brainwagon "There is much pleasure in useless knowledge." — Bertrand Russell

31Mar/110

555 Astable Multivibrator as an AM Transmitter

I mostly avoided the siren song of the 555 timer that seemed to echo through the blogiverse during the recent 555 contest, but when I was out and about last weekend, I picked up 10 of them from Anchor Electronics, and they have been taunting me from the shelf ever since. So, last night I dug out some resistors and caps, and tossed together a simple multivibrator circuit. Today, I was pondering what I could do with it, and I recalled seeing the circuit being used as an AM transmitter. The basic idea is to simply AC couple the audio onto pin 5, and voila. So... that's what I did!

I'm actually not quite sure I completely understand how this works (it's not entirely clear to me whether it is more accurate to call this pulse width modulation or frequency modulation) but the circuit does work. I imagine that once I understand it better, I'll be able to make it work significantly better. But that's something for the future.

31Mar/111

Amazing small machining site…

Back when I was into building telescopes (something I haven't done very much of in the last few years) I developed a desire to try some machining. I managed to pick up a 6" Atlas mini lathe. And... well.. I've done very little. It's sitting on my workbench in the garage. This website demonstrates some cool projects that can be done with inexpensive Taig mills and lathes.

So, I got a Taig.

Filed under: Amateur Radio 1 Comment