| Electronics > Beginners |
| Arduino Data Over Power Help! |
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| HiSmartAlarms:
Hello! Im new to the EEVBlog Forums and I need help with a project. Im working on a model train layout and want to make my own DCC system. Except, my layout is small and so is my budget, so having a proper DCC layout is not a good choice for me. So thinking, I have a good and young mind, I can surely make something in place of DCC with arduinos! And I was correct; but realizing that there is only two rails (One for ground and the Other for signal) I need to give power over the rails. I've seen this done before, but they seem to only run at 5v or so. I need to use a transistor or something to increase that to 12v to power the old dc motor for PWM. I've got that bit working but If anyone could, please give me a schematic to follow. I've tried something already and ended up blowing out an arduino nano. All help is appreciated! 73, KE8GDP (HiSmartAlarms) |
| Whales:
> I've tried something already and ended up blowing out an arduino nano. Whatever you do: don't wire your arduino directly to the rails. Your Arduino's output pins are only rated to deliver a few mA whilst your trains will draw many amps. I'm not familiar with DCC, but my starting point would be to discover the exact voltage waveforms your trains expect. ie is it a 5-12V waveform, a -12 to +12V waveform, etc. This source suggests the latter, but I might be wrong: http://www.circuitous.ca/DCCvolts.html |
| HiSmartAlarms:
Thank you, im trying to use the UART to power a transistor to send a character over the rails, so it would only be one way communications and only a singal character every now and then. And since the arduino has a V in pin which has like a 7-12v input I can just power the arduino from the rails with a cap and a diode, but one thing I'm wondering is how to convert that 12v back down to TTL logic levels. |
| Whales:
Ah, sorry. I thought there were some DDC standards. You are instead trying to implement your own custom signalling system? > but one thing I'm wondering is how to convert that 12v back down to TTL logic levels. A resistor divider can take the 12V signals down to something the Arduino can handle (ie 0-5V). If your voltages can go negative then you will also want to add a diode in to prevent things going too far below 0V. |
| ledtester:
Found these articles: https://electronics.stackexchange.com/questions/1654/injecting-a-communication-signal-over-dc-power-supply-lines https://www.electronicdesign.com/communications/simple-circuit-communicates-over-low-voltage-power-lines and apparently this is how DCC works: https://electronics.stackexchange.com/a/194489/95488 and there is DC-BUS by Yamar: https://yamar.com https://en.wikipedia.org/wiki/DC-BUS |
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