DN Staff

June 26, 2006

2 Min Read
Case #86: Bill Had That Weird Sensation He Was Being Watched

Partial to things that go bump in the night, Bill built a circuit that slowly illuminates and fades a pair of red LEDs. It consists of two op amps, one producing a slow rising and falling voltage (3 - 6V) and the other functioning as a voltage comparator. In operation, a linear 3V ramping waveform is generated at pin 1 of the LM1458 IC and buffered with an emitter follower transistor stage. Make the rate adjustable by using a 100K potentiometer in place of the 47K resistor at pin 2. Install it in a skull as a Halloween prop or if spooky things aren't your thing, use it as a fancy power indicator for a home appliance.

For Bill Bowden's complete instructions to build your own Fading Red Eyes circuit, go to

click here

"Fading Red Eyes" Parts List

Amt

Part Description

Allied Part #

2

Operational Amplifier LM1458

288-1090

4

4K Resistor

296-2182

1

100K Resistor

296-5610

1

100 ohms Resisistor

895-0465

1

Transistor 2N3904

568-8253

1

22 muF Capacitor

852-6516

1

Solderless Breadboard

237-0015

2

Red LED

670-1224

Additional parts required: 9V Battery

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