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DIY Stompboxes => Building your own stompbox => Topic started by: Mark Abbott on April 06, 2004, 03:17:31 AM

Title: 70's pedal circuit
Post by: Mark Abbott on April 06, 2004, 03:17:31 AM
I recall sometime ago people here were experiementing with the Fulltone 70's pedal, I remember a clipper circuit was also mentioned.

If someone could be so kind as to forward me a copy of the circuit I would appreciate that.

Thanks for your assistance.

Yours Sincerely

Mark Abbott.
Title: Cmon now somebody knows something!
Post by: Mark Abbott on April 08, 2004, 12:05:47 PM
What no takers?

I remember someone having a circuit for this thing.

Yours Sincerely

Mark Abbott.
Title: 70's pedal circuit
Post by: ErikMiller on April 08, 2004, 05:08:41 PM
I thought the '70 was a silicon Fuzz Face....
Title: Fulltone '70s
Post by: Russ on April 08, 2004, 05:22:44 PM
It is. I'd love to have a copy also, if someone would be so kind.
Thanks, Russ
Title: 70's pedal circuit
Post by: Dai H. on April 08, 2004, 07:24:42 PM
hi, it's at the Yahoo schematic_trading group
Title: The group?
Post by: Mark Abbott on April 13, 2004, 06:43:48 AM
Dear Dai

Could you give me the address of this schem trading group?

Much thanks.

Yours Sincerely

Mark Abbott

P.S. Someone did send me a copy of the circuit which I really appreciated.
Title: 70's pedal circuit
Post by: cedric on April 13, 2004, 09:45:08 AM
pic is here:
http://f1.grp.yahoofs.com/v1/UOR7QCpeFxryQr0EIuFtaZaDTBKSzZEsSZ9xTp2mVssIJ83yJCPnkjxQoFSXFnReWg0NOHW6TBG2iS3KYqKfyE8OT-8h4QPwIiju/Fulltone%20%2770.GIF

and the group is here:
http://groups.yahoo.com/group/schematic_trading
Title: 70's pedal circuit
Post by: phillip on April 13, 2004, 03:31:10 PM
Here's a PCB and Layout for the Fulltone '70 that I drew a while back when I was going to build it.  I got distracted with other projects and never got around to it, but the layout should work fine:

(http://axiseffects.home.att.net/misc/1970fuzzlayout.gif)
(http://axiseffects.home.att.net/misc/1970fuzzpcb.gif)

I'll leave them posted until midnight tonight, then I'll have to take them down.

Phillip
Title: 70's pedal circuit
Post by: Phorhas on April 13, 2004, 05:30:11 PM
Perhaps a silly question but... how does it sound?

BTW what R the original transistor used by fulltone?
Title: 70's pedal circuit
Post by: phillip on April 13, 2004, 10:35:13 PM
The one that Luke traced out had a pair of 2SC828 transistors, which have a B-C-E pinout.  There's nothing really special about those though...a medium gain transistor like the 2N4401 will work fine in its place.  I have heard of other versions that used a BC108 and BC183L combination...not sure which went in what position.  I would think that some of the European-made audio transistors like the BC108s or BC109s would be even better sounding in there than the 2SC828s

Phillip
Title: Like FF
Post by: petemoore on April 14, 2004, 01:00:22 AM
IIRC the 70 enjoys the lower gain transistor in Q1.
 and 4401 should be good. I ended up either with 4401 or NTE123, in Q1 but I think a Tin can 2n2222 might be a good suspect. Q2 is a BC 109 in mine.
 I think it sounded good, Fuzzy and hard driving. Also I used a 2k gain knob...the extra knob actually works pretty neat, adds gain and midrange if Im not mistaken.
 Very nice, actually a little mean buggar. aggressive. I think would do well in a Blue Cheer tribute band. Been a while since I tried that one out.
Title: 70's pedal circuit
Post by: dev on April 14, 2004, 01:52:43 AM
How do the diodes affect the 70's pedal sound?  similar to the common diodes to ground or is it more subtle?  I've never seen diodes in this configuration, is this found in some other pedal?  
thanks Dev
Title: 70's pedal circuit
Post by: nightingale on April 14, 2004, 02:52:47 AM
i can't see the schem~
would someone mind emailing it over to me?

ryansusa3@msn.com

thanks,
Title: Re: The group?
Post by: Dai H. on April 14, 2004, 07:00:28 AM
Quote from: Mark AbbottDear Dai

Could you give me the address of this schem trading group?

Much thanks.

Yours Sincerely

Mark Abbott

P.S. Someone did send me a copy of the circuit which I really appreciated.

Cedric beat me to it, oh well.  :wink:

re: the sound, I converted my Si FF to the circuit shown, and I liked it. More like a Ge one, I guess. Single notes were real fat and synthy, is how I recall it last time I used it. I used what appears to be an alloy junction Ge and not those (point contact?) glass ones like 1n60, etc. The exact type seems to make a diff., or perhaps the gains were accidentally correct w/the ones I like(?). The normal Si FF sounds a bit flat to me compared to  the Ge version.
Title: 70's pedal circuit
Post by: Phorhas on April 14, 2004, 11:08:11 AM
Thanx Alot for everyone responding :)
Title: Diode?
Post by: petemoore on April 14, 2004, 12:13:50 PM
Oh yes the diode...I didn't get much yardage with that thing, and ended up leaving it out...synthy...yepp...reall gainy and Fuzzy though..
Title: transistor gain in FF cct.
Post by: Mark Abbott on April 14, 2004, 11:39:49 PM
I have a Schaller Fuzz that is a copy of a Si FF, it used BC239C's, I think that they have a gain of roughly 500, (according to my multimeter.)

To get to the point, they sounded dreadful in this circuit, a friend who has a Dunlop Jimi Hendrix FF also thought this pedal sounded dreadful, I can't remember what transistors were in the circuit, but I do remember that they had a high beta.

Yours Sincerely

Mark Abbott
Title: 70's pedal circuit
Post by: phillip on April 14, 2004, 11:44:33 PM
There are some very low gain Silicon transistors that have the promise of sounding pretty good in a Fuzz Face circuit.  Jack Orman used one of those low gain types in his YAFF, the 2N2369, which has a gain between 40-120.  Mouser has ran out of stock of that part number, I think because the companies have "obsoleted" them.  Mouser still has the PN2369A though, which is pretty much the same.

Phillip
Title: 70's pedal circuit
Post by: jimbob on April 15, 2004, 01:39:32 PM
phillip- i think im gonna build that sucka in the next few days.. has it been tested to work yet? or been built yet? Looks great though! nice work!!

jim
Title: 70's pedal circuit
Post by: phillip on April 15, 2004, 01:49:16 PM
I haven't built it yet, but I plan to at some point!  I've checked the PCB layout many times and it looks like it's ready to go.  

Phillip
Title: 70's pedal circuit
Post by: dev on April 15, 2004, 09:59:30 PM
What are the values for the three pots and also the trim pot on this pedal?
Also, would adding an input pot help with any signal chain issues latter?
thanks
dev
Title: 70's pedal circuit
Post by: phillip on April 15, 2004, 10:10:10 PM
Volume pot = 250KA
Fuzz pot = 1KB
Mids pot = 1KB
Trimpot = 5K

Phillip
Title: 70's pedal circuit
Post by: RedHouse on April 22, 2004, 12:23:18 AM
phillip

Do you have the schem-o for that 70's pedal?
(for the layout you posted above)

Or I guess I should ask, could I get the schem-o for it?
Title: 70's pedal circuit
Post by: phillip on April 22, 2004, 12:43:57 AM
Here it is

(http://axiseffects.home.att.net/misc/1970fuzz.gif)

Phillip
Title: 70's pedal circuit
Post by: RedHouse on April 23, 2004, 12:05:28 AM
Thanks Phillip!.
Title: 70's pedal circuit
Post by: Dutchie on May 02, 2004, 06:41:25 AM
Hmmm fished behind the net...grrrrr

Can anybody supply me with the scematic

Any or all fulltone schematics are welcomed ;)