[sdiy] Can I use an LM13600 in place of an LM13700 ?

[Aaron Cram]

TooManySynths wrote:

>I'm thinking of adding arron cram's Portamentiometer,
>a neat combination vc portamento and LFO, to my panel.
>I have an unused section with four jack holes and a
>pot. If I replace one of the jacks with a switch it
>will work just fine.  Arron's circuit uses an LM13700,
>but I only have LM13600s.  Since I don't want to make
>a parts order for one OTA, I was hoping to substitute.
>It does not appear at first glance that the additional
>features of the LM13700 will make any difference.
>
>The other candidate for the same space, is Jurgen's
>combination sample and hold, glide, glide and hold,
>which will also fit if I leave off the output level
>adjust control.
>
>Opinions ?
>

I havn't tried a 13600, but I don't see any reason why it won't work.  I 
would suggest building the circuit on a breadboard before making a 
module out of it.  Then, patch it into your existing system and see if 
it works for you.  In my system, it stays in tune very well.  However, I 
did have problems with HF oscillations, I had to shield the wires that 
connected the front panel switch. Another thing to keep in mind is that 
the portamento is going to be LINEAR.  It sounds a bit different than a 
303.  (Again, try it and see if you like it.)  Finally, to build a 
simpler version for testing, just leave out all of the circuitry "above" 
the 10K resistor coming from the OTA (on the schematic.)  The two 
trannys and all those resistors are just there to make the response 
exponential and mix/bias the CV inputs.  (Leave the 10K one there 
though, it keeps the "magic smoke" inside your OTA!)


-Aaron