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Thursday, April 22, 2010

Good Vibrations!

Somehow this goofy circuit diagram (sent to me by Mike, KC7IT) seems appropriate this morning. That is because, gentlemen, this diagram represents the kind of homebrewer I've been this week. After far too much struggle, and with the kind assistance of wizards from around the globe, I succeeded this morning in making an astable multi-vibrator do its thing. Not exactly a momentous achievement, I know. What you may ask, was the problem? Simple: Hans Summer's diagram called for 680K resistors from the power supply to base. But I somehow managed to put in two 68K resistors. This apparently results in an entirely different RC time constant!

Anyway, it is now percolating along nicely. The 2N2222s work fine, as do the two 10 uF electrolytics in parallel. It seems to produce a frequency of around one cycle every 15 seconds. That should be just about right for the QRSS FSK.

Thanks to all for the help and assistance provided. And thanks to xkcd for the cartoon!

5 comments:

  1. That's the most recent xkcd comic - great stuff http://xkcd.com/730/

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  2. Glad you liked it, Bill! See what's connected to the antenna? A mixer, naturally. 73 de KC7IT

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  3. I like the resistor that reads "120 ohms or to taste" and the "moral rectifier". When you've a chance pse chk email WSPR questions...

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  4. Congrats on getting it working!

    About xkcd comics... if you go to the xkcd site make sure to hover your mouse over the picture for a moment. There's always a second punchline in the tooltip that pops up.

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  5. This is great, provided a much needed laugh. I like the flux capacitor.

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