Phone Display on the Mend

Aug 22, 2015 by     Comments Off    Posted under: Roads & Rails Blog, Uncategorized

Phone Display- Back from the Dead!

 

Video link!: https://www.youtube.com/watch?v=FGlvfuZZ4AM

Visitors to our museum usually don’t come for anything but trains and Legos, but my Arduino Phone Dialing display did get some attention on Hackaday.com and YouTube, and it’s been frustrating to have to tell visitors that the darn thing hasn’t been working for over a year now.

I did a full rebuild with many improvements (display size, general ruggedness, better relays) but missed until yesterday the one real problem- we had AC power running a non-isolated relay for a DC circuit, and the bleed over was preventing the clicks from being counted properly. Arduino button pushes are not simple on/off voltage affairs, but are more like a radio signal: you provide a baseline low voltage, then a high voltage that the digital input recognizes. The old arrangement was essentially jamming this signal. I knew something of the kind was happening, but it took a relay box from PhinNeas Electronics (located here in Frederick) to show me what to do- I needed to add a bridge rectifier and run the relay on DC. So simple, yet so elusive.

In short, our little display will be back up in a few days, and kids can marvel at the ‘old’ rotary phones I grew up with.

ALSO- Expect more YouTube videos. I like making them, and people prefer them to blog entries. I’ll drop a link here when it’s done.

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