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  1. CDRIVE

    led coil generator problems

    I forgot to mention that Schottky Diodes are best for this application because they have a very low forward voltage drop.
  2. CDRIVE

    led coil generator problems

    Your plastic pen isn't going to provide much flux density and you'd be far better of charging a large cap by rectifying the AC. When it's charged use a switch to turn on the Led. The cap will have far more current capacity than your coil will.
  3. CDRIVE

    Switch for oscillator (and some book recommendations too)

    Three pin phone plugs/connectors are stereo. They can be used for mono too. In fact, if mono is all that's needed, a stereo phone plug can be plugged into a mono jack but a mono phone plug should not be plugged into a stereo jack. Have I confused you yet? :confused::D I think I just confused...
  4. CDRIVE

    Digital Pot setup

    Nice find. It has the de-bounce circuitry built in. Question though.. Unless I calculated this wrong, to sweep the pot from 0 to Max you will have to hold the Up button down for 8.6 seconds. Is this acceptable to you? If not I have some thoughts on a work around using a 556 to semi-automate...
  5. CDRIVE

    Filters

    This is governed by the 'Q' factor of resonant circuit. The higher the Q the greater the resonant voltage developed across a tank will be. Q effects both parallel and series resonance. There are circuits known as "Q multipliers". Google it. BTW, whole hard cover text books have been written on...
  6. CDRIVE

    Switch for oscillator (and some book recommendations too)

    Take a look at these. http://www.mpja.com/1_8-1_4-Phono-Connectors/products/335/
  7. CDRIVE

    Digital Pot setup

    Justin, before we veer off into a particular direction could you please describe where the Up/Down speed buttons are going to be? If they're inside the water tight case how do you access them? If they're not, how are you going to protect them from the water and how are you going to get the...
  8. CDRIVE

    Switch for oscillator (and some book recommendations too)

    Yes and Yes.
  9. CDRIVE

    Digital Pot setup

    This is going to be easier to do and provide more options if we can facilitate low side switching. Please post your schematic so we can see if low side switching is applicable.
  10. CDRIVE

    Switch for oscillator (and some book recommendations too)

    You can also use a 'Single Pole - Double Throw - Center Off' (SPDTCO) toggle switch. They're easer to find than a rotary switch. Cheaper too! ;)
  11. CDRIVE

    Question about RF coil

    More than likely no. Unfortunately, the P-C70-RF link doesn't list the inductance of the primary and secondary windings. The P-C70-RF is a classic design that brought a smile to my face when I saw it. At one time, it was quite common..... Ah, memories. :) Also, I don't know what the author...
  12. CDRIVE

    Basic transistor Guitar Amp

    Bob, my original comment was in response to this statement and as for the Vcc not being 9V.. what's this? https://www.electronicspoint.com/attachments/4381d1337213150-basic-transistor-guitar-amp-audioamp.jpg My concept of what constitutes a guitar amplifier is obviously far different from...
  13. CDRIVE

    Led transistor driver circuit help!!!

    I re-read your first post and it leads me to believe that your LEDs are made up of those commercially made LED strips? If they are, they're made up of a series-parallel circuit. The series portion consists of 3 series LEDs and a limiting resistor. The parallel section repeats this to the end...
  14. CDRIVE

    Basic transistor Guitar Amp

    Hello Bob. My calculations indicate that when RL is dissipating 1W then RS is dissipating 2.18W. Chris.
  15. CDRIVE

    Basic transistor Guitar Amp

    Bob, with all due respect, you may want to recalculate.
  16. CDRIVE

    Basic transistor Guitar Amp

    You're right it isn't the same. It's more. Your logic only holds true for Class D switching. Do the math on this simple representation of a 9VDC source feeding an 8 Ohm load. Assume 500mW for RL power dissipation. Then calculate what value RS must be to deliver 500mW to RL. Finally, calculate...
  17. CDRIVE

    Basic transistor Guitar Amp

    Yes, I've used the 2N2222 to drive speakers =>30 Ohm operated class D but the application was mainly for producing an alert tone, where distortion wasn't a factor. I don't see them as a good choice to drive 8 or 4 Ohm speakers., where faithful signal reproduction is vital. The 2N2222 is...
  18. CDRIVE

    Basic transistor Guitar Amp

    Here's a stereo power amplifier chip. You only need to use one half of it. I'm certain there are a host of mono chips available too. On the other hand, if this is something that you want to build with mostly discrete components please post so...
  19. CDRIVE

    Basic transistor Guitar Amp

    What kind of speaker are you going to be driving? The 2N2222 is used in applications as a small signal or switch. It's not intended as a power amplifier. Power transistors are most commonly found in TO3 or TO220 case styles and are much larger than a 2N2222 to facilitate dissipation of heat.
  20. CDRIVE

    Led transistor driver circuit help!!!

    I must have misinterpreted the data sheet on the 4066. I was under the impression that it was an open drain switch. Guess not. Thanks for correcting me... and yes, it would invert the logic.
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