How does the power work on this circuit?

[tbassist4]

So, how does the power work on this bad boy? I see three +5's and one -12...

[JimmyM]

three +5's and one -12? that equals +3. that's how it works.



sorry...just a little loopy from too much diet cola.

[NateS]

ah, the diy bitcruncher thread has reared itself, haha.

i see no -12 at all. It runs on 5vdc, so you'd have to implement a way to lower the 9volts to 5. I don't understand how, maybe Taylor Livingston can step in and help?

[bongomania]

The -12 connects to pins 3 and 16 of the DAC. To get +5 is easy: just take a normal 9V supply and use a simple voltage divider circuit to shunt 4V across a resistor, dropping the remainder to 5. Getting -12 is not quite as easy--you have to either start with 12V or higher, or use a voltage-doubler circuit like a "charge pump" to boost 9V up to 12. Then you have to take the ground line of the +5V and treat that as the "positive" leg of the 12V circuit, with the 12 then appearing to be -12 as far as the circuit is concerned.

[NateS]

oh, noooow i see -12...

[Munjibunga]

Originally Posted by bongomania

The -12 connects to pins 3 and 16 of the DAC. To get +5 is easy: just take a normal 9V supply and use a simple voltage divider circuit to shunt 4V across a resistor, dropping the remainder to 5. Getting -12 is not quite as easy--you have to either start with 12V or higher, or use a voltage-doubler circuit like a "charge pump" to boost 9V up to 12. Then you have to take the ground line of the +5V and treat that as the "positive" leg of the 12V circuit, with the 12 then appearing to be -12 as far as the circuit is concerned.

Why not use a 12-volt PS, and divide down to the 5?

[Taylor Livingston]

Bongo pretty much nailed iton the +5v, although I'd personally use a regulator for that.

I must be misreading your bit about -12v, because as it reads to me it doesn't seem right. Are you saying he should plug +12v into the V_ee pin instead of -12v? It sounds like you're talking about making 2 different circuits, one of which is positive ground, but AFAICT that wouldn't apply here. Am I crazy or just misunderstanding you?

In order to get -12v out of +9v, you need to not just double it up but invert it, then drop it down with a voltage divider, zener, or regulator. Look to the almighty LT1054, it does what you seek! Or actually you might be able to get by with the MAX1044.

Originally Posted by Munjibunga

Why not use a 12-volt PS, and divide down to the 5?

Just because these days most people want to power all their stuff on a 9v daisy chain. Makes powering your pedals simpler.

[bongomania]

I'm probably not quite correct on the 12V dealio. My thought was that -12 is achieved by treating the ground of the +5 power lines as the "zero" reference.

[PhiDeck]

OP: Suggest you determine and consider the circuit design credentials, if any, of those whose advice you may be considering following. Those are relatively inexpensive ADC and DAC, but there's no sense in burning money.

[Taylor Livingston]

Originally Posted by PhiDeck

OP: Suggest you determine and consider the circuit design credentials, if any, of those whose advice you may be considering following. Those are relatively inexpensive ADC and DAC, but there's no sense in burning money.

Ouch, says the person who posted that pic a while back. I didn't design it or ever build it. If it's unclear, the point of that circuit is not to build a nice A/D/A for recording or something, but to build a nasty bit crusher effect.

Now, with that said, that circuit still isn't the best way to go to make a bit crusher, and I'm not even sure the switches would work as drawn, but most DIYers are turned off by the prospect of writing code and doing proper DSP, so messing with those chips on a breadboard is the only way to get a real bit crusher (not a sample rate reducer) without writing code.

What would you suggest instead?

[boomertech]

Originally Posted by JimmyM

three +5's and one -12? that equals +3. that's how it works.



sorry...just a little loopy from too much diet cola.

Great idea! Lets look at +5 and -12 as a difference of 17V.

Originally Posted by bongomania

I'm probably not quite correct on the 12V dealio. My thought was that -12 is achieved by treating the ground of the +5 power lines as the "zero" reference.

Let's take Jimmy's idea of adding the voltages (with slightly different math) and combine it with Bongo's "zero" reference and voltage divider. Bias and zero references have been used in countless pedal designs and I don't see where this circuit would be any different.

You MUST use an isolated 18V supply for this to work properly!!!

-Frank

[Silent Fly]

Alternatively...

[Taylor Livingston]

That's pretty clever, sfx! I have never seen something like that in effects or modular synth building. I simmed it and it looks like it works pretty well. Cool design.

[PhiDeck]

Originally Posted by Taylor Livingston

Ouch, says the person who posted that pic a while back. I didn't design it or ever build it. If it's unclear, the point of that circuit is not to build a nice A/D/A for recording or something, but to build a nasty bit crusher effect.

Now, with that said, that circuit still isn't the best way to go to make a bit crusher, and I'm not even sure the switches would work as drawn, but most DIYers are turned off by the prospect of writing code and doing proper DSP, so messing with those chips on a breadboard is the only way to get a real bit crusher (not a sample rate reducer) without writing code.

What would you suggest instead?

Actually, I wasn't referring to the circuit itself, but rather to the suggestions (until then) for how to power it.

The "burning money" part pertained to the likelihood of smoking parts if the power supply was inadequately regulated, not to the bill of materials cost being too high.

[JimmyM]

Originally Posted by boomertech

Great idea! Lets look at +5 and -12 as a difference of 17V.

lol! well i know nothing about what i just did, but glad i could help. very interesting discussion, though...i can almost make heads and tails out of it.

[Silent Fly]

Originally Posted by Taylor Livingston

That's pretty clever, sfx! I have never seen something like that in effects or modular synth building. I simmed it and it looks like it works pretty well. Cool design.

Thanks Conical. It is just a starting point but it should work.

I am not sure I invented anything new though. Have a look to "The Art Of Electronics, 2nd ed" page 621

[bongomania]

Originally Posted by PhiDeck

Actually, I wasn't referring to the circuit itself, but rather to the suggestions (until then) for how to power it.

The "burning money" part pertained to the likelihood of smoking parts if the power supply was inadequately regulated, not to the bill of materials cost being too high.

It looks like the only post you could be referring to was mine. Yes? If so, please note that both suggestions I made are perfectly valid. The only problem is if the person taking my suggestions doesn't know how to do that properly (e.g. by not regulating or isolating the power).

[tbassist4]

Originally Posted by Silent Fly

Thanks Conical. It is just a starting point but it should work.

I am not sure I invented anything new though. Have a look to "The Art Of Electronics, 2nd ed" page 621

Soooo....I must ask, but if I wanted to go about building this thing, how would I do that exactly? I see a lot of parts with unmarked values (I also understand that this is your circuit and you may have purposely chosen to withhold some things, which is perfectly fine). In addition, I see two separate circuits, the obvious main one, and a little one in the upper left hand corner of the image.

I have another schem that Taylor Livingston posted that is a Pulse Wave Modulator, and based off of an idea that the OP had in that thread, I think it would be cool to put these two in one box with a switch so you could have an 8-bit video game stomp box.

Anyways, just some thoughts.

[Silent Fly]

Originally Posted by tbassist4

Soooo....I must ask, but if I wanted to go about building this thing, how would I do that exactly?

The schematics contains only the core part. It lacks of at least of 2 parts (as indicated in the schematics): an input stage that buffers the input and increase the signal level enough to trigger the comparator stages. It also need an output volume control. I would also add some post-processing filter and a tone control.

Originally Posted by tbassist4

I see a lot of parts with unmarked values (I also understand that this is your circuit and you may have purposely chosen to withhold some things, which is perfectly fine).

I didn't withhold any information. The missing values need to be calculated and tried. I don't have the time to do it but I may do it in the next few days. I suggest you don't hold your breath

Originally Posted by tbassist4

In addition, I see two separate circuits, the obvious main one, and a little one in the upper left hand corner of the image.

It is the same circuit. The two parts share a connection (V2). The part in the upper left corner (R5=R9=10k, C2=100uF) create a 4.5V voltage that is used by the rest of the circuit where indicated by the label V2. In other words, all the V2 points are connected together.

[A440Hz]

Another alternative on the power supply is to do something like what bongo said--create a voltage doubler (or, "increaser") circuit to get +12V w/r/t the common ground (i.e., 5V referenced to same ground), then use a transformer to flip the polarity w/r/t ground.

This means iron inside your box, which is weight and cost. But it wouldn't have to be giant. Not like an output or power transformer for an SVT.

I would definitely second the opinion about using regulators. A voltage divider on 9V could get you 5V, but not at a low impedance. A regulator would drive the voltage at low impedance.

Also, what are the specs of the A/D and D/A? How tolerant are they of decaying voltages like with batteries? Since this is supposed to be a bit-crusher (to PG-13 the common name for the genre, a "Mess Stuff Up" effect), maybe low voltages as the battery dies gives you a cool effect, or perhaps no workage at all. Some data sheet study would be a good investment.

Also, check out www.d16.pl : they have a VST effect called Decimort. Now you won't be able to use it live without something like a Muse Receptor ($2k!), but just check out some of the chiptune stuff they're doing.

Bitcrushing is part of it, but you can also really MSU (mess stuff up) by crossing lines between the A/D and D/A (perhaps mode-switchable) and by violating sample rate rules (Nyquist criterion-- highest frequency into the A/D should be half the sample rate; if you violate that, you'll get aliasing, and here, that's good). Plenty of the old 8-bit sound generators had aliasing problems: Commodore 64, NES, etc.

I'm very interested to see how this progresses. I'd probably just buy a Line6 Tone Core Developer's kit and do it in DSP, but that's me. Code is usually preferable to a soldering iron, though I do love the smell of smoking rosin, too.