anyone in here ever built their own modular synth modules?

[earl parameter]

http://www.electro-music.com/forum/view ... 77&start=0

[rjd2]

crashsick, your stuff looks GREAT! very impressive. i hope to make some modules someday that look that nice.

ok, here's a specific question:

i need to buy a voltage converter that will do the following-
1-turn 0V into 15V(more specifically, anything over 5V), and
2- 15V into 0V.

my prophet 5's gate/trigger function works note on=15V, note off=0V. this is backward from "normal", most synths function note on=0V, note off=4v/5v/15v/etc. i want the prophet to work "normal" as a CV controller.

i've googled my brains out and cant find a product that would switch (invert?) the voltages, and yet im told by some of the folks at electro-music.com that such thing exists as an outboard converter that i can just plug right into.

anyone ever come across this? maybe im searching/googling with the wrong keywords?

[earl parameter]

just rig up an inverter. you can use a CD40106. it could not be simpler, which is probably why you can't find anything.

just power the chip to 15v add a 10u (or larger) cap and a 100n cap between the power rails and just run your trigger into and out of one single stage and your done. but make sure you get a "CD" 40106 as some models will not run on over 6v

and thanks


steven

[rjd2]

thanks much steven.

so that inverter will put out 15V(or some positive voltage) when 0V is put into it?

[earl parameter]

no not like that, guess i wasn't paying attention. sleep

the simplest way i can think to do it would be to have one stage for the 15 to 0 conversion and another for the 0 to 15. all on the same chip and then just stuff it all in a box with 4 jacks ( 2 pairs of ins and outs) and power

for the "input 0v get 15V out" version take a 1M resistor from the input and have it attach to the positive rail.

for the other "input 15v get 0V out" have the 1M attach to ground.

you can certainly add a switch to flip the 1M around so you can just have one stage work for both conversions but jacks are cheap, the 40106 has six stages and everything else is there so why not make 3 of each so you can use them all at once.

http://pdf1.alldatasheet.com/datasheet- ... 40106.html

make sense?


i love that you are fearlessly diving into this stuff but, if you don't mind me saying, i don't like that you mod the synths themselves. these things you have are rare treasures and should be treated as such. there are not many elkas, cs80's and prophets left in the world. i say this with all due respect of course



steven

[rjd2]

thanks for that help, steven. i appreciate it. if i get off the ground with this other project and need it as a CV controller, i will do up an outboard piece like you suggested.

and no, i dont mind you saying so about the rarity thing. i appreciate your concern-its a good reminder. i DEFINITELY dont want to be the guy that is all cavalier about having access to some very rare instruments, and doesnt treat them as such.

FWIW, i have done VERY few actual modifications on synths. i mostly have just tried to keep them working, fully restored,recapped, and properly calibrated. the synthex thing was my biggest endeavour, and also quite sobering.......

i basically spent hours and hours trying to make that pitch bend mod work, only to find out that the issue of load on the master joystick's resistor was essentially insurmountable. i then spent more than a few hours just retracing my steps, to bring them back to stock, and weeks looking for parts.(but if you had heard what they sounded like in tandem, you would've dreamed of being able to pitch bend them together as well!!!!!)

i have finally gotten both synthexes back to 100% stock functionality, but not without a lot of work and worry, and i regret to this day doing ANYTHING to the chassis of one of them, albiet however small and un-noticable.

when i got my CS80, i didnt even turn it on until the PSU was recapped. i made sure the PSU output voltages were within .1V of where they should be. as soon as the hood goes up, my static wristband goes on, even if im just tuning. i try to be EXTREMELY careful around it, as well as anything "rare". but i also know that im nowhere near a tech-im all to aware of my deficiencies in this field!

at the same time, i buy synths to play them/record/make albums with. i dont want to have a museum or something, where stuff doesnt get turned on. i fully believe in them being used and experienced. and on the rare occasion that there is a "functionality/compatibility issue" with something, i have considered modding them to be more useable. maybe not always the most prudent decision.

i appreciate your concern. i definitely dont want to seem whimsical about having access to some amazing and rare instruments, and apologize if i do. i highly value them(obviously- have dropped some coin on them!), and try to keep them in as close to "factory new" as possible, and in tune and calibrated. people like yourself have helped me do this! i hope that when i have arthritis in 30 years, someone else can be playing these things.

(besides, im setting my sights on a new project at the moment, so it should just be occasional upkeep on this stuff from here on out.)

[earl parameter]

good to hear.


steven