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Old 1st May 2021, 4:53 pm   #1
Radio Scotland
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Default Signal tracer question(s)

Working on a homebrew signal tracer, The output of the LM741 Is fed to the input of the LM386 via a 0.5uf capacitor but i don't have one, What other values will suffice ? Also the input to the LM741 is via a 1uf NP Capacitor. I don't have one of those either. Would a 1uf electrolytic do the same job ?

See schematic below.


Thanks
Jay
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Old 1st May 2021, 5:53 pm   #2
Chrispy57
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Default Re: Signal tracer question(s)

Hi Jay,
0.47uF is the common preferred value, hard to find a new 0.5uF these days, and not really a critical value component in this circuit.

The NP (non-polarised) input capacitor is specified because you won't know if the input signal has a positive or negative bias relative to that point in the circuit.

It is possible to wire two capacitors in a reverse-parallel configuration to overcome this difficulty. Also watch the voltage rating if you intend to troubleshoot valve circuits with your signal tracer.

If you still need these caps I would be happy to pop some in the post for you.

Cheers
Chris
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Old 1st May 2021, 8:49 pm   #3
Chrispy57
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Default Re: Signal tracer question(s)

Hi Jay,
these two guys should do the job for you. The orange one is Philips 0.47uF 100V and the other a 1uF 50V to couple the op-amps. Just let me have your address and they can go in Monday's post. I'm not bothered about the stamp, what goes around comes around mate.

Cheers
Chris
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Old 1st May 2021, 8:57 pm   #4
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Default Re: Signal tracer question(s)

Quote:
Originally Posted by Chrispy57 View Post
Hi Jay,
these two guys should do the job for you. The orange one is Philips 0.47uF 100V and the other a 1uF 50V to couple the op-amps. Just let me have your address and they can go in Monday's post. I'm not bothered about the stamp, what goes around comes around mate.

Cheers
Chris
Brilliant chris, Iv'e sent you my details via a private message.


Thanks
Jay.


Could a mod lock the thread please...
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Help!! I've been electrocuted by a glass thing that glows
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Old 25th May 2021, 2:43 pm   #5
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Default Re: Signal tracer question(s)

Found a small glass Ge diode in the parts bin, Distortion now gone Happy man Never thought the detector diode would be so critical. Another thing learned,


Cheers all



Thanks
Jay
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Old 25th May 2021, 2:59 pm   #6
ms660
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Default Re: Signal tracer question(s)

So all workie ok so far

The clue for me was the diode type and the absence of a blocking capacitor to the diodes input.

Lawrence.
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