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  1. AnalogKid

    Vbe of 2n3904 in led driver circuit

    LOVE the 2596 module. Great find! ak
  2. AnalogKid

    Trigger Pulse for IC555 using Inverted Square Pulse

    Yes. The first RC is the variable delay. Think 2-row header with programming shunts to adjust the delay period. No shunts equals no delay (0 ms). The second RC is the fixed width output pulse. The more I read the TS requirements, the less clear they were, so I just threw out a guess. It...
  3. AnalogKid

    Trigger Pulse for IC555 using Inverted Square Pulse

    It would help to see the MOSFETs and their load to get a complete picture. But from what you describe, it sounds like you want FET-A to turn on during every 12 V pulse out of the sensor, and FET-B to turn on at the end of the FET-A on-time, for a variable length of time. 1. By 0 ms do you...
  4. AnalogKid

    Resistor help

    If you need a more stable and repeatable source, Digi-Key, Mouser, Avnet, TTI, Newark, etc. ak
  5. AnalogKid

    Question about current sources - Not getting the correct current through load

    Thanks. Some of the posts now make more sense. ak
  6. AnalogKid

    Question about current sources - Not getting the correct current through load

    My point was that there are many on this forum who do not have the referenced book, so this whole thread has the feel of an in-group/out-group dialog. I don't think it is too much to expect that anyone asking or describing anything on an electronics forum should pitch in a schematic. It is a...
  7. AnalogKid

    Question about current sources - Not getting the correct current through load

    What is obvious is ten posts and no schematic. ak
  8. AnalogKid

    Vbe of 2n3904 in led driver circuit

    Actually, his request was clear, concise, included both context and a schematic, and asked a specific question about a specific issue. I didn't see your schematic. ak
  9. AnalogKid

    Vbe of 2n3904 in led driver circuit

    Vbe increases with base current, decreases with temperature, and increases with collector current. Also, it varies from one part to another. Whatever the textbook says is the correct value for a small signal transistor, know that these things *always* come with a range of values. Figure out...
  10. AnalogKid

    Converting a Sync on Green signal to VGA/HDMI or anything 720p+ capable

    ARCNET - ? Really?!? Always liked ARCNET, unpretentious little LAN. ak
  11. AnalogKid

    Inject sound to a phone landline

    If you were injecting directly into the phone line that would be true, but the circuit already shown would work for that. But the high line voltage does not appear at the handset jack, so the only requirements are low DC voltage isolation and adjusting the audio level to match what the phone...
  12. AnalogKid

    How to toggle on/off via Power Line?

    Everything you describe can be done with X-10 modules. ak
  13. AnalogKid

    Where to get a 4017 chip

    Digi-Key, Mouser, All Electronics
  14. AnalogKid

    Inject sound to a phone landline

    What is the "iso ampli"? If this is an opamp, a small audio amplifier with speaker outputs, an MP3 player, or what? Whatever it is, we can figure out how to couple it to the handset jack on the phone. All of your drawings show a connection to the micropphone in the handset, but this will not...
  15. AnalogKid

    Flip-Flop Circuit Using BJT's, OP Amps, and Cap Timer

    A ff and an osc do not perform essentially the same function. One is designed specifically NOT to oscillate on its own, and the other is an oscillator. While a 2-transistor multivibrator and a 2-transistor flipflop look similar in a schematic, the nature of the cross-coupling is completely...
  16. AnalogKid

    Flip-Flop Circuit Using BJT's, OP Amps, and Cap Timer

    First, are you trying to make a flipflop or an oscillator? These are not the same thing. Second, 3 M is way too large a resistor for base current limiting. You don't say what any of your components are, but with a normal opamp you're looking at less than 2 uA base current. Third, the 555 is...
  17. AnalogKid

    I have an in-car camera that requires signal from an electret microphone.

    The nominal signal for normal speech varies depending on the sensitivity of the electret element. A starting point for a design is about 5 mV rms. Can you confirm that the 2.5 mm input is mic or line level?
  18. AnalogKid

    sample and hold pulse source?

    http://www.geofex.com/article_folders/potsecrets/potscret.htm
  19. AnalogKid

    Use a PIR Sensor to detect a movement of a paper

    Thinking about office-sized printers, an opto-interrupter in the exit path would be relatively easy to add. But for desktop models, thermal might be the only way to go since the pages just fall out. I think they are plenty warm enough to be seen as warmer than the catch tray. But after a few...
  20. AnalogKid

    sample and hold pulse source?

    Note that with a 4093, Vcc can be anything from 3 V to 18 V. If you use a 74HC14 (or HCT, AC, ACT, etc.) then Vcc is limited to no greater than 5.5 V. Check data sheets for the exact operating range. Also, 50 ms to 3 s is a 60:1 adjustment range. That a lot for a single-turn pot. Consider a...
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