The easiest thing would be to get a 15V power supply, then add 9V & 5V voltage regulators. The [u]78xx[/u] series of voltage regulators are popular and easy to use (requiring only 2 capacitors).
Do you know the current requirements? The power supply you buy needs to be rated for at-least the sum of the currents. And although the voltage regulators can "theoretically" handle about 1 Amp, linear regulators like this are best if you keep the current below a few-hundred milliamps, especially if you are "dropping" a lot of voltage across the regulator... Power (related to heat) is calculated as Voltage x Current, and in this case it's the voltage across the regulator.
If you want to build one from scratch [u]here is a basic power supply schematic[/u]. (You don't need the "bleeder resistor".) The capacitor should be 1000uF or more, and it should be rated for 25 V or more to give yourself some safety margin. Of course, in this case you'll need 3 voltage regulators.
Note that the peak voltage out of a transformer is about 1.4 x the RMS voltage, and the capacitors will charge-up the peak. So, a 12VAC transformer can give you more than 15V. Plus transformers are rated for full-load and the voltage will be higher with no load or a light load (little or no current).
here are the required voltage values of the three devices:
TC Voice-Live Helicon: 12 V, 0.4A (i thought it were 15v as written in my last post, sorry)
Midi-Controller-Board (DIY, Arduino-based): i think 9V, 0.5mA should be ok?
Line 6 M5 Stompbox: 9V, 0.5A
@DVDdoug: Can i use my TC Helicon 12V power supply device as input for my circuit and generate the two 9V power supplies with the voltage regulators?
I have a L7815 and a L7915 Voltage Regulator.
Do you have a link to a circuit for me or can you describe me, how i have to built up the circuit to get
12V 0.4A and two 9V 0.5A supplies at the end?
Sorry, as said, i can solder, but i'm not experienced in building up circuits ;-(
I wouldn't go the linear regulator method... for this.
Using a 78xx to provide 9VDC from a 12V source @ 0.5A you are generating 1.5 watts of heat on the poor linear regulator. Or even worse 9V at 0.5 + 0.5A = 1 AMP generating 3 watts of heat from the drop out from 12V.
You also need to consider the current rating on your 12V supply. Does it have enough?
You may need a separate power supply for your 9V devices with the correct power rating to supply enough for everything you will be using. A shortage of supply current may not be immediately apparent but may affect the performance of your devices. For audio it can cause unwanted distortion to strange phase issues and unintentional compression. For your digital devices it can cause resets and other strange behavior.
In order to reduce the heat, instead of linear regulators I suggest you user buck converters to get the voltages you need.
As a source use a laptop power supply, most will produce about 18V at enough amps.
Then get a adjustable buck converter from ebay, maybe this one https://www.ebay.com/itm/173898668361
They are very cheap and you can get one for each pedal.
The trade between a buck converter and a linear regulator is heat vs. electrical noise and most cheap buck converters from ebay wont have good filters. But they are so cheap that probably you can afford to do some tests.
