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Case #86: Bill Had That Weird Sensation He Was Being Watched
By Design News Staff -- Design News, June 25, 2006
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.
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For Bill Bowden's complete instructions to build your own Fading Red Eyes circuit, go to
| "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 µF Capacitor | 852-6516 |
| 1 | Solderless Breadboard | 237-0015 |
| 2 | Red LED | 670-1224 |
| Additional parts required: 9V Battery | ||
Talkback
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HELP. The LEDs are on but aren't...
- 2006-21-10 08:06:49 EDT -
PDF instructions are not available at link. Does anyone have this info?...
- 2006-13-10 09:09:06 EDT
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