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  1. Tha fios agaibh

    What's wrong with circuit?

    Ahh ha. It was an interference after all, as I believe Colin was hinting to. I took the circuit home from work and all the little gremlins went away. It works, but it's a bit too sensitive even with replacing the 220k bias resistor with a 180k. I think I need to add more filtering to the high...
  2. Tha fios agaibh

    What's wrong with circuit?

    Why? Do you suspected I'm picking up interference and the isolation Xformer will filter it out? (alas, I don't have one) As I said, the triac is always on at this point. Why would I want to short from base to emitter? Conversely It may be worth trying to short collector to emitter and see...
  3. Tha fios agaibh

    What's wrong with circuit?

    I get you point but I'd hardly call Fluke an inferior brand. No, there's no high frequency applied because the Tx circuit is not turned on. So I don't think there's over 60hz on this circuit or perhaps a harmonic of it. I can show the Tx circuit but I believe it works fine as I can hear the...
  4. Tha fios agaibh

    What's wrong with circuit?

    Well, that's what my fluke meter tells me. What I'm trying to figure out is why my triac is staying on. It's only supposed be on when the high frequency from Tx is applied. I believe it's because the base is not negative enough to drive the transistor into full saturation. Do you agree?
  5. Tha fios agaibh

    What's wrong with circuit?

    On second thought, the 9ma must not be coming from the cap. If we know there's 3v dropped across the 330R then we know the 9ma is flowing through it, and the gate current of the triac is probably that much. Right?
  6. Tha fios agaibh

    Happy New Year!

    ....And a hexy New Year to you too.
  7. Tha fios agaibh

    What's wrong with circuit?

    Yes, must be. (embarrassed I didn't notice the obvious) I thought it was coming from collector side. I'm trying to figure why triac is always on. Do you agree that this is a biasing problem? I believe the 220k resistor and pot should be low enough resistance to drive the base negative to fully...
  8. Tha fios agaibh

    What's wrong with circuit?

    My guess is the 220k biasing resistor needs to be lowered in order to fully saturate transistor that in turn would turn fully short gate voltage?
  9. Tha fios agaibh

    What's wrong with circuit?

    I'm not sure what reference point I should be using here, but from bottom of 1k resistor below collector, I'm using as negative. Voltage on base and emitter are the same and I'm not sure why. Transistor should not be forward biased unless base is more negative than emitter, so why am I passing...
  10. Tha fios agaibh

    What's wrong with circuit?

    Better?
  11. Tha fios agaibh

    What's wrong with circuit?

    Thanks, I've never heard of that rule of thumb. Very cool. Now I can't understand why triac is always on. Gate voltage is 0.81 to .83 depending on pot position. Turning on transmitter makes it jump slightly (0.02v) but something is wrong. Checked transistor and diodes and all are working...
  12. Tha fios agaibh

    What's wrong with circuit?

    May I ask how you got 24ma? I was expecting an impedance of 4k across the 220R, 220K and paralleled .68 cap. giving me 45ma. Oh, I was figuring the transistor was only switched on when high pass filter (caps on the left) allowed enough current to pass to the base and only then switching on...
  13. Tha fios agaibh

    What's wrong with circuit?

    Thanks for explanation. Oops, I found a solder point I missed between those two diodes. Now, I have 17v at top of 1k and 5.3v at collector. That's more like it! I'll fiddle with it tomorrow and see if it works. Thanks so much for your help.
  14. Tha fios agaibh

    What's wrong with circuit?

    better?
  15. Tha fios agaibh

    What's wrong with circuit?

    Thank you Colin, but can you elaborate? 1,000v? I'm applying 120v and was expecting voltage in the single digits above transistor. I should either be forward biasing the transistor and sending enough voltage to trigger the gate, or have a large Vce reading otherwise, right? Vce is only 0.5v...
  16. Tha fios agaibh

    What's wrong with circuit?

    I got this video link from bluejet for a remote control power circuit, but I wasn't able to get it working. It was originally posted under projects, but I'm reposting here because I could really use some circuit help here. Here's a sketch of receiving circuit using values given in video...
  17. Tha fios agaibh

    Remote sensor on powerline

    From top of 1k resistor to bottom rail I only get 1.25v. Vce is only 0.5v I need at least 1.5v to turn on the triac, right?
  18. Tha fios agaibh

    Remote sensor on powerline

  19. Tha fios agaibh

    Remote sensor on powerline

    Thank you Bluejets for that circuit but I couldn't get it to work. I believe my transmitter portion is working ok because I can hear the high frequency when I apply 12vdc. The receiver portion doesn't seem let enough voltage through for it to work. I believe I followed parts list and circuit...
  20. Tha fios agaibh

    14.8v @ 16 amps down to 12v @ 8 amps

    True, but notice I didn't say rated voltage. Having the actual camera and ps specs would be useful here.
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