freestompboxes.org

Schematic & Finalized parts list -- UNVERIFIED



VR1: A250K (Gain pot)
VR2: B10K (Tone pot)
VR3: A10K (Level pot)

D1: 1N4001? (black diode)
D3, D4: 1N914? 1N4148? (I assume D2 is the power LED)

R2, R3: 10K 5% carbon film
R4: 1M 5% carbon film
R5, R11: 1K 5% carbon film
R6: 10M 5% carbon film
R7, R8: 21k5 1% metal film
R8: 2.15K 1% metal film
R9, R12: 1K 5% carbon film
R10: 220 ohm 5% carbon film
R13: 6.81K 1% metal film

C1: 1000uF 25V electrolytic, polarized radial (Xiahui)
C2: 10uF 25V electrolytic, polarized radial (Xiahui)
C3,C5: 100 pF, ceramic
C4: .01uF 100V 5% (green)
C6: 0.1uF 100V 5% (green)
C7, C8: 220nF 63V (brown)
C9: 1uF 50V electrolytic, non-polarized radial

IC1: TL072CP

Indyguitarist published a BBE GS schem a few month ago, a bit different on the front end. Your schem seems to be more refined, maybe a revision or later version of the GS.

I recommend to mod the 2nd stage for 3 times more output and adapt the values on the the tone control (only to get the same frequency response as before) to make it more useful as a low gain booster.

JHS

Yeah, I saw Brian's schematic but it didn't have any of the voltage dividing section (which is pretty generic) and was also missing a few other things.

I fixed a component value in the schematic above but it appears I can't edit my own posts on this forum, which means I can't update the parts list. Is that correct, and if so, would a moderator be so kind as to update the value of R4 in the list to 1M from 3M?

thanks,

John

Edited... also R7, R8 were wrong, they are 2k15 instead of 1k15

analogguru

Thanks AG. How can you tell by the way? I find these 5-band MF resistors really hard to read. Red looks like brown and I can't tell which end is the tolerance band.

I had the wrong values for C3 and C5 too...by a factor of 1000. The little ceramic caps are 100 pf which I mistakenly converted to .1uf instead of .1nf. Corrected the schem to show 100pf.

Can you tell I'm a n00b?

Excuse me, what's the function of R13? if it's there to block RF it seems to be a little large (I normally use 100R or something like this) , causing quite high voltage drop but, maybe, I'm missing something.
thank you

It limits the current to the +9V pin of the IC, but why so big I don't know. There's also a huge cap (both physically and in terms of capacitance). I suspect this big cap is the reason for the big resistor, but I don't know why both are so large.

Can someone smarter fill me in?

R13 is connected to pin 8 of IC1 .... but pin 8 is connected to V+.

And the other side of R13 is connected to....... the LED, which is fitted below the DC-jack.

R7 is in fact 21k5.

analogguru

Yeah, I had R13 in the wrong place. Thanks. I fixed the schematic.

Can Someone tell me what type of construction this is? I want to get one to mod but wanted to stay away from SMD. Also does it have a full size opamp or one of the small ones like the Cool Cat pedals use. Thanks!

Well I got one on the way. Guess I'll find out soon enough. Anyone know if it has an opamp socket or will I have to remove the opamp and install one?

Great sounding pedal. Works really well with a strat for a basic rock sound. I'll try to get a pic up if anyone wants to see it.

I had one of these awhile back, I was surpised that it was built well and looked to be pretty easy to mod, full size components and plenty of room to work.

Ethan

Lovekraft wrote:I had one of these awhile back, I was surprised that it was built well and looked to be pretty easy to mod, full size components and plenty of room to work.

Ethan

I may sell it. Or I may pull the IC and put in a socket. I have a LM1458 and a Burr Brown to try in it.