Recent content by witsender

  1. witsender

    Correct voltage translator

    Yeah, Bob! Good question!
  2. witsender

    How to get 80 mV?

    Ooops! Here's the drawing I made for you
  3. witsender

    How to get 80 mV?

    Yes, Harald is doing his usual, wonderful thing here... giving good advice. I can't improve on what Harald says - he's exactly right. I can put it another way though, and sometimes that's what people need, so here goes... The general subject is called "Ohms Law", and it's so useful! You need...
  4. witsender

    Replace internal AC tranny for DC adapter?

    :) Hi Martaine Yes, it very much does matter which way the DC is connected to the circuit. A good way to make the repair might be to solder the wires from the external adapter directly to the smoothing capacitor on the PC board. The 2 legs of the 22000uF capacitor are marked with + and - signs...
  5. witsender

    Correct voltage translator

    :) Hi I believe the interface circuit should probably be a Schmidt trigger. Schmidt triggers are available as 6-to-a-pack IC's. Here's a link to a datasheet for the 74HC14A... http://www.onsemi.com/pub_link/Collateral/MC74HC14A-D.PDF. You'll still want to use some kind of voltage division or...
  6. witsender

    Salt lamps - what effect would the salt have on the light from incandescent bulb

    Hi Voltaic The visible absorption spectrum could be measured using a camera. The light recorded in photographs of the unshaded lamp and the same lamp shining through the salt block would be compared using photoshop or gimp (a freeware photoshop-like application). The comparison would be done...
  7. witsender

    Help with simple circuit

    :) Then a very big part of using these modules must be knowledge of software packages that emulate radio transmission protocols. Are these software packages pretty user-friendly? Mark
  8. witsender

    Help with simple circuit

    wow. Just wow. $2
  9. witsender

    Rest in Peace, Kris

    I want to say that Kris was a good example for the rest of us. He showed understanding and patience and I am sure he helped a lot of people. I'm sorry I won't see him on the site again. Mark (previously "poor mystic")
  10. witsender

    impedance of amplifier

    Hi Bhuvanesh :) Transistor circuits are either common base, common emitter or common collector. In the case of a common emitter circuit whose input is at the base of the transistor, the input impedance is measured between base and emitter. Output impedance for such a circuit is measured between...
  11. witsender

    Pilot light to detect break in resistive load

    Ohhh. I suppose you could use the same pulse transformer to supply little flicks of current, charge a cap, and detect the voltage on that... but that fails the KISS principle
  12. witsender

    Pilot light to detect break in resistive load

    Ummm... I think the transformer+triac also works with DC... I better make a drawing if I can't explain in words... one more go: The DC supply to the resistive load is interrupted due to a fault in the load. This causes a pulse of current in the secondary of a little pulse transformer in either...
  13. witsender

    Pilot light to detect break in resistive load

    put a series transformer in the supply to the load; the other side of the transformer triggers a triac when the current stops flowing; the triac operates an alarm. :)
  14. witsender

    Horticultural led's

    I more often wonder how to cool things, but getting things hot is no trouble. ;)
  15. witsender

    Horticultural led's

    Ahh! We need someone to devise a biological system to take advantage of the uncooperatively emitting Sun? A lifeform that used green light would be interesting. Say, green light eating people. People would live at about a hundredth of the usual rate of one second per second, because they...
See more
Top