side tone circuit

[M0JHA]

Hello, im trying to make a side tone circuit for my pixie. I have found one that seems to be used with the pixie but cant seem to get it to work only hearing a click on keydown.

Anyway i have found another sidetone circuit below using  NE567. I can't find this listed in any of the places i normally get components so i want to know if anyone knows an alternative to this chip?

I dont know which country this design is from so im not sure if the number of the chip will change throughout different countries.

http://www.qrp4u.de/docs/en/sidetone/index.htm

billy uk

[KE7AXC]

Digi-Key has three versions of a National Semiconductor LMC567 that is probably the same or similar.

[M0JHA]

ok thanks for that i have now found some ..

cheers billy.

[WB6BYU]

Actually the CMOS version (LMC567) may work differently:  I'm going
from memory, but I think the oscillator in the CMOS version runs at
twice the decode frequency, which may or may not be an issue in that
circuit.

I'd use a 555 timer instead - they are cheap and ubiquitous.