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  1. CDRIVE

    Amplitude Modulation using Op Amp.

    Miguel, nothing wrong with doing a Fourier Analysis but here's a simpler demo of what I call pseudo AM, using the wavefrom you described. Look what happens when the modulated signal is coupled through a 1000pF cap. As you can clearly see there's no perceptible audio energy coupled to RL. If you...
  2. CDRIVE

    Valve (tube) amplifier schematic help

    Love the attitude. You're going to work out well here. :D Welcome! Chris
  3. CDRIVE

    Amplitude Modulation using Op Amp.

    Perhaps, because it's not really AM. ;)
  4. CDRIVE

    Valve (tube) amplifier schematic help

    There's no reason to abandon the original design. It just needs to be modified for use with a low impedance load. Speaking of which.... We discussed the that the 12AU7 amp was intended to drive a high Z input guitar amp. This discussion was quite extensive early in the thread. You never...
  5. CDRIVE

    Valve (tube) amplifier schematic help

    Take a look at what happens to the output signal when the load (RL) is 100KΩ (FigA) and when it's reduced to 36Ω (FigB) Chris
  6. CDRIVE

    Valve (tube) amplifier schematic help

    I'll post it then. Chris
  7. CDRIVE

    Valve (tube) amplifier schematic help

    Not surprising. Many earphones today are actually small speakers. Waaaaaaaaaaaaaaay too low Z for your preamp. I'll post an example of what impedance means to you and why it's important.. Chris On second thought I don't want to do this unless you understand Ohms Law. Do you?
  8. CDRIVE

    Valve (tube) amplifier schematic help

    We covered this early in the thread. I thought you understood it. This amplifier is designed to drive a PA with an input Z >=100K Ohms. It's not designed to drive low Z earphones. It will drive a crystal earphone though but they don't have good low freq response. Just for the hell of it...
  9. CDRIVE

    Electronics construction with a musical twist

    That's clever stuff! I don't know if it's still popular these days but at one time electronics art was very popular. It was found on office walls and reception areas of electronics firms in the 60's - 70's. I remember a large bald eagle that looked 3D at a distance. When up close you could...
  10. CDRIVE

    which power converter to buy?

    Are you sure that you don't have a missing decimal point? Inrush current<=30A. That's 720W @ 24V! What is the "Screen Device"?
  11. CDRIVE

    Valve (tube) amplifier schematic help

    You need to post much more information so we can diagnose your problems. I hope your not using that protoboard with long jumpers to the tube. Also. many protoboards don't have any insulation on the bottom side. They shouldn't be sitting on a metal object. Multiple nodes could short out...
  12. CDRIVE

    Amplitude Modulation using Op Amp.

    Miguel, what power output to you want this transmitter to have? Chris
  13. CDRIVE

    Valve (tube) amplifier schematic help

    I'm happy with your excitement and desire to dive in. No problem with PMs but I'll ask you to include the link to your new topic. This is because EP is an educational forum, PMs benefit only the recipient and deprive other members that might be interested in your topic. Someday another nube...
  14. CDRIVE

    Amplitude Modulation using Op Amp.

    Thanks Steve. It was a rhetorical question. Quote (Judge Judy): "I was born at night but not last night"! Chris
  15. CDRIVE

    Light Photo-sensor Timer Help Please!

    It doesn't take a psychic to know this is a class assignment. No one will be doing either of you a service if they do any more than guide you guys. Chris
  16. CDRIVE

    Amplitude Modulation using Op Amp.

    Please rephrase your statement, as I'm not sure what you're trying to convey in the large print.
  17. CDRIVE

    No juice through bridge rectifier

    These things usually have a large cap too!
  18. CDRIVE

    Rectifier circuit fails when capped.

    Electro caps can be +- 20%, have variant leakage and ESR. It's good practice. Chris
  19. CDRIVE

    Rectifier circuit fails when capped.

    Please stop with the photos and post a schematic. Draw it if you have too.
  20. CDRIVE

    Amplitude Modulation using Op Amp.

    Please post the FET & OpAmp part numbers. Chris
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