Hi there,
I've just started bending my SK-1 and need a little advice. On the Casper electronics site, all the SK-1's have a seperate timer module fitted, powered individually witha 9v battery. Is this 'module' a 555 timer chip controlled LED pulser attached to the 'one key play' button via a vactrol? If so, anyone got schematics?
I have searched for ages trying to find this out but haven't found anything relative.
All the best
Timer module for the pitch or timer module for the sequencer tempo?
Timer module for the sequencer!
no need for a vactrol there i guess
I E-mailed Peter Edwards (Casper Electronics) and asked him direct how he did it and this was his reply :-
Rob,
Happy to help... .You've got the right idea, but there's no vactrol needed. ALSO I've stopped using a separate power supply to power the timer.. that was kind of crazy. The right way to do it is to connect the power to the SK1 power supply. The timer is a simple 555 circuit. The output of the 555 (pin 3) goes to the base pin of a transistor ( i think a 2n3904). The outer pins of the transistor (collector and emitter) go to the two pins of the "one key play" button. That's it! If that doesn't work, try some different transistors.
-pete
So, with my hot info. straight from the horses mouth, I set to work. Only thing is it doesn't work properly.
I've made the 555 circuit and it works fine. I hooked it up to the SK-1 power supply and it still works fine. The LED flashes on and off, so far so good.
I attached 2 separate wires to the back of the 'one key play' button, and tested the connection by touching the end of the leads together. It worked fine. Every time I touched the end of the leads together it played the next note in sequence. So far so good.
I connected pin 3 of the 555 to the transistor and the other two legs to the 'one key play' button leads and this is where it goes wrong. Instead of playing the notes individually, in sequence, it played them all messed up and some notes at the same time. Then, when I physically press the 'one key play button, the original sequence I stored has changed and the notes are all messed up. More like wonky play!!
Can anyone help me diagnose this problem? I'm hoping it is only something trivial that needs changing as it nearly works!
All the best
Rob
Have you got it to work yet? I seem to have almost the same problem with my pt-10...
I've shelved my SK-1 for a while, 'cos I'm designing a modular style case for it to house the patchbay and timer module etc. Also I need to spend a lot of cash on all the components needed and I'm skint.
I did try the 'one key play' function the other day, though, after I had made a 555 timer circuit and it worked fine. Although I didn't follow Casper's instructions. The output from my timer circuit was attached via a vactrol to the 'one key play' button. No more wonky play!
a vactrol like led -> ldr? that would change the resistance between the two points, for it to work you would probably need quite a large resistance ldr right?
Yeah, that's right.
This is all still quite new to me so my advice may be slightly inaccurate. There is some great vactrol info here -
http://www.getlofi.com/?p=1978 (http://www.getlofi.com/?p=1978)
In the responses section someone describes using this arrangement as a trigger.
This should provide you with all the info you need.
Good luck.
thanks :) will try it out.
The oddities with the transistor may me becouse of its amplifying abilities...
in hopes this does not come out as too self indulgent (and i do believe it would benifit everybody), i really wish someone would make an up to date drawing of the sk1 board, with all bends, mods, etc, past and present.
there are a few newer ones i am hearing about and i think i would like to try!