I`ve got a FROBbing headache.

[GREEN FUZ]

Self inflicted.
After reading all the threads on the Ring Frobnicator and what a finicky circuit it is and how difficult it is you can`t say I wasn`t forewarned.
Like a fool I paid more attention to the ones that claimed to have fixed the bugs and with huge confidence I proceeded to etch the PCB from GEOFEX.

http://www.geofex.com/PCB_layouts/Layouts/frobn.pdf

I`ve used all recommended components CA3080, TLO62, 2N5089 transistor and 3 3mm red led`s as recommended by Martymart.

So far I`ve swapped R11 to 4k7 and R6 to 1M as suggested in a previous thread. I`ve even tried hooking up a 20k trimpot from 9V to the two led`s in series to try to bias them at the recommended voltage (3.2v). Nothing has worked satisfactorily. I know the Oscillator is working because when I fasten a crocodile clip from R13 straight to the output jack I get a strong and pronounced tremolo which can be varied as expected by the FREQ control. However, it is accompanied by a loud thumping which is not much use. By the same means, when switched to RING mode I get a very distinct carrier signal which results in a totally messed up (in a good way  ) guitar signal.

If it`s any help I can provide voltages but I have the feeling I`m on a hiding to nothing here.

I know that at least one person on the Forum has gotten this thing working so if they would be so kind as to share their layout they`d make a (prematurely) old man very happy.

[Austin73]

god I wish I hadn't had this one etched by a friend! Everyone seems to be having problems there was talk about putting a zener diode in front of the power supply as it needs 8.4v or something but can't remember off hand the full details.

I'm sure that isn't any help but thats all I can offer at moment.

PLease let me know how you get on.

Cheers

Aus

[Paul Perry (Frostwave)]

I can't help, except to say, it looks to me as though it is going to be rather sensitive to the supply voltage.
It seems a hard way to go about things.. the 3080 isn't all that quiet at the best of times, so you are likely to hear thumping or breathing when the signal is quiet.
Given that one has a flashing led, using that in a LDR/LED combo might have been easier.

I might add, it's very easy to burn out the 3080 by shorting pin 5 to +.