ADSR Envelope Generator With State Indicating LEDs

[envytea]

Hello all,

This last weekend I put an ADSR unit together. It is from Ray Wilson's collection. The link:

http://musicfromouterspace.com/analogsynth/norgate_adsr_001.html

So, I have been making Ray's modules for a while, and this is the first that I have had big problems with! After putting it all in place, the testing was terribly disappointing. Nothing works. I have tried a 2 and a 3 volt pulse to trigger it, but there is no output. So, yes, I checked all the polarities of components, goofed solder, and bad traces, but all is most certainly correctly assembled. Has anyone tried this module? What were your results? Any unusual tricks, ideas? I have a multimeter and a oscilloscope on hand, but I am unsure how to proceed in the analysis of the device. Oh, I have switched the ICs too, but there is still nothing.

I really want to post some pictures of my project soon. However, I am having trouble getting pics from camera to computer. I hope I can get this ADSR working! Any help would be much appreciated!

Thanks.
Nick

[RF]

Hi Nick -

I have not built this one - but I'd be surprised if it was an error in the schematic.

Try a higher voltage trigger or gate pulse...

If that's not it you need to do a little detective work.
Pick a spot in the circuit where you know what logic state or voltage you should expect when there is a gate or trigger.. measure there.

If you don't see what you expect the error is before that point in the circuit. If it is there, go a bit further ahead in the circuit and test there.
Once you narrow it down to a section of the circuit, it comes down to looking for the particular component or wiring error near that spot.

Troubleshooting! We all get to do it from time to time. You'll find it....

bruce

[envytea]

Hey Bruce,

Thanks for the suggestions- much, much thanks! I increased the pulse voltage, and I managed to get some envelopes. However, the trigger is still not consistently working. Maybe you or someone else can tell me what to look for as I analyze the circuit. I have looked at some readings on the pulse circuit, and I am not sure what's up. Please refer to link posted above as reference to the following.

Voltages when pulse is high:
@ trigger terminal = 2.3v
after diode (little voltage drop) = 1.90v
after 0.001uF capacitor = 0.00v

Therefore, I am getting no readable voltage at pin 1 on the CD4001. I think this needs to be high to start the envelope generation. So, I am thinking that the capacitors are bad... The voltage on the far side of the capacitor should be the same as prior (1.90v), right? These are just for filtering the signal, no?

Okay, I'll try changing them and see what happens. Thanks.

Oh, as for the sounds I do get when it works, the tone is pretty good, though it'll need some tweaking. It is a good start to getting the sound I want.

[druish]

Being that you checked all your components and such and the chips are installed correctly; why not try and replace the chips? Digital chips are very easily damaged by static and sometimes they are just bad out of the box. Just a suggestion before you go nuts trying to figure it out.