Analogguru - Split Supply from 9V

analogguru · Post by **analogguru** » 02 Jul 2007, 21:04

Here is an untested schematic for approx +/- 15 V from a 9V battery:

"Split Supply from 9V" schematic

Don´t show or sell it to Zacki or his Boutique-cloner friends

analogguru

soulsonic · Post by **soulsonic** » 02 Jul 2007, 21:30

That looks really neat - I'll have to try it, I've got a couple 555s hanging about. Just to be sure - the negative terminal of the battery is floating above earth? Looks like I'll need a switch to turn it on and off instead of the input jack trick.

analogguru · Post by **analogguru** » 02 Jul 2007, 21:52

Battery minus IS ground, you can use the normal jack setup.

analogguru

soulsonic · Post by **soulsonic** » 02 Jul 2007, 22:12

Oh yes, now I see it... Brilliant design Mr. Divos!

analogguru · Post by **analogguru** » 02 Jul 2007, 22:22

It´s more than 50 years old and was used in every televisor, you can say thanks to:

Mr. Villard

Sorry, unfortunately I uploaded the wrong file missing one diode, please download again.

analogguru

soulsonic · Post by **soulsonic** » 02 Jul 2007, 22:33

Ha, ha! Yes, that's the one! I just never thought about doing it with a 555. I like Jochen's page alot, I've spent alot of time on there reading about high voltage - there was a time when I was wanting to do some experiments with ions.... well, that might still happen, I just need to find the time to set the thing up and see... first I need some 10kV diodes.

Post by **modman** » 05 Sep 2007, 20:19

Am I right in thinking that, apart from the cheaper chip, this config is better armed against voltage higher than 10V then the max1044? Killed two of them some months ago. A friend killed another with an unregulated supply.

and it really deserved a bump, this one
I mean, has it been tested yet?

RLBJR65 · Post by **RLBJR65** » 06 Sep 2007, 01:21

I'm almost done putting it together. Couple days until I can get back to it though.
Did this layout (obviously untested)
https://img213.imageshack.us/img213/1772/avgmka1.gif
For some reason I can't get the pic to size right in ImageShack

I can Email the original if someone wants to try it.

Post by **modman** » 06 Sep 2007, 07:30

Richard,

Great work! I think Photobucket has a size limit, if the file is too big, photobucket resizes it.

What are the pcb dimensions? Looking into a solution for decent hosting of the images. Imageshack doesn't have the restriction, but no gallery features either.

Will try this when I get round to fixing my PT80

marshmellow · Post by **marshmellow** » 06 Sep 2007, 10:45

Great! How much current can you draw from that? Is there a limit from this circuit or only from the power supply you use?

RLBJR65 · Post by **RLBJR65** » 06 Sep 2007, 12:01

Full size http://www.aronnelson.com/gallery/v/Ric ... M.gif.html

Modman it's roughly 1 3/8" X 1 1/4".
I hate making boards so almost all of my prototype work is done on perf first. On perf it's 14 holes wide plus a bit for screw heads say 16 wide and 12 deep.

Printing the transfer out at 49 to 50% of the original size should work.

It's a tight squeeze, watch you cap sizes C1 C6 C7 are especially tight.
1N4148 fit flat so if you use rectifiers like 1N400* they will have to stand.
I think I may space things out a bit if the circuit works okay.

vanessa · Post by **vanessa** » 06 Sep 2007, 14:20

Using a transformer for wall AC would it be easier to have a step down for 9V and use one of these [charge pumps] or step down to 15V and use a voltage divider?
I see that you can get a +/- voltage so that looks like a plus already. I'm thinking it might be cool to use in a pedal power box (like Steve's project at small bear) but wonder if there's a better way to do it?

analogguru · Post by **analogguru** » 06 Sep 2007, 15:09

I am all the time wondering, why people need such converters.
No one can tell me that it makes sense to use batteries for lets say 10 or more effect units.. this would make 10 or more batteries.

With these (battery powered) effect units you deliver a signal to an AC-powered (tube-amp). It doesn´t make sense (except of hum-reasons) to use batteries if there is AC available. For the price of two or three batteries you can afford an AC-adapter.

So if somebody is using an AC-adapter it doesn´t matter (to the adapter) if it should deliver 9V or 18V DC. Most of the effect units can be run on 18V by changing some capacitors, maybe one diode.

Then we have the argument of the battery-price. It is stupid to believe that you can save money by that. A MAX-1044 or similar stuff is not a perpetuum mobile. It will current for itself to work. Then you have the loss in the diodes which is transformed to heat. So to transform 9V to 18V you will never reach more efficiency than 90% - and the conversion takes double current out of the battery. Thus the battery life is only maximum the half.

And then is the question if you really need +/-9V or 18V like in the Klon. Sorry, if you look at the schematic (when this is true) the you will see that the input stage and the distortion stage are run only with 9V. The signal at the diodes will under no circumstances exceed +/-0,3V. After the Diodes the signal is amplified by a factor of 330k/47k = so the max. output swing would be +/-2,1V which can be achieved with 9V too.

Then we have the tone-control which acts only at high frequencies. If you use more than +6db treble boost you must have "special ears" or a special playimng style. +6dB would mean an output swing of +/-4,2 V which still can be delivered by 9V supply.

Now lets have a look at the "clean" signal path. A rough view shows that the signal is attenuated at least with 12db - that is 1/4. The maximum gain which can be achieved after the volume control is about 24 divided through 4 = 6. Now lets take a really high guitar signal with +/-0,2V and amplify it by 6 gives +/-1,2V now the tone control at +6db will result in +/-2,4V - which can be delivered from 9V.

Beside this: Did you ever feed a guitar amplifier with 18Vss ?

Did you ever disassemble a 9V-Battery ? Inside you will find 6 small cells of 1,5V, so where should be the differencew if you use 6 cells or 12 cells in series ?

So my conclusion (at least for for Op-Amp circuits):
Forget this f*cking voltage-doubling MAX-Mania. If you really need more output swing, use two batteries (The overall costs are the same) or use a 18V-adapter.

analogguru

Post by **modman** » 06 Sep 2007, 20:12

Maybe we should have a myth debunking thread about batteries. How many times I've heard the effect is more stable or sounds better with batteries

-- I'm still not buying that crap.

Still have to build the first pedal that doesn't perform clean with an DC Adaptor. The point is, I think, that most pedalboards are not equipped to have 18V ready, and you won't have to many effects that require them, so another sepearte adapter while only one was feeding my pedalboard?

Using maximizers with batteries is moronic, even I understand that.

My experience: put the volume on you small amp so low your guitar sound muddy, then kick in a minibooster at 9V and use volume to beef up. Clean? Ok, back up the volume on the booster again until it's just muddy with the booster on - then increase the voltage to 12V - does it clean up again? Or is it an illusion that this would have repercussions on my sound at normal settings?

soulsonic · Post by **soulsonic** » 06 Sep 2007, 20:20

Well put.

In defense of voltage wrangling circuits, I say that the best part about all these voltage converters is that they take up less space than a second battery. Using a MAX1044 to get a bipolar +/- 9v supply saves alot of space inside the box and it makes it easier to do the usual input jack power switch. And personally, I don't like to use AC adapters, the only time I use them is when something requires more current than is practical from a battery. I have no practical reason for this - it's just personal preference. I only use 1 pedal when I perform live, so batteries fulfill my needs just fine. If I used a huge pedal board with a dozen effects, then I would use an AC adapter, but using one with a single pedal seems like such a waste. And the cable from the adapter is never long enough, so you always have to use an extension cord..... I would most likely have the AC supply built into the pedal board and have a long mains cable.

AC power is good for when you're putting together an entire system that's designed from the beginning to be powered that way. Then, I think AC mains power is absolutely the best choice. But when I'm just making some boxes to play around with, I just go with batteries because it's much less of a hassle.

Post by **modman** » 06 Sep 2007, 20:41

hehe:
http://www.tonetoys.de/de/18_Volt_Booster-kabel.html

soulsonic · Post by **soulsonic** » 06 Sep 2007, 20:50

Why does it have an RCA plug on one end?
35 Euro for something like that? Maybe I should start making those to sell. I'll sell mine for 50 Euro so people will assume it's better!

analogguru · Post by **analogguru** » 06 Sep 2007, 22:19

35 Euro for something like that? Maybe I should start making those to sell. I'll sell mine for 50 Euro so people will assume it's better!

You could put in in a big case, write "Klon" or "820" on it and sell it for EUR 400,--

analogguru

Post by **modman** » 07 Sep 2007, 07:53

Gefundenes Fressen!

The RCA jack connects to the Big John, but you could just buy a Power Bitch.

soulsonic · Post by **soulsonic** » 07 Sep 2007, 18:22

Why don't I just come up with a generic supply and call it the "Voltage Cunt"? EUR 300. Offensive names make them work better and give me an excuse to charge double the price.