[sdiy] Help with transistor switches

[Plutonique9]

Not that anybody's answered, but i've just managed to solve my 
problem regarding triggering "slower scanned" pads of my Zoom 
SampleTrak, the issue being that the 808 pulse was to short to 
register the transistor based switches across the pad contacts. I now 
managed to have the pads respond stabily to triggers by borrowing 
from the Tr-606 circuitry. Basically a 1uf cap and a 2.2 meg resistor 
going to ground at the base of the transistor switch + a diode, a 
very crude decay envelope, but simple and passive like i needed. The 
circuitry was based around Q35 of the 606 schematics, this was one of 
the Env.'s for the cymbal.

Seeya



On Sat, 19 May 2001 06:19:32 GMT, Plutonique9 wrote:
>Hello,
>Last week I picked up a Zoom Sampletrak Phrase sampler, and, well,
>I've already started to modify it. So far I've had sucsess 
triggering
>the samples from my 808 trigger outputs buy adding a transistor
>switch across where the sample pad contacts are. This is ultra
>smooth, and necessary for the machine, as the midi input only offers
>"gate" control over the samples, ie. no triggering one-shot or
>re-triggers from midi.... yes, pissed me off this did, but now this
>works excellent because the 808 makes an excellent master controller
>for triggering loops and samples on the SampleTrak. Also, because 
the
>onboard sequencer only records note data from the onboard pads (not
>via midi), this opens up a more powerful way of inputing data into
>the sequencer.
>
>The switches i built were taken from the doepfer FAQ, instead of the
>switch going to ground though (for the s-trig convertor), it close
>the two contacts of the pads.;
>
>http://www.doepfer.de/faq/gen_faq.htm
>
>So, triggering the sample pads works like that great, however some
>other pads that i want to add trigger inputs to control are not
>working. I'm guessing that this is because the onboard "Sample pads"
>are scanned alot quicker than these other pads, those being non time
>critical, so i'm thinking the transistor switches for these are too
>short. So I need to somehow lengthen the time of the switch a little
>more, so that external triggers are registered. I'd hopefully like 
to
>avoid any "extra" circuitry, other than passive components, in an
>effort to keep this simple and cruisy, that is unless it is
>absolutley necessary to use an IC (like a 555).
>
>The need for this modification, is to add something to the 
sampleTrak
>that i enjoyed on my old Roland MS-1. It had a trigger input to 
start
>and stop the "sampling" recording, and with my 808 side by side, it
>made recording seemless beat loops a breeze, because manually 
setting
>a loop on a phrase sampler is quite tricky.
>
>The second trigger input was to trigger the "play/stop" button of 
the
>onboard sequencer.
>
>So these two don't respond to the same meathod of a transistor 
switch
>across the pad contacts, as in the doepfer FAQ. So, any way to 
easily
>extend the time of the switch?
>
>Thanks for any help
>
>Seeya
>
>
>
>-- Plutonique9, Plutonique9 at symbiocom.com
>
>http://www.mp3.com/Plutonique9


-- Plutonique9, Plutonique9 at symbiocom.com

http://www.mp3.com/Plutonique9