What´s this?

[zipzap]

Just came across this. Not much documentation, maybe someone got something to say.
http://www.wiseguysynth.com/larry/schematics/serge.jpg

[Yorky]

Diode gates

[ian-s]

Looks like it might be like a Min/Max module, outputting the highest/lowest voltage on it's inputs. The G2 has one and I think I used it once
You can, for example, separate the pos and neg parts of a waveform for separate processing.

[zipzap]

I have seen min/max schematics somewhere (around here?)
Much more complex. Might as well try it. Could imagine that with this solution you get some trouble that could be solved by ideal diodes.
Do you think those two circuits could be fead by the same inputs, in parallel?

[zipzap]

I tried the peak. Nice. works well. But what i don´t like about it is that only pos voltages are processed.
Anybody know of a shematic for something like the A-172 by doepfer?
It´s also a minmax module, but with no clipping. So you get the min or max out of several signals, no matter how they are polarized.
Would like to have one of those...

[211]

hi zip zap,

Yves Usson did what you need:
http://www.yusynth.net/Modular/EN/MINMAX/index.html

++

[blue hell]

[zipzap]

With the diode going to -12 i could leave it out just the same.
Well, after some trying this came out. It´s working great. Don´t ask me why, i´m asking you...
The pot could be labled threshold. If set below the input signal you get the function i described. Making it higher the bottom of the output is cut off, till it disapears. For a min function the diodes have to be reversed. What suprised me is that the output stays a bipolar signal around 0v. I had exspected some kind of offset from the voltage applied through the pot.
For a min/max module my logic tells me that the inputs need to be buffered (parallel to the circuit shown) and sent to diodes facing the opposite direction.
Then either two sepperate threshold pots could be used, or just one, setting the splitpoint.
With Audio it makes no difference anyhow, min and max sound quite the same. For cv of course this is a cool function.
I´m just thinking: Maybe the inputs should be buffered in any case. Otherwise a threshold voltage set to high (in case of the max module) could creep back the cable and affect what´s before the diode.
Say, in a case like: LFO mods filter, the max module is used so that in it´s upper swing it mods something else as well.

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[zipzap]

And here is the deluxe version. untested. opamps are cheap...
Inputs go to voltage dividers first. That´s a must for the minmax anyway.
Than they are buffered twice in parallel, once for the min, once for the max. I´ve made the threshold voltage controlled, have to check it out, maybe that´s cool. A switch could link the threshold of the two modules to make it superflexible.
And last, in the spirit of our discussion on flexible multitask multipurpose modules, the inputs are summed.
So this module will output the mix of 4 signals, their maximum, their minimum, and it can do vc clipping of the last two.
The clipping can also turn it into a kind of vca/crossfader when one signal is below audiorate, the others above. The slow signal will change volume( can turn it domn completly) and sound.
Still i wonder why with the max module i built the output stays nicely around 0v with threshold at min, since it´s then connected to -12v.

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[blue hell]

[zipzap]

[Scott Stites]

Hey Zip Zap,

I used a Peak/Trough function in the mixer I expounded on so much in the Heavy Metal With XORs thread:

http://www.electro-music.com/forum/topic-11070-25.html

I, too, ran into pitfalls between the concept and actual implementation of the circuit. I used Ken Stone's Analog Logic circuit as the basis for my implementation.

Like you, I too wanted the voltage dividers on the inputs - in fact, the Peak/Trough outputs were to be additional outputs of the mixer (which they turned out to be).

Problem with using voltage dividers I did not anticipate: With no input, your voltage divider will still put out a signal as far as a Peak/Trough circuit is concerned. That signal is 0V.

Haven't checked your schematic out thoroughly yet, but in my situation, when I first tried the circuit - worked fine. One bipolar signal input would send the signal through unaltered. Two bipolar signal inputs would return the min or the max. Great! I added the pots. Now, just one signal input would give only the top half of the signal (for peak) and the trough output was the bottom half the signal. Light bulb over head moment - ground is a higher potential than -V and a lower potential than +V. The voltage divider connection to ground was giving me that ground, whether I wanted it or not.

My solution probably will not work in your case if you're using banana jacks. I used stereo switched jacks. For the Peak connection, I had the jacks switch in -V on the input, so that any reasonable signal would always be above it. For the trough, I switched in +V, again, higher than any expected input. Plugging in the jacks grounded the + and -V input with the stereo ring coming in contact with the ground plane of the mono plug and allowed the circuit to use the input signal, for each input. Works like a charm. I just have to be sure not to use stereo plugs

Cheerio,
Scott

[blue hell]

Oh yes, the mixer means trouble, it connects all unused inputs to virtual ground. In that light ... the buffering input opamps might not be such a good idea either - they will float wherever their input wants to float.

Simple things can be quite tricky sometimes ...

[zipzap]

I´ll have to do some experiments i guess. Can´t follow right now...
I´d like to see Ken Stone´s analogic. Whenever i visit his site the shematics won´t load. Someone experianced the same?
His collection looks so promising!