EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: wedgetail on July 13, 2020, 01:44:11 pm
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For various reasons I have a very bad time getting this little circuit to work, now at least I believe I have the DC situation working but I must have missed a point because I can't get a sqeek out of it.
I have a soldered breadboard version. As a training exercise I have used kiCAD to make a form of layout, I will attach plot of the schema with some measurements.
Because I have two function generators gone on strike, BWD minilab and hp208A both dead output, at the same time I needed to check some pot cores so I made a quick check on the internet. Stumbled on the simple circuit here:
http://www.discovercircuits.com/DJ-Circuits/DAJ-List-Titles-circuits.htm (http://www.discovercircuits.com/DJ-Circuits/DAJ-List-Titles-circuits.htm)
Any comment would be most welcome.
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Try to increase R1 to 1k. If nothing, try to increase supply voltage a little. It should work, if no, maybe there is some mistake.
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Manul
Thanks for posting.
First you were correct, I made a mistake. The output resistor and the drain resistor had been exchanged. I had only a 1k ohm in the drain. Each time I turned the board over to check the component side I failed to notice the values on the resistors.
Second I also found on the internet a short youtube video dealing with exactly this same circuit, this made me believe too that my circuit should work. It worked ok as an amplifier just not oscillating. Here is the link:
https://www.youtube.com/watch?v=Ff5xOENID7w (https://www.youtube.com/watch?v=Ff5xOENID7w)
I have inserted a 6k8 ohm resistor and it works from 9V to 19V on most of my coils, got some ferrite material (ring cores) which I can not get to run but depends on the inductance. I think they were from old equipment used as suppressor coils on mains leads.
I have also increased the source resistor to 1k ohm and it works fine with that as well, left the 10k ohm resistor in the output.
All well for the time being.
:)