Phantom Octave

[Vinnie500]

I built a Phantom octave on perfboard and it's my second circuit that has "worked". I don't think it's quite right because the led in the signal path can be pulled out and nothing changes, also it doesn't light up like in the video.

While I was messing around trying to fix those problems I noticed if I shorted the 100uf cap between pins 1 and 8 it sounded alot different, sort of more like a conventional fuzz not so synthie, with more sustain and it did splutter out. I read the electrosmash lm386 analysis but not sure that answered my question... which is what is the capcitor between pins 1 and 8 doing and what does shorting it out mean?

Here is the layout I used also a link to an early round of Q&A when I was trying to breadboard this, thanks again to PRR and Cozybuilder   
http://effectslayouts.blogspot.co.nz/2015/12/fuzzhugger-fx-phantom-octave.html
http://www.diystompboxes.com/smfforum/index.php?topic=115017.msg1067975#msg1067975

[maartendh]

Look at the datasheet. Shorting pin 1 and 8 increases gain, probably you turned the sinus wave of your signal into square waves, So yeah, fuzzy and lots of sustain... Probably also without any damage to the chip. Link a schematic if you want anyone to have a look at the problem with the led, analyzing a vero is a pita. Also have a look at 'what to do when it does not work'

Maarten

[pappasmurfsharem]

This was just posted today


Effects LayoutsSeptember 15, 2016 at 7:37 AM
Yeah, this is probably the culprit. The diode above the 47k resistor should be flipped. Just fixed that in the layout.

[Vinnie500]

Yeah sorry I've been posting the changes in the other thread linked at the top of the page.
There is a schematic there as well but it has the original error with the diode to pin 2 being backwards, I posted to the original layout and that has been changed. Since posting about the diode error I have tested it on the bread board and with that configuration the led in the original layout is backwards. I will try and draw a schematic of my finished version and post it on both these threads.

[Vinnie500]

Ok here is a link with what is on my bread board and IS working, I hope I've got it right.
If you follow the link at the top of the page effectslayout has a schematic link in the comments section now, the LED is round the other way compared to mine. If anyone does end up building this I'd be interested to know if I've down something wrong in the circuit to end up needing the LED in backwards.
I noted this on effectslayout too but I liked a clear led as well as blue. Red and yellow not so much.
Anyway I have a working version on perfboard now so... I'll leave it at that.