. This is usually achieved at least in part by having two layers of insulating material surrounding live parts or by using reinforced insulation.
@dgutierrez - MTTF = Mean Time To Failure. MTBF = Mean Time Before Failure. The difference between the two is primarily that the MTTF involves a system or component failure that cannot be repaired.
@Alex - My interest this week would be to learn more about the state of this technology. There seems to be a lot going on with HBLEDs and sometimes lots of them. Therefore, the power supply reqs. can be intense. Configuration of the LEDs is also important as well as the choice of LEDs. There is much to know.
I have to say I'm a little disapointed that she hawks her business and then stops answering questions, Several of which I'd love to hear the answer to.
There are lots of great applications. It's great to see the diversity of LED applications. My co-author Ron Lenk is the expert on switch mode PS. He wrote a book on Practical Design of Power Supplies by Wiley. He's also available for consulting, as am I. Please contact us at sales at reliabulb dot com.
"Is there a reason there are 3 serial LED's in slide 11? Can you use this configuration in any way you want (serial, parallel, bridge, etc), or this is the standard convention?"
Just to show higher voltage to demonstrate Boost. They are generally in series.
"n the HV9910 Demo slide you mentioned the efficiency is 85%. What efficiency are you referring to? Poewr to LED input only or optical efficincy as well?"
Pin and Pout for power supply only. BTW they can be hard to measure because of the high frequency. Only research people use optical efficiency. LED people talk about efficacy, lumens/W.
Just for curiosity -- is it possible to get a summarized chat transcript (or is that part of the web archive too?), as there are a significant amount of gold nuggets in there.
"How much would you derate an electrolytic? Eg - if you had a 50V circuit application, would you utilize a 75V cap for a consumer lighting application, or would you go up to 100V?"
If you are sure the circuit never goes above 50V (even during lightning, when LEDs are in cold environment, etc.) then 63V is fine. Spend the money on higher temperature rated components.
I assume we might get into some of the high-intensity LED chips (the size of surface mount capacitors) later this week?? THAT is one thing on MY agenda.
@luizcosta, You are welcome. Yes, their demos are pretty cool. And the lightbulbs are the mesh network, so it would be easy to add sensors to the mix to detect occupancy and set lighting accordingly. Adding RGB leds would make for even more customizability.
What about touch-detection in "Table" type applications -- does that tend to have a timed, perhaps pulse-coded output from each emitter to simplify decoding where a detector is getting signal from??
"Carol - Does the inrush handling requirements change depending on the nature of the dimmer control?"
Basically no. When triac turns on every cycle, there's a rush of current. This is slightly different than in-rush that happens only on turn on. All triacs have this problem.
@luizcosta - look at NXP's smart lighting solutions, they include an ARM processor with a wireless radio in each light to make a lighting network. Each light has an IP address.
@Carol - I'm interested in design parameters for heat sinking high brightness LEDs (SMDs) such as the current crop of automotive headlamp DRLs or "angel eyes". What materials and how to mount the LED to them?
@Carol - I'm interested in design parameters for heat sinking high brightness LEDs (SMDs) such as the current crop of automotive headlamp DRLs or "angel eyes". What materials and how to mount the LED to them?
How much would you derate an electrolytic? Eg - if you had a 50V circuit application, would you utilize a 75V cap for a consumer lighting application, or would you go up to 100V?
In the HV9910 Demo slide you mentioned the efficiency is 85%. What efficiency are you referring to? Poewr to LED input only or optical efficincy as well?
Can drivers in retrofit LED Light bulbs be designed to not be impacted by leakage in conventional "leaky" AC timers used in home lighting? Pittfalls/disadvantages?
@edeanda - google what you want to find out. at least for EMI, depends from where do you want to start to suppress it (board, outside the board, case, outside of it, cab;es, etc).
RFI becomes an issue as soon as you start doing anything exotic to control pulse-rates for whatever reason. Makes a wider-range emission-control device necessary...
Will we get into consideration of the "flash" LED used on the iPhone, for example?? People can use that as a flashlight, too. And battery power limitations stack up quickly.
@luizcosta: My workaround for missing slide numbers has been viewing the PowerPoint in Normal View instead of slide show so that the numbered slide thumbnails appear to the right with the current slide highlighted.
this might be for a machine vision application where you want very specific light output. LED's might be a good fit since these systems might be on all the time.
Persistence of vision is cool -- maybe we'll get into a sequential buffer output device to display text, etc, only while in motion (like those clock displays that you only see the time output while the display wand is "ticking" in a repetitive arc.
There is an evaluation board in digikey website pn CLA367-ND, which is not the one you show on the ppt, could you let me know why the high cost of this board?
We are interested in building LED lighting projects using AC and working with PICs to control the display. Have set up one circuit with opto and triac and seems like it will work. any white papers or web links would be appreciated.
Is there a reason there are 3 serial LED's in slide 11? Can you use this configuration in any way you want (serial, parallel, bridge, etc), or this is the standard convention?
"buck" is an archaic term coming from many many years ago with higher power radio circuits; it does have a logical source, just don't have it on the tip of my tongue.
Buck and boost modules can be purchased from many IC vendors. Buck reduces voltage, boost increases it, there are others like Buck-Boost, SEPIC that can increase or reducuce voltage...
General interest, but currently rejigging a low heat fluorescent fitting to work with an incandescent dimmer (no SMPS, just a chain of LEDs off a bridge rectifier)
MikeR Unemploed Electrical test Engineer. Interested in intensity controll techinques for LEDs, and just for what is out there. Thanks for presentations
Right now, searching for a position; typically I'm a small-company R/D project/proto/product engineer.
ALSO, for anyone else who may be having problems gettting the audio feed, try Chrome. This is the first time I've HEARD anything from your lecturer(s).
I'm assuming there might be something fresh and remind-ful communicated. And hoping later for good info on high-brightness small formfactor devices.
Hi, I do custom hardware and software, mostly in custom mobile and aerospace industries. I am a project Manager, trying to opdate andrefresh my basic knowledge.
The streaming audio player will appear on this web page when the show starts at 2pm eastern today. Note however that some companies block live audio streams. If when the show starts you don't hear any audio, try refreshing your browser.
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