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Unread 18-06-2012, 21:56
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Ether Ether is offline
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EE question: convert RS232 voltages to RC servo


Looking for EE's to comment please.

I want to convert a -12V to +12V PWM signal to RC servo voltage levels (0 to +5V), with sufficient current to reliably drive a Victor.

I cannot locate any specs for the Victor's input impedance and required minimum input voltage.

I'm thinking a simple circuit like this will do the job. The questions I have are these:

- Is 1200 ohm a small enough output impedance to reliably drive the Victor's input?

- Is the 2.7MegOhm small enough to allow the 12V input to drive the 2N3904's base?

- Will the transistor operate as desired (i.e. shut off) with a -12V signal at the base, without damaging the transistor?

- Will these resistance and voltage values keep the 2N3904 within a safe operating range ?



Last edited by Ether : 18-06-2012 at 22:04.