Frequency multiplier circuit ?

Hi

I have a ttl signal that is a tach signal that goes from 0 to 2 kHz.

I need to multiple the tach signal frequency by two ( X2 ) from 0 to max speed which is 2kHz.

Is there a simple way to do this? I think I remember seeing a XOR gate configuration that accomplished this?

Any ideas?

Thanks

If the signal comes from a pickup coil so that it has positive an negative transitions:

Two NPN transistor, Q1 and Q2, collectors tied together and pulled up to V+ thru a resistor.

Emitter of Q1 tied to ground, base of Q2 tied to ground.

Base of Q1 tied to emitter of Q2, from this common point connect a resistor to your pickup coil.

Values to be calculated by the student ;-)

This configuration was used in speed-related smog controls (deceleration throttle stop) in the mid 60's.

...Jim Thompson

Yes. I would say use a shmidtt trigger inverter to clean up the input signal, feed through an RC delay, into another shmidtt inverter, and xor the outputs of the two inverters. Invert the output again if needed.