Hi,
I hope you can help me with it 
I want to connect one power supply to power a Teensy 3.0 (5v dc) and a synth expander (1 is 12v dc and 1 12v ac)
So I need to transform
- 12v dc to 5v dc
- 12v ac to 5v dc
How can I archive this?
Thanks!
12v dc to 5v dc: 5V Regulator like the 7805
12v ac to 5v dc: bridge rectifier, large capacitor, and 5V Regulator like the 7805
Thanks, but I heard that the 7805 would get to hot for 12v to 5v regulation. 
12v dc to 5v dc: I think You should use LM2596 step down buck converter from ebay.com
Full assembled circuit cost about 2$.
12v ac to 5v dc: bridge rectifier, large capacitor, and ~~5V ~~ (sry, didn't deleted) LM2596 step down buck converter.
flocked:
Thanks, but I heard that the 7805 would get to hot for 12v to 5v regulation.
Depends on how much current you are drawing.
Thanks I think I will use the OKI-78SR-5/1.5-W36H-C. Mutable Instruments uses it for 12v to 5v regulation with 1.5a.
Could maybe anyone take a look if my schematic makes sense? Thanks!
It's for 12v dc to 5vdc?
It is ok. Just add 470 mfd to 1000 mfd ( 25V) cap in the input of voltage regulator.
Well the capacitor is the right idea but they are way bigger than you need. I would suggest 1uF on the input and 47uF on the output. And throw in a 0.1uF ceramic for good measure across each of them for the high frequency noise.
At the input side is ok but there is no need to put high value cap on 5V output side. Just have one 0.1 mfd disc cap.( to take care of noise) on both side ( as rightly suggested by Grumpy_Mike) and may be small cap of around 22 mfd or 47 mfd on output will do.