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  1. Herschel Peeler

    Can anybody explain about how bjt works??

    As you pull current through the emitter - base the resistance between the emitter and collector changes. Gain = collector current divided by base current.
  2. Herschel Peeler

    Transformer Help

    Now that you have a good idea of voltages look at similar transformers of that type and size for an idea of currents.
  3. Herschel Peeler

    Components Buyers Guide [for Dummies]

    Shottky Diodes - maximum voltage and current, surface mount or leaded. heck out some data sheets on popular parts. 1N6263. 1N5718. Regular Silicone Diodes - maximum voltage and current, surface mount or leaded. 1N4148, 1N4004 Transformers - voltage and current. Get a distributor's catalog...
  4. Herschel Peeler

    Circuit Design

    Power supplies are a good place to start. Then add a voltage regulator. Then current limiting.
  5. Herschel Peeler

    Heatsink

    How much heat are you trying to dissipate? Fan or no fan?
  6. Herschel Peeler

    Help with diode OR gate

    You don't need the resistor. You are not doing logic. Just diodes. I suggest a Schottky for less loss.
  7. Herschel Peeler

    Need help IDing parts

    Not much of a market for leaded parts these days except to schools and hobbyists. Donate them to a school with an electronics program if you can find one and take the tax write off.
  8. Herschel Peeler

    74HC oscillator, how fast?

    Reliably, maybe 3 to 5 MHz. Selecting parts you might get 50 MHz. At what voltage is another question.
  9. Herschel Peeler

    Just need a few suggestions

    35 year old GPS system? Yes, 35 year old battery is a question. Lights, speaker ... no big problem. Vibrator might be better than speaker. Small receiver, no problem. Sounds like the basis for a good story.
  10. Herschel Peeler

    Component Storage

    Resistors I keep in a 2" x 3" plastic bags and in a 3 qt plastic "shoe box". The she box fits nicely in a file cabinet drawer. Pots, diodes, capacitors and such I keep in plastic bins. They also fit nicely on file cabinet drawers. ICs and unique small stuff I keep in drawers. (lots of drawers.)...
  11. Herschel Peeler

    Led Flashlight Help

    More info on your DC to DC converter, please. 12 V in, 4 V out means you waste 8 V in heat?
  12. Herschel Peeler

    Zener Diode

    The Zener diode will regulate the voltage across the resistor, just as it is suppose to do.
  13. Herschel Peeler

    Remote Stay Or Go Light

    Electronic Goldmine has used traffic lights. About 12" in diameter. I think they run on 120 V AC. Cost about $8.00 last time I looked.
  14. Herschel Peeler

    Electric Toothbrush

    Not necessarily an electrical problem. Maybe a buildup of toothpaste in the mechanism. Take it apart and clean it. Maybe a bad switch.
  15. Herschel Peeler

    Clapper Light Control Circuit Problem.

    Your basic circuit is good. My version of it works. There are some differences. My mike was a 3-wire electret type so I had a wire to power you might not need. The mike output was really low so I had to push the gain up to about 150. I powered it from 5 V and used a 74LS74. Instead of a relay I...
  16. Herschel Peeler

    Clapper Light Control Circuit Problem.

    TTL running at 16 V?
  17. Herschel Peeler

    Product identification request

    I can't tell size. Does it look like it could fit over your finger? Blood pressure monitor?
  18. Herschel Peeler

    Memory Addressing

    Does the memory have to be at ant certain address? Lower address lines go to the memory's address lines. Higher address lines get decoded to select the memories. Program memory starts at address 0? 386 interrupt vectors start at 0? Yes, 386 may have 32 address lines but memory management can...
  19. Herschel Peeler

    Electronic torch, Battery won't get charged.

    Ah, the LED will last 50,000 hours ... but not the electronics that charge the battery. Repairs are difficult. Toss it and buy a simpler torch ...just batteries and LED, no electronics.
  20. Herschel Peeler

    Resistor on illuminated switch but without dimming the circuit LEDs??

    It doesn't give a resistor value. I think we can assume there's not one. How much brightness do you want? Dim, 5 mA, 2,000 ohms at 12 V Full, 20 mA, 510 ohms In between, 10 mA, 1,000 ohms
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