Mood:
caffeinatedNow Playing: Black Metal Radio - Episode 144
Topic: Switchers & Buffers
How's everyone doing out there? I haven't done an update in two months... sorry about that, I guess I'd been waiting to have something interesting to put up.
Here's an interesting little box I built for my friend Alex:
Nice, aye? It's not the cleanest work I've done, but I am pleased with how the finish came out toughness-wise. The gloss coat is Rustoleum laquer that I "baked" with a heat gun. I'm pretty much hooked on the heat gun technique now, and I'm not going to poison my oven any more by baking boxes in it. Heat gun all the way! It's so much easier to do with less guess work (you can watch it all happening as you work on it) and the fumes don't concentrate in one area like when you use an oven, and it would be easy to set up a fan for some ventalation.
But what about the inside? The circuit itself is pretty simple; a basic non-inverting buffer feeds two output buffers that have polarity reversing switches that allow them to be either inverting or noninverting amplifiers. The polarity switching circuit is a basic thing found in The Art of Electronics. The whole pedal is just some textbook circuits being powered by a application note MAX1044 power circuit.
The MAX1044 is used as a negative voltage generator to give the opamp a true bipolar supply. In the majority of cases, I always try to run an opamp from a bipolar supply whenever possible. It allows the cleanest sound with the widest dynamic range. In the case of this circuit, it can take an input level of about 8 volts before it will clip.
Here's a couple pics of the board:
I did the usual perfboard thing that I'm known to do. I mounted the switches directly to the board so it would be easier to mount it in the box. I probably agonized for an hour about how the hell I was going to mount it and still have room for the battery. Then finally, I realized it would be really easy to mount the switches to the board and build it up around them. It made a couple things about the layout a little weird, but whatever, with perfboard it's very easy to work with all three dimensions in a way that's almost impossible with PC boards.
What's with the missing socket contacts? Those were removed to make it easier for wires to pass on the wiring side of the board in a couple trouble spots. The are pins that aren't used.
Here's a couple more pics of the wiring of the footswitches and LEDs and then finally, everything together.
