# Voltage level shifter

Discussion in 'General Electronics' started by [email protected], Jul 23, 2003.

1. ### Guest

Hi,

I'm trying to convert some 0 to 5V signals into -5 to 20V signals.
Is this possible using a level shifter of some sort?

Thanks,
Sung Hon

2. ### Robert BaerGuest

Signal in: TTL spec of 0.8V max low and 2.0V minimum high?
Assuming signal out spec of -5V low and +20V high?
This requires voltage gain as well as shifting.
Input stage, mainly for level shifting: Input signal to base of PNP,
emitter biased at 1.4V and collector to -5V supply via a resistor R1.
Second stage, for gain and re-inverting logic: collector drives base
of NPN thru R2, emitter of NPN to -5V and collector goes to +20V via R3;
output at NPN collector.
This is one crude way of solving that.

3. ### JeffMGuest

I'm trying to convert some 0 to 5V signals into -5 to 20V signals.
Easiest way:
1) A non-inverting op amp
2) with a gain of 5
3) and a pot to give a -5V offset

These are fundamental concepts
covered in any text which discusses op amps,
probably available in your local library.
The National Semiconductor Linear book is worth having for this kind of thing.