can i connect two independant circuits to the same jack output

druzz · September 20, 2010, 02:22:27 AM

this is a question i ask myself too often without finding a clear answer.

it does ''work'' but i get the feeling it can compromise the integrity of each circuit by exchanging voltages.

i tested it with two atari punk consoles that are mounted in the same case . they each have their own output so i simply connected the two outputs together with aligator clips. it worked , the sounds of the two APC were comming out of the same output but it seemed to change the pitch when i was using just one of them and i undid and redid the connection between the two outputs. so i decided to leave it the way it was with two separate outputs .

but there must be a way to do this clean and simple !!

now i'm on a new project and this question comes haunting me again.

i want to make a deluxe duophonic revenger box with those two circuits in it

i'm going to use a push button for each of the gun ,bomb ,siren ... sounds and put at least a pitch knob for each. and again i was wondering if i should connect them to the same output. well maybe i wont just to be able to pan the two voices but it would be nice to have the option of using a single mono output for both.

so if anybody have tips or related links that could illuminate me it would be awsome

thanks for reading

Gordonjcp · September 20, 2010, 01:33:44 PM

How do you think polyphonic analogue synths work?

Feed all your noise-making devices through a simple mixer, which can really just consist of a bunch of resistors (fixed or variable) and a buffer amplifier. There are loads of circuits on the 'net for them.

Circuitbenders · September 20, 2010, 04:43:04 PM

The search function is your friend

druzz · September 21, 2010, 02:43:29 AM

Quote from: Gordonjcp on September 20, 2010, 01:33:44 PM
How do you think polyphonic analogue synths work?

Feed all your noise-making devices through a simple mixer, which can really just consist of a bunch of resistors (fixed or variable) and a buffer amplifier. There are loads of circuits on the 'net for them.

monophonic synths need mixers too !!

so i need a mixer ... i was trying to avoid that reality. well maybe its a good time to learn to make one

thanks

phantompowers · September 21, 2010, 07:06:25 PM

Don't be scared of making a simple mixer circuit. You should only need two 10k resistors...or something like that.

Gordonjcp · September 23, 2010, 10:54:43 AM

... and a small preamp. Single transistor, two resistors, two capacitors. Dead easy, and then you can say you've built some custom electronics!

phantompowers · September 23, 2010, 12:03:59 PM

To join those two circuits together, wouldn't a simple linear mixer, comprising of just 2 resistors work?

jamiewoody · October 21, 2010, 05:48:52 AM

i hooked up an APC circuit and a 555 tone generator in one box. both to one 1/4 phone jack out.

i even wired it so each circuit has a toggle to switch one, the other or both off. i would think one circuit would not effect the other, since the only congruent factor is the output jack.

but, all controls work for both. even if the other is switched off...go figure...

Gordonjcp · October 21, 2010, 07:53:11 AM

To join those two circuits together, wouldn't a simple linear mixer, comprising of just 2 resistors work?
It would, but you'd lose a lot of output level. Furthermore a lot of these circuits have something on the output coupled back to the input, so any additional loading on the output will affect how it works.

Don't forget that the resistors work both ways, and if you mix two signals together with fairly small resistors (<10k, maybe) then there's a good chance they'll interact. Of course this shouldn't stop you from *trying* to make them interact, just in case it sounds good...

jamiewoody · October 21, 2010, 02:38:04 PM

the best thing is to start breadboarding, hook 2 circuits up together different ways and pick which one you like.

like i said, as much as i want to learn more of the theory behind what i do, and i know i need to...there are some things that seem to make no difference once explained. if it works, it works, and if it works well, then there you go.

Simon Vactrol · January 24, 2011, 01:09:01 AM

Search for "simple channel mixer pcb layout" download that one you like and Etch a PCB(tutorial on you tube)...add component and the trick is done...there are loads of good schematics online.

Bogus Noise · January 25, 2011, 06:13:48 PM

These are courtesy of the excellent Music From Outer Space site, but something a bit like this should do it:

http://www.musicfromouterspace.com/analogsynth/oddsandends.html#SIMPLEAUDIOMIXER

Switch R1 and R2 for pots if you want to have hands on control over the levels.

http://www.musicfromouterspace.com/analogsynth/stereomixer.html

I built the stereo one for summing a few boxes here, and it worked a treat!