Trigger/Gate Question

Wild Zebra · Posted: Thu Aug 31, 2006 9:09 am Post subject: Trigger/Gate Question

I haven't scaled my SL yet but I have an old Yamaha monosynth on loan. It has 2 cv outs and a "trigger out" Well when I hook it up to the soundlab heres what happens:

SL switched to gate, I get a constant tone all the time when I hit the key it "triggers" the AR

SL switched to trigger, I get no sound, if I press a key it only triggers when I unpress the key

So I need a synth that has a "Gate" out, right?

Gate-press key, starts Attack release key, starts Decay?
Trigger- press key triggers the AR,right?

Why am I getting the constant tone in Gate mode.
Pardon my ignorance

Pehr · Posted: Thu Aug 31, 2006 11:48 am Post subject: Re: Trigger/Gate Question

Wild Zebra · Posted: Thu Aug 31, 2006 12:20 pm Post subject:

Good point Pehr. I'll have to check the model and see look it up tomorrow. It certainly asks like that.

bigtex · Posted: Fri Sep 01, 2006 1:16 am Post subject:

If that's the case, just use an inverter.

Wild Zebra · Posted: Fri Sep 01, 2006 12:23 pm Post subject:

Doens't seem to be a S-trigger
http://www.fantasyjackpalance.com/fjp/sound/synth/synthdata/04-cs-5/150_dpi_gif/yamaha_cs-5_14.gif

http://www.fantasyjackpalance.com/fjp/sound/synth/synthdata/04-cs-5/150_dpi_gif/yamaha_cs-5_17.gif
heres some manual scans

huh?

bigtex · Posted: Fri Sep 01, 2006 2:15 pm Post subject:

3V off to 7V on.... hmmmm strange

Well, you could use a comparator to detect the two levels, and get a 0V off, 5V on out of that. Or 12V on. Or whatever you want. I think a comparator would be the easiest way.

If you're unfamiliar with a comparator, it is basically an op amp that has been hooked up in a special way. There are some op amps that are called comparators, because they are designed specifically to work as one, but I've never had trouble using any old op amp as a comparator. Here's how you hook one up:

Use the + input of the op amp for your keyboard's trigger output.

On the - input of the op amp you'll set a reference voltage. 5V would be a good reference, because it is half-way between 3V and 7V. You can easily set this reference voltage with a voltage divider. If you have a 15V supply, you could put a 5k and 10k resistor between ground and 15V. From ground, across the 5k resistor, you'd get 5V. There's your reference.

And here's what you get at your outputs:

When the + input of the op amp is below 5V (i.e. at 3V when the trigger is off), the comparator's output will be low.

When the - input of the op amp is above 5V (i.e. at 7V when the trigger is on), the comparator's output will be high.

Depending on the supply voltage and the op amp's characteristics, your output voltage may varry, but you can adjust that for the output level you want. I think this is actually more of a gate signal than a trigger signal, because from what I infer of that manual scan, it is at 3V when no keys are pressed and at 7V when keys are pressed. A trigger is a short pulse. Do you get a short pulse (trigger) or a signal that stays on as long as the key is pressed?

Oh, and do you have a voltmeter? You'll want one for making the comparator. You won't need it, but you really should have one.

Wild Zebra · Posted: Tue Sep 05, 2006 6:25 am Post subject:

Hey, thanks for the info. It's not imparative that I get it working, but it's nice to know what a comparator is. I may have to make one. Is this something that can be powered with a battery as I don't have a power supply hooked up.