tr606 Waterston BD pitch sweep

[Rob]

    I have exactly the same problem. I sell the ModBox add on for the TR606, and my
    pitch sweep circuit is based on the one from The Mix. I pulled my hair out for 12
    hours last night trying to get it to work properly. I found that reducing the 220ohm
    resistor to about 57ohms worked. It is a very finicky and stupid circuit. I am going
    to try and come up with a better design, with a proper voltage control, so that the
    bass drum can be played over a 1 octave range from a keyboard. Imagine a 303
    sequencer playing that!
    
    bub
        Ok, heres the deal.. 
        First off, 220ohms or LESS to GROUND is NOT KOSHER!! Unless you want to totally fry something...
        I was alert to this, and I put in 220k there, knowing that print errors do occur at times, and no way trusting 220ohms to ground and to still have the unit survive..
        
        Next..
        Change the cap from 330uf to 10uf, the 220ohm to 1k, and viola, it works..
        Still draws loads of current (enough to have your leds on your 606 flicker) but much better.. 
        I would assume that you could also go to 1uf, and change the 220ohm to 10k, but I dont know if your rc time constant would be there, but that makes it look as though there is a 10k ohm to ground, and that might draw quite a bit less current, which would be good.
        
        I myself am trying to get it to drive offa the accent, since the accent is not all that great anyway, nor is it used much..
        Maybe buffer it with some cmos buffers, and have the option to drive a few more things, like hihat filter, etc...
        
        Rob...
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/19990531/22a200a6/attachment.htm>