Shshshshshs on Out put - Page 4 - Electronic Circuits Projects Diagrams Free

aljamri · 3rd January 2008, 04:20 AM

Quote:

Originally Posted by audioguru

The type of FET you use and how it connects depends on the polarity of the POP.

POP ?! the one i heared, how i know its polarity?

audioguru · 3rd January 2008, 04:39 AM

Quote:

Originally Posted by aljamri

POP ?! the one i heared, how i know its polarity?

Look at it on an oscilloscope.

Hero999 · 4th January 2008, 03:53 PM

If you don't have a scope you could connect a pair of LEDs wired in reverse parallel to the output.

aljamri · 6th January 2008, 01:39 PM

Quote:

Originally Posted by Hero999

If you don't have a scope you could connect a pair of LEDs wired in reverse parallel to the output.

Like the attached connection ?

Hero999 · 6th January 2008, 03:05 PM

Yes.

.

aljamri · 11th January 2008, 03:48 PM

I've connected the attached circuit between the output and the Ground and used a 2k

hm: variable resistor set at 50% at the begining and switch on the reverb supply. i've got no indication, gradually i reduce the resistance and try again until reach around 500

hm: where i got the forward bias LED on when i switch the reverb on.

is that enough to know which JFET to be used to stop the pop sound ?

aljamri · 12th January 2008, 07:17 PM

Sorry This is the circuit i used for the test.

audioguru · 12th January 2008, 08:41 PM

You have a positive-going POP when the power supply is turned on. Then you could add a resistor in series with the output and a P-channel Jfet with its drain at the resistor and its source connected to ground. Its gate voltage is 0V when the power supply is turned on so its channel is a low resistance which will attenuate the POP. Then use a resistor from the positive supply to its gate and a capacitor to ground to slowly charge and allow the sound to pass through.

But the jfet might still conduct a little during sounds which will cause distortion. And the series resistor increases the output impedance of the circuit.

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4th January 2008, 03:53 PM	(permalink)
Hero999	If you don't have a scope you could connect a pair of LEDs wired in reverse parallel to the output. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here.

6th January 2008, 03:05 PM	(permalink)
Hero999	Yes. . __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here.

11th January 2008, 03:48 PM	(permalink)
aljamri	I've connected the attached circuit between the output and the Ground and used a 2khm: variable resistor set at 50% at the begining and switch on the reverb supply. i've got no indication, gradually i reduce the resistance and try again until reach around 500hm: where i got the forward bias LED on when i switch the reverb on. is that enough to know which JFET to be used to stop the pop sound ? __________________ Its what your friend in Your mind, what you in your friends mind

12th January 2008, 08:41 PM	(permalink)
audioguru	You have a positive-going POP when the power supply is turned on. Then you could add a resistor in series with the output and a P-channel Jfet with its drain at the resistor and its source connected to ground. Its gate voltage is 0V when the power supply is turned on so its channel is a low resistance which will attenuate the POP. Then use a resistor from the positive supply to its gate and a capacitor to ground to slowly charge and allow the sound to pass through. But the jfet might still conduct a little during sounds which will cause distortion. And the series resistor increases the output impedance of the circuit. __________________ Uncle $crooge