Lovepedal Silicon Fuzzmaster

rmroza · Post by **rmroza** » 06 Jun 2012, 00:19

...ok, I just reviewed as a second set of eyes the PCB layout to schematic. They look good. A couple minor things...the diode D1 is actually D9 on the PCB layout, BOM, and original. Also after R11 on the CB C13 comes first, so on the schematic C5 and C13 would be swapped (not an expert, so no sure if that matters).

The PCB layout may need one amendment, bt it won't affect the schematic or vero here. I just noted that I have R4 to ground before going to the switch, but don't think that is correct. Likewise, not sure why the switch 7 and 8 position go nowhere, so the switch would go to nowhere and no where or switch to nowhere and thru R4 to the the switch! That doesn't make any sense. Pin 8 of the switch probably should go to ground and like I said remove ground from R4 and just flow from the switch and if ground thru the resistor to the LED!

Again, no issues with the schematic or vero layout!

Ok, off to de-populate and make the new board!

Eqinox

IvIark · Post by **IvIark** » 06 Jun 2012, 06:53

Yes I'd figured there was still an error with the LED in the PCB layout, lug 8 of the switch needs grounding and R4 isn't grounded or the LED will always be on, as per the schematic. The position of C5 and C13 on the schematic don't matter, they're both directly connected to the supply rail and ground.

rmroza · Post by **rmroza** » 06 Jun 2012, 12:22

Thanks IvIark

Looks like it should be a go then! The parts I ordered should be in tomorrow, so I should be able to slam it together after work!

Thanks for everyone's support!

Equinox

rmroza · Post by **rmroza** » 06 Jun 2012, 23:20

@ Nocentelli - Yes, changing bias I think it in the design.

Equinox

rmroza · Post by **rmroza** » 07 Jun 2012, 00:58

Ok, old board de-populated and new board populated with leads. I just need the pots tomorrow. Off to do graphics and get the box ready. Jimi goes on this one fo-sho!
I added the two columns and used the Bourns 3386 trimmers as I said I would. I used all caps and everything as the original as-is. We'll see what happens tomorrow. Enjoy!

Equinox

rmroza · Post by **rmroza** » 08 Jun 2012, 12:17

Good morning!

Did anyone verify this yet??

I slammed it together last night, but it didn't work! I finished late and had to go to sleep, so no time to troubleshoot.
I'm pretty busy until Sunday now, so it will be a few more days on my end.
Let me know. Else, I will have to troubleshoot and desolder the entire board again one last time. I hope it's just a solder bridge or something on my end.

Equinox

IvIark · Post by **IvIark** » 08 Jun 2012, 12:39

Yes Ravian Arp made one on my blog.

HHR18 · Post by **HHR18** » 09 Jun 2012, 00:12

IvIark wrote:Yes Ravian Arp made one on my blog.

Yep, I did indeed verify it but I build it using the original layout though!

IvIark · Post by **IvIark** » 09 Jun 2012, 00:18

Oh it's you!

Yes but the original layout with that wire link is exactly the same as the new layout, so I'm comfortable enough that if one works the other will. Equinox, post a higher res front and back pic of the board just so you can get a few extra sets of eyes looking at it for you.

rmroza · Post by **rmroza** » 09 Jun 2012, 10:19

Cool. Glad it worked and it verified! What do you think?? I like it!
Yeah, it's probably just a solder bridge or something, but let me take it apart and if needed post pic(s).

EQ

rmroza · Post by **rmroza** » 09 Jun 2012, 12:51

VERIFIED!

I had the 470R is r.2 going from Row A to Row E instead of Row D. My bad

Works perfectly. Sounds great an is quiet!

Equinox

Yonatan · Post by **Yonatan** » 17 Jun 2012, 19:12

Just got it working on a breadboard. I didn't get to play around with it too much yet, but sounds very nice. I haven't built any FF type circuit before, but wow is this touch sensitive!

At first I left out the 220uF filter cap, because I didn't have one. Big Huge Mistake! The thing non-stop howled and oscillated like crazy! I thought this cap was only needed for noisy power supplies or something, but then I started searching for info and realized it has something to do with getting certain negative ground PNP circuits to avoid this behaviour.

One question: How subtle, or not, should the blend pot be? And should it be noticeable mainly at higher gain settings?

rmroza · Post by **rmroza** » 20 Jun 2012, 04:02

yes, the blend knob is noticable at high gains. it shifts and changes the tone and bias i believe!

EQ

Yonatan · Post by **Yonatan** » 20 Jun 2012, 08:32

Thanks, I have the Blend control working nicely. Now I just need to get a reverse log pot for the Drive control. I only have a Linear pot for now, and it doesn't do anything until the end of its range. Or maybe it's time to finally read the geofx article that talks about tapering resistors.

Nocentelli · Post by **Nocentelli** » 20 Jun 2012, 10:28

Yonatan wrote:Or maybe it's time to finally read the geofx article that talks about tapering resistors.

Definitely worth a read, but in a nutshell, I think you could get a decent reverse log 1k drive pot using a 5k linear pot with lug three connected as per the schem, lug 2 via a 1k2 to ground, and lug 1 to ground.

Yonatan · Post by **Yonatan** » 29 Sep 2012, 19:28

This is still sitting on my breadboard, and I noticed that the different versions of the schematic seem very different around the path to V+ from the emitter of the 2nd transistor.

Can anyone explain the difference between them?

The original schematic posted (no revision marked on it) looks like a typical fuzz face circuit:

: a.gif (3.2 KiB) Viewed 2593 times

The last one posted (marked revision 3) looks different. The cap is in series with pot, and there are resistors in parallel with cap/pot:

: b.gif (3.15 KiB) Viewed 2593 times

Nocentelli · Post by **Nocentelli** » 30 Sep 2012, 16:33

The first one is identical to a standard fuzzface (DC bias fixed, AC bias variable between an effective 1k and zero k), the second gives a DC bias variable from 1k5 to 1k and an AC bias of 500ohms to zero ohms.... I think.

Yonatan · Post by **Yonatan** » 24 Dec 2012, 18:28

rmroza wrote: Q1:
1 - 1.46V
2 - 6.62v
3 - 7.24V

Q2:
1 - 6.62V
2 - 7.48V
3 - 7.93V

Still have this on the breadboard. I want to perf it, but one thing is bothering me. Instead of 1.46V, I'm seeing a few volts (can't remember, 3 or 4 I think). Any idea why? I built to schematic except that I used BC212 instead of 2N3906. The circuit sounds fine to me, though I don't have anything to compare it with.

Nacho5 · Post by **Nacho5** » 14 Aug 2014, 03:25

Guys! Someone used GE PNP? I build this pedal with Silicon bit i hace some GE transistor to try

IvIark · Post by **IvIark** » 14 Aug 2014, 11:13

Yes give it a go, it'll be interesting to hear what you think of the results

Lovepedal Silicon Fuzzmaster [traced]