Search results

Search Forums New Posts
  1. (*steve*)

    Time reversal transformation

    Over what period of time? You can't do this in real time because that requires you know the state of the waveform in the future. Perhaps you could go with sampling and replaying in reverse.
  2. (*steve*)

    Design of a transistor curve tracer

    Because inductance opposed the change in current. If current is increasing, as it will with the sweep going one way, inductance will work one way. And when current is decreasing, in the opposite sweep direction, it will work the other way. It doesn't matter if you decide to always show the...
  3. (*steve*)

    Replacement for AD630 for the purpose of Lock-in Amplification

    Check out the AD834. Specs go to 500MHz
  4. (*steve*)

    I'm looking for 12v. LED's in red and yellow that cast light like a regular bulb.

    You can search eBay for "COB LEDs". But now you describe (kinda) what you're wanting to do, I think what you want is a "straw hat" LED. These have something similar to an inverted conical depression in the top of them which makes them emit most of the light radially rather than axially...
  5. (*steve*)

    Replacement for AD630 for the purpose of Lock-in Amplification

    The heart of a lock in amplifier is the 4 quadrant multiplier. I would go to my favorite parts supplier and see what 4 quadrant multiplier they have. I know I've seen some that operate into the MHz range, but I've really not give looking for anything really fast. And yeah... Check the...
  6. (*steve*)

    Replacement for AD630 for the purpose of Lock-in Amplification

    Wow, you're telling me that there are signals in my brain at frequencies around 100MHz?!? What will you use as a signal that is synchronised with these signals? For lower frequencies I could see how you found stimulate the brain with a flashing light and use a lock in amplifier to extract...
  7. (*steve*)

    TV Power Supply help

    It's weird. I see the images in Dave's post and also if I manually edit the original post (but not afterwards).
  8. (*steve*)

    Design of a transistor curve tracer

    Well... My curve tracer actually does do a forward and reverse scan of each trace. This allows you to see hysteresis effects (amongst other things). There is an adjustment done during alignment to null out differences caused by wiring inductance. Since this affects both the forward and...
  9. (*steve*)

    Appropriate power supply for 3 LEDs

    If you use a 5V adapter (which are really common) you can connect a 100Ω resistor in series with each LED and then connect each of these to the 5V. The voltage is low enough that even if you connect the LEDs up backward (they won't light up) they won't be damaged.
  10. (*steve*)

    Design of a transistor curve tracer

    The difference in the forward and reverse trace may be caused by inductance in your wiring. Why not use a sawtooth and blank the trace during flyback?
  11. (*steve*)

    Resistor Value.

    I would use a variable power supply to slowly crank the voltage up, but yes, that's the idea. That test will check the low voltage side of the feedback circuit. If the rectifiers are ok and this test doesn't draw excessive current (which may point to some other fault like shorted caps) then...
  12. (*steve*)

    Tek 475 scope

    With the aid of the circuit diagram and/or the PCB layout you should be able to locate other components connected to the leads of the capacitors you can't access.
  13. (*steve*)

    Resistor Value.

    And I would think R18 should be a couple of hundred ohms if it's the one connected to the anode of the optocoupler.
  14. (*steve*)

    Resistor Value.

    I kinda like the idea of replacing that option, but breaking one connection on the led side and keeping it turned on with a 9V battery and an appropriate resistor. If all is well, putting on the power supply should cause it to be completely inactive. It should think the output is at or above...
  15. (*steve*)

    Resistor Value.

    That is generally a good indication that a power supply is overloaded. Let's assume it's part of the feedback. When you remove it, the power supply keeps running because it thinks the output voltage is low. I've accidentally disabled the feedback on an amps and the caps vented. However all...
  16. (*steve*)

    Upper frequency limit of an oscillator

    Fixed it for you.
  17. (*steve*)

    Resistors for IR LED's not working?

    It sounds to me that you are measuring current in parallel and voltage in series. This is exactly the opposite way around. Let's say we just do voltage measurements. With the circuit connected up having the resistor and the LEDs in series and connected to the 5V, measure the voltage across...
  18. (*steve*)

    Internet schematic OK

    @tedstruk can you tell us what you're trying to do. Your circuit 2 posts above looks like nonsense. Are you trying to charge a lead acid battery from a solar panel?
  19. (*steve*)

    Tek 475 scope

    One of these days, when the trauma is a little less, I may tell you a story about what happens when you dive in to repairs too quickly.
  20. (*steve*)

    Finding resistor value/winding resistance

    Well, something has to tell you how the R and the L are connected.
Top