Hi,
I have never really fiddled with audio signals and have the need to generate morse coded audio signals into an aircraft intercom system. I have prototyped a circuit which uses 555 timers to generate an appropriate frequency (say 1020 Hz). I use a microcontroller to modulate the audio tone to generate the morse code output. Looking at the specs for some of the nav radios that normally attach to the intercom system, I have the output isolated from my circuit by a 600 to 600 ohm audio transformer. After testing, I am seeing the my square wave outputs are distorted (from the 555) when connected to the transformers. Where to go next? I built a test box with a 150 ohm speaker, which I connected directlyt to the output of the transformer. The output tones seem might distorted. Cheap speaker (yes)? Overdriving? Helpful links or suggestions? Thanks for looking at my post.