Build Your Own Clone Message Board

I think we've established it's a TL081 or other standard single op amp (- input pin 2, + input pin 3, output pin 6, power pins 4 and 7).

The power supply R5, R6, C7, C8 doesn't look right, +ve should run directly to pin 7 with R6/C7 parallel to ground and -ve should run directly to pin 4 with R5/C8 parallel to ground. You've got a trace that runs: +9V, bottom of R6, bottom of R5,
left side of C8, neg. Battery life - 2 seconds !!!

Lug 3 of the bass pot should run to the junction of R8/C2 and not R8/C5

Good call on the Bass Lug 3. And you are definitely right about the R5, R6, C7, C8 situation. I got a layout (very similar to Hogan's) about 75% done, but I am too tired to finish tonite. Hopefully over the weekend, if I am not too busy.

_________________

With the noted fixes .

_________________

Any takers ?

Sure, How much? I'd take 4. ~MJH

_________________

Oh man, is it ready to be etched?

_________________

Etching tonight. Will keep you guys posted. Hopefully built by Monday.

_________________

_________________

top shelf! I'm stoked.

_________________

Just what I've been looking for. If someone adds a mid range control I'd be set. Does this cut freqs too?

-6db to +12 db on both treble and bass.

_________________

Board etched and drilled. Population ...Sunday night.

_________________

Awesome! Can't wait to hear the verdict

_________________

Anybody doing this project is going to want to use a 10K-25K audio pot as a volume. out from board to lug3, lug 2 to tip of output jack and lug 1 to ground.

_________________

Well? Don't keep us in suspence.

_________________

Update.
I etched both boards (hogan and tonmann) and populated both last night. Did not get a chance to wire them up, probably Tuesday. I was just too tired last night. I am in the process of moving my family and my mom simultaneously.

_________________

OK, I am an idiot. I populated tonmann's PCB even though I didn't flip the PCB transfer image. I wasn't thinking the IC chip pins would be backwards. So board is useless. In DIY, which I use, you do have to flip image to transfer. You live you learn.
I will flip and get in done in few days.

Hogan's board is wired and doesn't work. I am getting nothing. I will try and probe it tomorrow. Too tired now.

I'm working on it guys.

_________________

My pcb is already flipped,

I don't belive this is meant to be used as a stand alone circuit i.e. it should be inserted in the signal chain as a tone control.

I'd be willing to do a stand alone version + pcb layout if there are any requests.

That's what I'm interested in
I just don't understand why this shouldn't work on it's own (I still know nothing about electronics).

_________________

_________________

The problem as I see it is that guitar pick-ups and pots should sit at ground potential (battery negative). With a single battery we need a bias supply (already there at point G). The input (point A) needs to be biased via a resistor and preferable a.c. coupled from the guitar. The grounding for the output (point C) needs to be battery negative.

Happy to hear any comments

_________________

Not according to my book. It can run on either 1 or two batteries w/o any additional circuitry. I'll try to scan in the whole chapter this weekend

~MJH

_________________

Hypothetical question, run with me here. Suppose you added a BMP style tone control before signal hits the individual freq controls, would this act sort of like a sweep? Could you control te frequencies in the range you've selected? Just pondering some things.