A simple distortion effect box could use checking.

[TonyAme]

Hello,
I'm working on a simple effects distortion box for guitar, based on the Elektra Distortion circuit. I could use some others opinions and advice.

1. I have 2 pairs of diodes used for clipping the signal on the output, one pair will be silicon, the other pair will be germanium. Would my selector swith (SPDT toggle) work the way I think it will, selecting one pair (silicon), or the other (germanium)?

2. Also if anyone can point out any problems I might have with the basic layout. *The P-Channel MOSFET is used for reverse polarity protection.

3. I added extra connections to the 3PDT footswitch in case I need to change the wiring of the switch.

Sincere thanks for any help, advice.
Tony

 

[AnalogKid]

The SW1 diode switching is not correct. Notice that when the switch is in the upper position as shown, D2 and D3 still are in parallel across VR1. Expand SW1 to DPDT, and switch both sides of the diode networks.

Add a resistor from the Q2 drain to source, to assure a rapid and complete turn-off.

There are two "D1"s on the schematic.

Since either R5 or R6 always is in the circuit, you can eliminate one of them and move the other to the left side of SW1 (after C3).

ak

 

[TonyAme]

The SW1 diode switching is not correct. Notice that when the switch is in the upper position as shown, D2 and D3 still are in parallel across VR1.

Yes, I see it now. Thank you for bringing that to my attention, really appreciate it.

 

[TonyAme]

Updated schematic with corrected diode pair switching. Sincere thanks.
Tony

 

[AnalogKid]

I must correct myself. With the re-drawn schematic (and the removal of R3), it is clear that SW1 can go back to being a SPDT switch.

To paraphrase MacGuyver: A good schematic will always get you where you want to go.

ak

 

[TonyAme]

I must correct myself. With the re-drawn schematic (and the removal of R3), it is clear that SW1 can go back to being a SPDT switch.

To paraphrase MacGuyver: A good schematic will always get you where you want to go.

ak

Oh boy... I feel embarrassed. Thanks again for that. I was looking at the attached schematic from (freestompboxes.org) when I updated mine (above, with the DPDT switch.) An interesting/versatile way of wiring the clipping diodes.

 

[TonyAme]

Updated Electra Distortion-type schematic, with tone control and spdt clipping diode switching. Thanks.

 

[AnalogKid]

I was looking at the attached schematic from (freestompboxes.org) when I updated mine (above, with the DPDT switch.) An interesting/versatile way of wiring the clipping diodes.

Because it does not indicate that the two switches are ganged, it does give the option of pairing one Si and one Ge diode. In my dealings with guitarists and boxes, no one has ever asked me about this.

ak

 

[Tony Stewart]

What do you expect from this? No input range specs? Impedance?
It's a soft limiter with low gain. I put in a 3-way switch and some extra distortion with a Darlington and added a buffer.
The audio play is only a 1 second max clip and you can play / repeat or change anything such as Collector resistor for more clipping on the bottom with more gain. Click the switch to rotate left.

This version creates 2nd harmonic transistor distortion and some others, odd harmonic diode distortion and is a soft limiter.

A sine wave is not as good a source as a guitar string.

https://tinyurl.com/279dwqdo

 

[TonyAme]

What do you expect from this? No input range specs? Impedance?
It's a soft limiter with low gain. I put in a 3-way switch and some extra distortion with a Darlington and added a buffer.
The audio play is only a 1 second max clip and you can play / repeat or change anything such as Collector resistor for more clipping on the bottom with more gain. Click the switch to rotate left.

This version creates 2nd harmonic transistor distortion and some others, odd harmonic diode distortion and is a soft limiter.

A sine wave is not as good a source as a guitar string.

https://tinyurl.com/279dwqdo

View attachment 149140

Thanks for that info and the simulation, I appreciate it. I was looking for a subtle distortion. The circuit turned out to sound great in that respect.

I just use a guitar and amp to determine the sound, then experiment with different capacitors and clipping diodes. The germanium diodes sound great, very smooth type of distortion.

I will experiment with the mods you describe, very much appreciated.

Thanks,
TonyAm