On Oct 30, 1:40*pm, "dave.harper" wrote:
I'm using the wein bridge to generate audio tones that are fed to the
transmitter for digital radio communication (basically a homebrew ASK
radio modem). *I'd be open to using that, but I'm not aware of any
radio modems that output square waves.

This oscillator also has 2 digital pots attached: 1 to trim the space
tone, and 1 to trim the mark tone. *There's a high speed switch
between the two pots to rapidly switch between mark and space tones.
I could use this same setup with a 555 and trim the resistor to vary
the pulse duration, but I'm not sure what impact a square wave would
have on transmission, reception, decoding, etc...?

Has anyone heard of a square wave being used as an audio tone for
digital radio communication?

Thanks in advance,
Dave

On Oct 30, 12:06*pm, George Herold wrote:



Hmm I have no idea if that will make any difference. *What are you
using to control the feedback? *Can you use a more robust oscillator
(as John suggested) Some type of 'bang-bang' rather than sitting on
the 'knife-edge' of oscillation with the Wein bridge. *I needed the
low harmonic distortion of the Wein bridge... Is that what you need?

George H.- Hide quoted text -

- Show quoted text -

Hi Dave, I know nothing about ASK radio modem.
I think you can get a triangle wave out of a 555 (Or some other charge/
discharge osc.) You can then low pass filter the triangle to get rid
of the sharp peaks.. There are also some trianlge wave to sine wave
converter circuits that use diodes or transistors to 'smooth' the
tiangle wave. If you don't care too much about harmonic content then
either approach may work.

George H.