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  1. CDRIVE

    Heating Element?

    Talk about slow! I stared at this for five minutes. Finally got it! Chris
  2. CDRIVE

    Feedback on creating circuit boards

    Deserves a Sticky or placed in the Awards thread. oyvdahl, I want to commend you for not only the content of your website but also its structure and layout. You did a fine job there. After I post this I'm emailing my geek circle with a link to this thread. Chris
  3. CDRIVE

    Heating Element?

    Maybe Donkey. As for me? Nope not a clue! Should I have? Chris
  4. CDRIVE

    diode for collapsing magnetic field

    I explained that in my first reply, in the Edit comment. But my primary concern is what's destroying his relay contacts. Windshield wiper motors and power windows can approach 10A and I don't think flyback diodes are employed. You can bet his tractor starter motor draws More than this 20A motor...
  5. CDRIVE

    diode for collapsing magnetic field

    I realize that. Chris
  6. CDRIVE

    Heating Element?

    I think you would be far better off using (PWM) Pulse Width Modulation.. Chris
  7. CDRIVE

    diode for collapsing magnetic field

    While I won't discount that BEMF is causing the failure I'm skeptical because a starter motor can pull > 300A and I know of no diode used with them to protect the solenoid contacts. What does the control circuit look like? I'm talking about the relay control voltage. Is it a simple air...
  8. CDRIVE

    diode for collapsing magnetic field

    Bob, that's what I'm questioning. A DC motor isn't a simple inductor. If the source is removed while the armature is rotating I would expect it to operate as a generator with the polarity identical to the original source. One of the most basic DC motor experiments involved driving the motor from...
  9. CDRIVE

    Trouble with diffrential amplifier output

    Try wiring it like this. I get 50mV at TP3. To obtain absolute zero I think you will need to use bipolarity supplies though. Chris
  10. CDRIVE

    diode for collapsing magnetic field

    I don't want to confuse the OP any more than he already is but after reading the replies since I posted this quote I can't help but reiterate it. Chris
  11. CDRIVE

    diode for collapsing magnetic field

    Yes, like that. ;) Chris
  12. CDRIVE

    diode for collapsing magnetic field

    I don't know what you mean. What other place, other than across the relay contacts? Chris
  13. CDRIVE

    telephony question

    Have you measured the PSU voltages? Did you measure the loop voltage,.. on and off hook? Chris
  14. CDRIVE

    diode for collapsing magnetic field

    If relay contact destruction is the issue, then short of insuring that the relay is sufficiently sized, I would think a snubber would be more appropriate. Unless I'm mistaken and unlike a common inductor, I would expect the free wheeling EMF developed by a brush DC motor to be the same polarity...
  15. CDRIVE

    Trouble with diffrential amplifier output

    Is the OpAmp Vcc 24V or 2.4V? Chris
  16. CDRIVE

    Simple 555 synth idea

    I don't think you understand. RL is not part of the filter. RL represents the load that the filter sources. RL is representative of the input impedance of the next stage that the filter supplies signal to. The source impedance isn't part of the filter either. It represents the output Z of a...
  17. CDRIVE

    regarding capacitors as shorts for ac

    I use a fairly elementary approach. Once I calculate the base input Z of BJT amp I'll select a coupling cap with Xc at least 10 times less than the base Z at the lowest input freq. Chris
  18. CDRIVE

    Simple 555 synth idea

    I just thought I'd post this to follow up on your questions regarding LC filters. Shown is a low pass filter with a -6dB knee @ 17KHz. The source impedance of VG is 600Ω and RL = 600Ω. As far as resonance is concerned, this is a low Q circuit so the curve looks virtually flat until cut off freq...
  19. CDRIVE

    Need help with some basic electronics, please.

    Are you sure that your cam pulls 2A? That's a lot of juice! Chris
  20. CDRIVE

    video over cat5 without baluns

    At 75 feet, ..150 feet round trip, I really don't see an issue with CAT5. Even if it is a problem you have two more free pairs you can parallel up. Chris
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