BBE - Green Screamer

sugarinthegourd · Post by **sugarinthegourd** » 21 Nov 2008, 05:37

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

JHS · Post by **JHS** » 21 Nov 2008, 08:46

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

sugarinthegourd · Post by **sugarinthegourd** » 21 Nov 2008, 16:06

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

analogguru · Post by **analogguru** » 21 Nov 2008, 20:54

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

analogguru

sugarinthegourd · Post by **sugarinthegourd** » 21 Nov 2008, 22:35

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?

nooneknows · Post by **nooneknows** » 22 Nov 2008, 11:18

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

sugarinthegourd · Post by **sugarinthegourd** » 22 Nov 2008, 14:23

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?

analogguru · Post by **analogguru** » 22 Nov 2008, 21:05

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

sugarinthegourd · Post by **sugarinthegourd** » 22 Nov 2008, 23:41

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

Pedalpusher · Post by **Pedalpusher** » 09 Mar 2009, 16:59

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!

Pedalpusher · Post by **Pedalpusher** » 11 Mar 2009, 04:49

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?

Pedalpusher · Post by **Pedalpusher** » 19 Mar 2009, 09:31

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.

Lovekraft · Post by **Lovekraft** » 01 Apr 2009, 15:48

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

Pedalpusher · Post by **Pedalpusher** » 11 Apr 2009, 17:19

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.

BBE - Green Screamer [schematic]