PIG Booster

Branimir · August 17, 2006, 12:02:17 PM

This is by no means some kind of supersounding booster, but anyways here is a little story how I found it useful.

I was running my diy russian muff into my orange clone type amp with the bmp's volume maxed out, so the pedal was driving the preamp into distortion.

Then, I stuck a tremulus lune and accidentally turned the depth pot to the minimum (no tremolo efect, just signal passing through), and turned the volume pot on the tremulus lune a bit too high. The amp was already going all the way, so there was no volume boost, instead I got even more preamp and poweramp distortion.

It was like, "holy cow, I've got my mids back! hehe", The character of the muff was a bit more grainy and less mid scooped, so I knew I had to build a seperate boost pedal, to save the Tremulus for it's primary puropse.

So I took a look at the lune's schem, and noticed that it was just a single TL072 with a gain control on the second opamp, great, I'll substitute the ldr with a 100ohm resistor, just for the sake of not connecting first opamp's output and inverting input of the second opamp directly. I have no clue about total gain of the booster, but if it can drive my amp harder than my BC549c built muff, then sure there's lot of ouput going on here...

I know it's lame, but here is the board.

The board is not verified, I'll build it in the next couple of days, but I can't see a reason why it shouldn't work.

oldrocker · August 17, 2006, 07:16:47 PM

Let me know how it turns out. I wouldn't mind trying an opamp buffer for my relay bypass pedal I just built.

KerryF · August 17, 2006, 07:21:14 PM

Nice... Do you have a schematic for what you came up with? I will make a Veroboard layout for it if I can have the schematic.

Branimir · August 17, 2006, 07:52:51 PM

This is just the part of the schem of the tremulus lune from tonepad!

I ommited the ldr, and placed 100ohm resistor, that's it. I figuered, if it sounds good, I'd better build the same thing (without the LFO part of course).

Of course, this is just my impression, I have no clue about how it'll sound on other amps.

KerryF · August 17, 2006, 07:55:27 PM

ok give me a sec and i will come up with a vero layout so i can try it on breadboard...

Seljer · August 17, 2006, 08:08:39 PM

the first half of the opamp is setup just as an inverting buffer, the second half gives up to 48dB of gain depending on how you set the pot

KerryF · August 17, 2006, 08:28:31 PM

Theres the veroboard layout. Not yet verified and could be wrong. I havent yet done layouts for ICs or OP Amps so yea... Check it out for me.

MartyMart · August 17, 2006, 08:42:29 PM

Check your pinout for the dual opamp :
Left side down from top "dot" it's 1-2-3-4
Right side "up" from bottom is 5-6-7-8 !!

MM.

QSQCaito · August 17, 2006, 08:42:55 PM

Quote from: call1800ksmyazz on August 17, 2006, 08:28:31 PM

Theres the veroboard layout. Not yet verified and could be wrong. I havent yet done layouts for ICs or OP Amps so yea... Check it out for me.

Am i dumb??

I just can't see any output, did you miss that??

DAC

KerryF · August 17, 2006, 08:44:04 PM

yes i missed that... comming right up... is everything else right? oh yea marty, thanks i will fix the op amp.

QSQCaito · August 17, 2006, 08:51:10 PM

This may help:

Bye! It's a TL072, and some other opamps have the same pinout.

bye!

dac

KerryF · August 17, 2006, 08:54:46 PM

Updated. Sorry. Im a noob with op amps....

And this isnt the exact schematic you used. Your layout is a bit different. And also, do the "Rb"s just go together? Or what do they do?

Branimir · August 17, 2006, 08:58:23 PM

Heh this is thing is almost a textbook example of the most common opamp usage in electronic circuits

And could be used as an addition to the effects that don't have output level control.

I apologize!

The Vb is half the voltage reference point (4,5V)

KerryF · August 17, 2006, 09:01:51 PM

Wow i am really stupid.. I think its time for me to sleep

. I put Rb instead of Vb. Ok, so you are saying its just for reference, and they just connect with eachother? Thanks man.

QSQCaito · August 17, 2006, 09:05:45 PM

Quote from: call1800ksmyazz on August 17, 2006, 08:54:46 PM

Updated. Sorry. Im a noob with op amps....

And this isnt the exact schematic you used. Your layout is a bit different. And also, do the "Rb"s just go together? Or what do they do?

I think you made a mistake, this is the same than the other one, 9v+ goes to pin8, to legs 5 and 3 you should add Voltage reference(if im not wtong), and i think the output reference is missing out from c2

bye bye!

Branimir · August 17, 2006, 09:07:15 PM

Quote from: call1800ksmyazz on August 17, 2006, 09:01:51 PM
Wow i am really stupid.. I think its time for me to sleep . I put Rb instead of Vb. Ok, so you are saying its just for reference, and they just connect with eachother? Thanks man.

My english is bad, so does the reference sentence too

You need that part of the circuit too. Those two Vb points on the first schem connect with the Vb on the second one (my post before this one).

And that's about it.

KerryF · August 17, 2006, 09:14:00 PM

QSQ- Look again, its fixed...

Branimir- Thanks for being patient. Its still a little hard to understand what your saying, but just to clairify, I am to connect the two "Vb"s from the layout i put and connect them to the "Vb" on the other schematic piece? Is that what I do? Is that needed, or can I just connect the two from my layout?

Branimir · August 17, 2006, 09:17:15 PM

All three Vb's connected together

KerryF · August 17, 2006, 09:19:01 PM

Yay! I got it. Thanks so much! I learned something today.

Ok finally... If you check the other layouts up on this page, you can see its the final version completed. Is it right yet?

KerryF · August 18, 2006, 08:51:47 PM

Anyone test or varify yet?

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