[sdiy] Substitute for IMF-3958 ARP 4015 S/H SubModule

[Csaba Zvekan]

Thanks James,

Yes sometimes I a have a hard time expressing myself properly,I'm  
sorry for that .So, pretty much everything works as a direct  
replacement PIN to PIN as you mentioned below except :

> 2) Connect R391 (47k) of S/H clock input to pin 12 of Yves Usson's S/ 
> H.

this is not working since Yves S/H module I believe expects as Square  
Wave signal (then it works) and the ARP is generating that weird  
trigger signal nobody can use but ARP. I even have tried the other way  
around triggering my Modular DIY synth's S/H (same module) from the  
ARP it won't budge.Is there a little circuitry that I could put in  
front of Yves circuitry to accept the ARP trigger signal .Or maybe  
remove some parts  . Because the other  way around I would have to tap  
into R288,R386 to get the clean Square to work.


>> Also if I forget about R391,R392,C119,R390 and just jumper the  
>> whole thing straight from the INT Clock Output then it would work  
>> too.
>
> These do a similar function to C4, D2 and R11 in Yves' circuit. I  
> would just use the original ARP parts and save the bother of  
> replacing this section.

What if I go straight from R391(ARP)  into Yves ( pin12 of U2d's Non- 
Inverting ) would that resolve my issue?

Csaba

On May 29, 2008, at 5:18 PM, James Dunn wrote:

> If I understand you correctly and you just want to replace the 4015  
> S/H module with Yves Usson's circuit, I think I would try the  
> following:
>
> 1) Connect wiper of S/H level pot R319 (100k lin) to R10 of Yves  
> Usson's S/H.
> 2) Connect R391 (47k) of S/H clock input to pin 12 of Yves Usson's S/ 
> H.
> 3) Connect R393 (1k) of S/H output to pin 7 (U2b) of Yves Usson's S/ 
> H OR pin 8 (U2c) if using the slew rate function.
>
>> 2. The Circuit gets a nice Square wave. That ARP pulse stuff just  
>> won't work. I have no Idea why they changed the clock from Square  
>> to _|_ this ??
>
> The transistor in the ARP S/H circuit needs to be turned on for a  
> split second to sample the input voltage, so C119 reduces a gate  
> signal to a trigger signal.
>>
>> Anyhow if I'd remove R321 and C86 from the Noise Source / S/H Input  
>> it will probably work. But then what effect would the 100K S/H  
>> Input Slider have ? HMM...
> As mentioned above, I would just leave them be and you can use R319  
> as a level control for the attenuation of the input signal (ie noise)
>>
>> Also if I forget about R391,R392,C119,R390 and just jumper the  
>> whole thing straight from the INT Clock Output then it would work  
>> too.
>
> These do a similar function to C4, D2 and R11 in Yves' circuit. I  
> would just use the original ARP parts and save the bother of  
> replacing this section.
>>
>> What is the deal with that "ELECTRONIC SWITCH" I never understood  
>> what it 's supposed to do. With the A, B, C Outputs? Can somebody  
>> explain that part of my synth?
> It's a bidirectional switch for audio or control voltages and  
> switches one input to 2 alternate outputs, or two outputs to 2  
> alternate inputs according to the S/H master clock rate.
>
> James

**************
http://www.csabazvekan.com
music stuff
http://www.csaba.ch
electronic stuff
http://www.synthmaniac.com
synthesizer stuff (not fully set up yet)