Problems with volume circuit

I'm back!

I totally agree about my incompetence and "shots in the dark" ;) I guess I assumed that you thought that the VCA option was a good idea, so I went with it.

Anyway, I have gone with the original idea and used your customized schematic. Now it works as good as it ever will. The sound stops when approaching the antenna, and I'm good with that.

I really don't want you to feel obliged to help me if you don't want to, Fred. I would have been satisfied with your first post only :) I've got one last question though, hopefully easy to answer, otherwise; don't bother ;)

As i mentioned, the theremin mutes when putting your hand close to the volume antenna, but as you remove it, there's a slight "tap- click- pop- (you name it)" sound. Would be really cool to get rid of this, so I could use it for some tremolo-effects without sounding like a popcorn machine :D

I'm doing a short presentation on this project in a couple of weeks. Can I have your full name, so I can give credit to you during this presentation? In connection with this, I will also donate a couple of bucks to your website for all your help!

Thank you!

/Philip

Glad you got something to work - but I really dont know how!  ;-)

I will have another look at it - and get back.. I dont really want to keep pushing this to the top of the list (I get a bit embarrased about having a string of my postings hogging the top!) so will add anything I find out to this posting... Watch this space!

If you could do some measurements of voltages (see Posted: 2/21/2013 12:13:24 AM) this would help me to determine whats going on.. Really havent established anything yet, and need to know if the volume oscillator is running and if the filter + diode are producing a changing voltage, to determine (if anything) what could be done.

Whatever, I am glad I never frightened you away! ;-)

One thing which may help is if you made C4 a lot bigger - try 22n,47n,100n...

But as I have no idea about what is going on and where the operating point of the filter is 'located' (if its even working ;-) any thing could happen by doing the above - but I doubt that it will do any harm..

"I guess I assumed that you thought that the VCA option was a good idea, so I went with it."

I did think it was a good idea - But didnt realise you had insufficient knowledge to handle it. Before even thinking VCA you need to know what voltage change your volume circuit is giving - Once this is working, one can work out the best VCA solution..  The easiest VCA in my view, for bodge circuits like this, is often an op-amp to scale the available voltage, and a H11F1 FET opto-isolator as a current controlled resistor.. With these you can turn almost any voltage change to whatever gain / attenuation you want.

But - you need to create a "dual" supply for the opamp and know a little bit more about electronics than you do to pull this off - unless you really got your teeth into it and studied the required stuff.

Fred.