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  1. (*steve*)

    photocell project

    Well there are different types of sensors, but you'll struggle to find one that reduces it's resistance in the dark. Typically the LDR you have would be coupled to a simple circuit to turn in a load when it's dark. The classical circuit could probably be found by googling for "dark sensor circuit"
  2. (*steve*)

    Digital piano won't power ON

    Thanks for the photos. Take a close look at the bottom of those large capacitors and tell me if the stuff around the base looks like glue, or something that's leaked out. I don't like the look of those capacitors. I'd probably replace them even if the piano hadn't failed. I would measure...
  3. (*steve*)

    For Sale: National B&W television Model No TR-5090A

    I know someone who is looking for an analog TV for some genuine 1980's video games, so he may be interested. Photos and some specs would be great.
  4. (*steve*)

    Photos with phones

    The inverse relationship between magnification and DOF is exactly correct. This cancels out the effects of the focal length, subject distance, and the size of the sensor. One other variable is the aperture, and this explains why DOF is likely to improve when the lighting's is better. Reducing...
  5. (*steve*)

    Op amp LM339 help

    And your pull-up is a pull-up, it's not a load. When I asked about a load I was asking about anything else connected to the output (and typically ground referenced)
  6. (*steve*)

    Op amp LM339 help

    Does the external 2.5V source share a common ground with your LM339 circuit? Oh, and PICTURES.
  7. (*steve*)

    Op amp LM339 help

    That's your pull-up, what is the load? Or are you getting these results without a load?
  8. (*steve*)

    Op amp LM339 help

    What load do you have on the output?
  9. (*steve*)

    Program ca3098e ?

    You "program" it by applying a bias current to pin 2. There is nothing to read out. If you're thinking software, you're barking up the wrong tree. This is more like "controlled" than "programmed" in a software sense.
  10. (*steve*)

    Hello can somebody tell me please collector capacitor

    Ratch, I find the errors in your post so egregious that I am forced to ignore it all. So many people write "say" when they more accurately mean "write", and "hear" when they mean "read". There is no sound involved in most of this communication, so "hear" and "say" should be an anathema to...
  11. (*steve*)

    Schottky diode input protection

    Sounds like leakage through the diodes. You would have to disconnect the input to confirm its not coming from there. The 50k pot is loading the output down. Placing it in parallel with another 47k and having the voltage drop by half suggests the source has a pretty high impedance (which would...
  12. (*steve*)

    Schottky diode input protection

    It may be caused by leakage through the diodes. If you just connect a pair of diodes to +5v and gnd, do you see the same thing? If you place a 47k resistor across your meter leads (to reduce the input impedance) does the voltage disappear? Is this voltage causing a problem, or is it an...
  13. (*steve*)

    MOSFET burning up but similar circuit on another board is fine

    Please point me to the specs of that unit
  14. (*steve*)

    MOSFET burning up but similar circuit on another board is fine

    How many solenoids does that one control?
  15. (*steve*)

    Darlington transistor hfe.

    Generally speaking the hfe of a Darlington is the product of the hfe's of each individual transistor. A common pairing is a TIP31 and a 2N3055. A TIP36 is a PNP transistor. For positive linear regulators, NPN transistors are more common. PNP transistors are used in low dropout regulators...
  16. (*steve*)

    Optical triggertesting

    Measure the resistance across the 2 connections to the sensor that if shorted simulate the triggering. Do this with nothing else connected to the sensor. Read the resistance both ways (i.e. repeat the measurement after swapping the meter probes over). Tell me both readings. Does the LED on...
  17. (*steve*)

    MOSFET burning up but similar circuit on another board is fine

    It depends on your multimeter. How accurate and repeatable are low resistance readings? An error of half an ohm due to contact and lead resistance is not really unusual. It would be interesting to see images of one of these commercial drivers that work with this solenoid.
  18. (*steve*)

    Need help with Power Transistor ID.

    Edd's answer wasn't sufficient?
  19. (*steve*)

    Optical triggertesting

    It is possible that you did something to the sensor. It is also possible that you did something to the control unit. How expensive are the sensors? How sure are you that you wired it up correctly? Do you remember what state the controllers LED was in when the sensor is disconnected? Does it...
  20. (*steve*)

    ptc thermistor

    YES YOU CAN. I WOULDN'T, BUT YOU CAN.
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