Invert LFO

[samhay]

I didn't realise you were using V+ of - 5V. If you are using a different type of op-amp to your LFO, then that may be a problem - you can't really run a TL072 or similar on 0/5V. You will have to AC couple your stages if you want to shift V1/2 though. This is problematic as you will need a rather large cap to keep the LOW in low frequency. As a starting point, you could try running the op-amp on 0/9V and leaving Vref where it is. However, you will not be able to pull the LFO wave very far negative before you hit the negative power rail unless you use another single supply op-amp like a 358.

[daverdave]

If you're running the TL071 on +5V to 0V then you've not got alot of headroom, since the output can only get to about 1V to 1.5V of the supply rails. Since you've only got 5 volts ten that only gives you about 2 to 3 volts signal room, I'd definitely run it on +9V.

Have you measured the voltage on the non-inverting input of the inverting amp to see if it's definitely at half +Vcc? Maybe it's being loaded slightly by R3, the 39k resistor in series after the voltage divider, I'd probably get rid of that, it shouldn't make much difference.

[armdnrdy]

I'll try feeding the inverting circuit with 9v and 4.5vref and report my findings.

[armdnrdy]

Nope!

That messed up the original wave as well.

I'm about out of time to experiment. I have to get the decal label put on, clear coat it, and give it enough time to dry before I hand it to him in about 28 hours.

I cut this one kind of close....but I wanted to see if I could make it better! I hate giving up!

Thanks and appreciation go out to everyone who helped!

[armdnrdy]

Well....

Here it is...boxed up and ready to go!
The FL9 is a pretty good sounding flanger. The sweep is surprisingly long.