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Author Topic: Convert/increase voltage output on Arduino  (Read 807 times)
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I'm attempting to build an digital/analog hybrid synth using my arduino uno and I'm stumped on a power supply problem. Currently, I'm working on one of the VCOs, but it requires +15 volts DC, -15 volts DC, and a ground (the schematics for the VCO are here http://www.birthofasynth.com/Thomas_Henry/Pages/VCO-1.html). What is the best way to use to arduino outputs to power the VCO?

 I was thinking about using a NKA0515DC (http://www.mouser.com/ds/2/281/kdc_nka-45878.pdf),which converts 5 volts into +/-15 volts. I'm still a little shady on how to use it though, and I'd have to use the ground on the arduino, if that's even possible. The other option I have run across is the TLE2426 (http://www.mouser.com/ds/2/405/slos098d-121616.pdf), witch has a lot more documentation and output a positive and negative voltage, in additon to having a virtual ground. The problem is that it only output +/- half of the voltage in. This means that I would need to supply 30 volts, either from an external source, or perhaps by boosting the output of the arduino somehow, or even combining 6 IO ports set to HIGH (5v * 6 = 30v, right?)

Anyway, what is the best method for supplying power? Should I try one of these, or is there another more efficient method? Thanks in advance.
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I was thinking about using a NKA0515DC (http://www.mouser.com/ds/2/281/kdc_nka-45878.pdf),which converts 5 volts into +/-15 volts. I'm still a little shady on how to use it though, and I'd have to use the ground on the arduino, if that's even possible.

I think you hook 0V and Vin- to Arduino Ground, Vin+ to +5V.  Then use Vout+,0V,Vout- for your split supply.
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Thanks for that tip John.

I forgot to mention in the original post, the final product will not be a modular synth, it will be an "all in one" (VCO, VCA, filter, ect.). The arduino is going to handle MIDI data and turn that into a CV. I figured the easiest way to supply power would just be to use the arduino.
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It seems to me,  that device is going to require more power than an arduino can deliver.

Arduinos are not designed to run devices with high power requirements,   thats why you
need some other kind of supply to run motors or servos or anything.

I read through that Thomas Henry thing and it wasn't very clear about power.

Devices that start with 5V  and generate higher voltages  are only usable for very
small amount of power.  You need to start with a higher voltage and work your way
down.

If you need a 30V range,  I'd look at something like this

http://www.ebay.com.au/itm/36V-10A-360W-DC-Regulated-Switching-Power-Supply-CNC-/280708842108?pt=AU_B_I_Electrical_Test_Equipment&hash=item415b8d027c

and then work on your intermediate voltages from there.    You'd also need to consider how the whole
device is going to be grounded.
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It seems to me,  that device is going to require more power than an arduino can deliver.

The datasheet says that the NKA0515DC draws 253 mA at rated load.  That's well within the spare capacity  of the Arduino 5V supply (about 400 mA on USB, about 900 mA on external DC).
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If it is, you can use a transistor or MOSFET.
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Even if you power the synth with 30V you will still have problems controlling it with 0-5V from an arduino. Anyway, I was thinking, why use such a high supply, as far as I can tell the synth could be made on a much lower supply, even 5V, probably. It's mostly the TL072's opamps that should be replaced with something that works with lower power. The 3080, whatever that is, seems to work at 5V, and the transistors would need some lower resistors. Of course, I am not sure how much "black magic" goes into VCOs, but it would be an interesting project.
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