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  1. dorke

    Thermocouple RF Ammeter

    No way! You can not use this "wire" to measure in an RF circuit. Inserting it in an "RF-trace" will immediately create a severe disturbance in the RF transmission line creating a SWR which will change the working condition of the circuit. This is a basic violation of any measurement instrument...
  2. dorke

    Using PWM to regulate power dissipation

    Yes, but the op now refers to #16 in which he only has an L-C in it.
  3. dorke

    Using PWM to regulate power dissipation

    Some scops can do an FFT on the signal, but not the one you are using (Tek 2430A). Yes,use the software in the thread. Hooking up to a PC audio card can be done with the Tek scop output signal(on the rear panel). How are you actually measuring the current,a current probe? To answer the...
  4. dorke

    Using PWM to regulate power dissipation

    No he isn't. Here is why: The circuit as you describe it(#16) is a linear one. In that kind of a circuit all currents and voltages should be pure sinusoidal and at the fundamental frequency only . That should be the same thing in the case of a resonant circuit as well. The distorted current is...
  5. dorke

    Current limiting circuit of LM723

    Welcome to EP. If it is knowledge you seek, you should take the 723 datasheet and learn how the device works. After you do that,and have a good understanding of it, come back with specific questions.
  6. dorke

    Help with 555 device and interfacing with another device

    No problem with long post at all. Driving this rely (which needs about 23mA for activation) should work fine. In this circuit it will use about 12/400=30mA. It will give you the greatest freedom to operate "stuff" since it's contacts are "floating" and will emulate a manual switch in the best...
  7. dorke

    Killing SSR (relays) - Need to understand

    That heat is way too high! Please measure the driving signal to the SSR And a good photo of the physical construction of your circuit .
  8. dorke

    Thermocouple RF Ammeter

    Lower MW band of public AM broadcasting in the 1920s , not to speak of LW band ;)
  9. dorke

    Using PWM to regulate power dissipation

    Well, I don't think your professor is correct on this one. The circuit isn't resonant(it theoretically could be ,but isn't). The inductor isn't the cause of this it is the switching of the load that causes the Harmonic Distortion you notice(THD). You thus have the case of the fundamental...
  10. dorke

    Thermocouple RF Ammeter

    @hevans1944, My main problem with that device is actually with it's name. Calling this an "RF-meter" is kind of a joke.;) Like I said in the previous post,unless we are in the 1920's when RF was something like 500Khz. The problem with that device for measuring RF frequencies is there is no way...
  11. dorke

    Help with 555 device and interfacing with another device

    Please show a drawing of what you did... A picture is worth a thousand words;) Can you measure voltages with a DVM?
  12. dorke

    Using PWM to regulate power dissipation

    I think it shows the generator's voltage at the input to the bridge.
  13. dorke

    Using PWM to regulate power dissipation

    Hi Jeroen, It has everything to do with switching. read this
  14. dorke

    2 transistor circuit input output question.

    Thanks for the link. Much more so for the site...A window to history;)
  15. dorke

    Help with 555 device and interfacing with another device

    "but the hotspot is not controlling it." what do you mean by that is the LED on or off? Can you measure the 1.8V point to ground with the "hotspot" on and off?
  16. dorke

    Help with 555 device and interfacing with another device

    What transistor are you using? It is possible,what happens when you are not touching? Is the Led on and off with the "hotspot" on and off?
  17. dorke

    Help with 555 device and interfacing with another device

    It is very simple: What is the current of the 12V LED you need to drive? The circuit should look like this: It will be good for 20ma LED or lower currents,with that 1k base resistor. What NPN transistors do you have?
  18. dorke

    Help with 555 device and interfacing with another device

    What is the purpose of the 555 in your circuit? If what you need is to drive a relay and a LED-on constantly once there is 1.8V from the "hotspot". You can do that with a single NPN transistor without the 555.
  19. dorke

    PCB Footprint Question

    Welcome to EP. In inches , most footprints of devices are in Inches and so is this connector( 0.1" spacing). And so are PCB wire traces widths in mils. The manufacture gave both for convenience only. Aren't most other devices on your board in inches?
  20. dorke

    LED stays on when it shouldn't. pulling my hair out.

    Yes, but that LED already has an internal resistor it is a "12V LED"
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