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Dot Matrix Printer

Ever consider driving a dot matrix printer with logic circuits? I'd like to build a train detector to count trains passing my house. I suspect that train traffic is up recently. Anyway, the detector would listen for the train horns and then every minute print some character if a train was detected. I'd try for 120 characters per line so I could track two hours on each line. Or maybe report each half minute. Anyway, the detector uses a tone detector tuned into the train horn frequency (don't expect too much trouble with doppler, trains are usually slow in passing my area). That will bring the 'train' signal high. Every minute a clock pulse checks the signal and the proper character is presented to the printer interface and strobes the 'data ready' signal to the printer. After 120 minutes (think cascaded counters here) out goes a CR followed by LF.

Perhaps you could build a temperature recorder this way. I wonder if there is any way to add a real time clock to the device without adding a microprocessor.

Hmm, http://www.maxim-ic.com/appnotes.cfm/appnote_number/965

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7050 days of detection
mod: 12/3/08, 5:42 AM

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Biography

Randall Bohn lives in Orem, Utah, USA. He works as a Software Quality Engineer. He is a big fan of the AVR line of microcontrollers. He has been in the computer industry since 1989. Randall is married and has three children.

rsbohn can be reached via gmail.com.


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