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 Theremax supply with USB possible? 
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Joined: Fri Apr 12, 2013 10:59 am
Posts: 2
Post Theremax supply with USB possible?
Hi,

I would like to use my computer USB port to supply the theremax. I know that USB is 5V / 500ma. Would it be possible with a voltage booster to get 12V, but i don't know how much current the theremax draw?

Thanks


Fri Apr 12, 2013 11:22 am
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Joined: Sun Nov 09, 2008 2:49 pm
Posts: 726
Post Re: Theremax supply with USB possible?
Theremax has on-board regulation of the usual 12V/100mA linear DC wall-mounted power supply to 8.2V by a 100ohm resistor into an 8.2V zener diode. 20mA of current flows at this 8.2V, V+ supply. Maybe a usb chargeable 12v battery pack would be a simple solution?

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Fri Apr 12, 2013 11:36 am
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Joined: Fri Apr 12, 2013 10:59 am
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Post Re: Theremax supply with USB possible?
Thanks for the information, how about using something like this:
http://www.ebay.com/itm/5v-12v-Step-up- ... 4172437f0e

Output voltage: 11.7V
Output Current: 60mA

Maybe adjusting the 100ohm resistor?


Fri Apr 12, 2013 1:29 pm
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Post Re: Theremax supply with USB possible?
That looks sufficient for the power, but it might radiate/contain energy that will appear as a tone in the theremin output. Shielding of the circuit and locating it away from Theremax will help to minimize this possibility, as will the initial tuning of oscillator one as set by L1's slug adjustment.

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Sat Apr 13, 2013 10:51 am
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