Electra Collector Gain Control

[sevenisthenumber]

Any tips on adding a pot to the collector here (47k) as a drive control without the static/noise during adjustment? I love the function, it's working well... The noise is slightly annoying.

[Rob Strand]

Any tips on adding a pot to the collector here (47k) as a drive control without the static/noise during adjustment? I love the function, it's working well... The noise is slightly annoying.

If you are adjusting the value of the 47k then it's difficult to stop the noise without changing something.

If you are replacing the 47k resistor with a 47k pot then connecting the 0.1uF cap to the wiper of the pot then it might be possible to leave the 47k in place and put in another pot  between the 0.1uF cap and the diodes.

I suspect you are doing the first method.

[iainpunk]

Use the fuzz face gain control, but with a 50k instead of the 1k potentiometer, works great on this circuit.



You might want to play with the capacitor value on the gain control, to emphasize higher frequencies so the distortion sounds tighter! Start with 100nf and go down.

[diffeq]

Any tips on adding a pot to the collector here (47k) as a drive control without the static/noise during adjustment? I love the function, it's working well... The noise is slightly annoying.

If you are adjusting the value of the 47k then it's difficult to stop the noise without changing something.

If you are replacing the 47k resistor with a 47k pot then connecting the 0.1uF cap to the wiper of the pot then it might be possible to leave the 47k in place and put in another pot  between the 0.1uF cap and the diodes.

I suspect you are doing the first method.

Would some filtering of the collector supply help to reduce the noise?

Something like this:

[antonis]

As far as "noise" is due to DC through pot, no...

[sevenisthenumber]

Use the fuzz face gain control, but with a 50k instead of the 1k potentiometer, works great on this circuit.



You might want to play with the capacitor value on the gain control, to emphasize higher frequencies so the distortion sounds tighter! Start with 100nf and go down.

Im not sure why but I much prefer the gain of the collector? Any idea why I might? It just feels better to me???

[Rob Strand]

Im not sure why but I much prefer the gain of the collector? Any idea why I might? It just feels better to me???

It changes the DC bias point and the gain.

The DC bias point is the source of the crackle.

One way to vary Collector resistance  value is to use an LDR for RC.   The pot varies the LED drive and that changes the LDR. However that alone isn't the trick. It would probably still be crackly.  What you have to do is filter the DC level off the pot.   That does two things:  It hides the crackle from the pot wiper and it the slows down the rate that the DC changes so it keeps everything under the audible radar.     Much more complicated than just putting in a pot!

[sevenisthenumber]

Im not sure why but I much prefer the gain of the collector? Any idea why I might? It just feels better to me???

It changes the DC bias point and the gain.

The DC bias point is the source of the crackle.

One way to vary Collector resistance  value is to use an LDR for RC.   The pot varies the LED drive and that changes the LDR. However that alone isn't the trick. It would probably still be crackly.  What you have to do is filter the DC level off the pot.   That does two things:  It hides the crackle from the pot wiper and it the slows down the rate that the DC changes so it keeps everything under the audible radar.     Much more complicated than just putting in a pot!

that's a fun idea. Not that complicated I assume...