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  1. AnalogKid

    "random" blinking LEDs: purpose-built circuit, or Arduino or =

    None of those schematics have current limiting resistors for the LEDs. Look into joule thief circuits. If you can get the flash circuit small enough, you could have one at each LED rather than a central controller. Then, the only thing connecting the LEDs is power and ground, so you can...
  2. AnalogKid

    Help on aquarium project

    Best to wait until you have a viable schematic. I'll work on one later today. ak
  3. AnalogKid

    heat emitted by LED signs and lights.

    Are you asking about the heat produced by the entire display system (power supply, control electronics, drivers, LEDs) or just the LED emitters themselves? ak
  4. AnalogKid

    Simple digital clock

    1 M is a very high input impedance. It would take very little radiated energy to impress a couple of volts across it, enough to cause the gate to change state. ak
  5. AnalogKid

    Simple digital clock

    Or 100K. In theory, even 1M will work, but that might leave the gate inputs susceptible to noise. ak
  6. AnalogKid

    Help on aquarium project

    A simple light sensor circuit is, well, simple. It doesn't know the difference between faint morning light and faint evening light. With one sensor and two comparators, a full cycle would go like this: night - blue morning - blue + white day - off evening - blue + white...
  7. AnalogKid

    What cap, what resistor?

    I can state with perfect authority: Yes, the capacitor is too big. ak
  8. AnalogKid

    555 Timer IC monostable

    And a photo. We're not telepathic, either. ak
  9. AnalogKid

    Help on aquarium project

    What is the output current rating on the power supply. This gives a clue to the kind of switch part to use. ak
  10. AnalogKid

    Help on aquarium project

    It looks like a 3-position switch. Yes? It looks like the 12 V source plugs into the bottom of the switch/mounting module. Yes? If yes, yes, then there are a couple of ways to approach this. With the circuit mounted on the back (top side) of the light assembly, wires can run down the...
  11. AnalogKid

    Help on aquarium project

    A light sensor circuit with two outputs and a little logic is not difficult. Making it work in your application needs more information. Where is the switch located with respect to the lights and the 12 V power supply? Is the supply 12 V DC? Does the switch go to a dimming controller? If this...
  12. AnalogKid

    Can you names the parts???

    Yeah, I mentioned that in post #3. But going back to the 60's, I've seen a K on the end of some pretty low quality caps, usually small ceramics in RF circuits. Has the K=10% code been around that long? ak
  13. AnalogKid

    Can you names the parts???

    Here is an image of a verified 0.1 uF film capacitor. 104 is the standard European code for the value. For reasons I've never known, the K stands for picofarads, so the translation is 100,000 pF. This is why my second guess for your second cap is 68 pF, although there is a possibility of 680...
  14. AnalogKid

    to hire someone who knows s/w turn ckt-diag into PCB Gerber fabrication files

    Are you reverse-engineering something? Are the <whatever> files used to create the first pc board available? ak
  15. AnalogKid

    Help With a LED Clock Kit Please

    The display pinouts in posts 4 and 5 are not the same. ak
  16. AnalogKid

    Can you names the parts???

    https://en.wikipedia.org/wiki/Tantalum_capacitor ak
  17. AnalogKid

    Help With a LED Clock Kit Please

    Please post something: the schematic, a link to the assembly manual, whatever. ak
  18. AnalogKid

    Can you names the parts???

    The first one is a dipped tantalum electrolytic capacitor. It should have a small + sign near one lead. What are the other markings? The second could be 0.68 uF, non-electrolytic, maybe stacked ceramic or stacked metal foil. Or, 68 pF +/-10%. ak
  19. AnalogKid

    Need help with this certain circuit (RC phase shift system)

    The pot in post #1 does not do anything because it is shorted out. The pot in post #5 will vary the volume or loudness, but will not change the frequency of the tone. An LM386 will *barely* operate on a 5 V supply. Read the datasheet to see the normal operating voltage range. To your original...
  20. AnalogKid

    Morse buzzer

    Agree. I recommend a 1-transistor phase-shift oscillator at a lower freq like 200-400 Hz. ak
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