If you put 2 diodes in parallel, the one with the lowest threshold will be the only one having an effect.
When you see diodes switched in parallel like the Timmy, that's what they're doing.
asymetrical clippers Parallel or Series difference
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Hides-His-Eyes
- Tube Twister
So you're basically picking what kind of clipping diode to use in a timmy?
Testing, testing, won too fwee
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Greg
- Old Solderhand
Yes. If you switch in the single diode, then that's the one that does the clipping instead of the 2 in series.Hides-His-Eyes wrote:So you're basically picking what kind of clipping diode to use in a timmy?
And if you just switch one, then you only affect that side of the waveform (so it's asymmetrical).
culturejam wrote: We are equal opportunity exposure artists.
I'm bumping this topic because I had two similar questions:
I did a suggested mod to my Rat pedal, part of which included replacing the clipping diodes.
On the board was originally two 1N270 or 1N914 diodes (obviously parallel but opposite polarity); the mod had me replace one diode with a single 1N4002, and the other diode replaced with an ON-OFF-ON SPDT switch, selecting between either a pair of 1N4002 diodes (in parallel with opposite polarity) or a pair of LEDs (in parallel with opposite polarity).
So the end result would be:
- With the switch in the first position, there would be in parallel three 1N4002 diodes, but only one with opposite polarity.
- With the switch in the second position, only the one on-board 1N4002 would be clipping.
- With the switch in the third position, there would be in parallel one 1N4002 diode and two LEDs; the 1N4002 would be in the same polarity as one of the LEDs.
So my two questions are:
1) In the first position, would it be equivalent to just having two diodes in parallel with opposite polarity since the signal would flow through the one diode with the lowest threshold out of the two with the same polarity? So this position would just be symmetrical clipping?
2) In the third position, the signal would flow through only the LEDs since they have a lower threshold that the diode? Or is that incorrect and the signal would also flow through the additional diode? Would this position be symmetrical or asymmetrical clipping?
I was thinking of adding an SPST switch in series with the board-mounted 1N4002 so I could switch it out of the path, but now I'm wondering if that wouldn't achieve anything (except in the second position where no clipping would then occur).
Thoughts?
Thanks,
Mark
I did a suggested mod to my Rat pedal, part of which included replacing the clipping diodes.
On the board was originally two 1N270 or 1N914 diodes (obviously parallel but opposite polarity); the mod had me replace one diode with a single 1N4002, and the other diode replaced with an ON-OFF-ON SPDT switch, selecting between either a pair of 1N4002 diodes (in parallel with opposite polarity) or a pair of LEDs (in parallel with opposite polarity).
So the end result would be:
- With the switch in the first position, there would be in parallel three 1N4002 diodes, but only one with opposite polarity.
- With the switch in the second position, only the one on-board 1N4002 would be clipping.
- With the switch in the third position, there would be in parallel one 1N4002 diode and two LEDs; the 1N4002 would be in the same polarity as one of the LEDs.
So my two questions are:
1) In the first position, would it be equivalent to just having two diodes in parallel with opposite polarity since the signal would flow through the one diode with the lowest threshold out of the two with the same polarity? So this position would just be symmetrical clipping?
2) In the third position, the signal would flow through only the LEDs since they have a lower threshold that the diode? Or is that incorrect and the signal would also flow through the additional diode? Would this position be symmetrical or asymmetrical clipping?
I was thinking of adding an SPST switch in series with the board-mounted 1N4002 so I could switch it out of the path, but now I'm wondering if that wouldn't achieve anything (except in the second position where no clipping would then occur).
Thoughts?
Thanks,
Mark
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Greg
- Old Solderhand
So my two questions are:
1) In the first position, would it be equivalent to just having two diodes in parallel with opposite polarity since the signal would flow through the one diode with the lowest threshold out of the two with the same polarity? So this position would just be symmetrical clipping?
Yes.
2) In the third position, the signal would flow through only the LEDs since they have a lower threshold that the diode? Or is that incorrect and the signal would also flow through the additional diode? Would this position be symmetrical or asymmetrical clipping?
The LEDs have quite a bit higher threshold than a silicon diode, so one side of the signal will be clipped by an LED and the other by the 1N4002 diode.
Asymmetrical clipping
1) In the first position, would it be equivalent to just having two diodes in parallel with opposite polarity since the signal would flow through the one diode with the lowest threshold out of the two with the same polarity? So this position would just be symmetrical clipping?
Yes.
2) In the third position, the signal would flow through only the LEDs since they have a lower threshold that the diode? Or is that incorrect and the signal would also flow through the additional diode? Would this position be symmetrical or asymmetrical clipping?
The LEDs have quite a bit higher threshold than a silicon diode, so one side of the signal will be clipped by an LED and the other by the 1N4002 diode.
Asymmetrical clipping
culturejam wrote: We are equal opportunity exposure artists.
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Seiche
- Old Solderhand
so you're saying that one LED is useless?Greg_G wrote:The LEDs have quite a bit higher threshold than a silicon diode, so one side of the signal will be clipped by an LED and the other by the 1N4002 diode.
Asymmetrical clipping
I have a question: why is it that when i use a single diode as a clipping diode to ground at the output, the headroom of the circuit decreases a lot (there is alotta dirt), as opposed to when i use the same kind of diode as a parallel set back to back? I noticed that when i use a switch to switch between one 1n34a and two BAT42 in parallel, the germanium diode produces much lower and much more distorted output than the 2 schottkys(which almost don't change the signal in volume). When i do it the other way around (2 germs and 1 schottky), the germs have much more headroom and dont distort so much whereas the schottky distorts just a tad more, but not as much as the germ before. the signal volume is pretty equal on that second configuration.