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Topic: Transformer draining voltage from arduino trhough LM317t (Read 1 time) previous topic - next topic


Mar 13, 2011, 11:35 am Last Edit: Mar 13, 2011, 11:37 am by stoopkid Reason: 1
I'm trying to use my LM317t to take the arduino 5v to 1.5v, which is the voltage I need for my transformer to power my nixie tubes. I can use my nixie tubes off a AA battery from the transformer just fine. And I can get 1.5v out of my LM317t just fine. But when I try to connect the 1.5v into the transformer, my arduino voltage drops to 3 to 4v. This makes my 74141 not work, and I would imagine isnt good for the arduino/atmega. Can anyone help me out, what's going on here?



Mar 13, 2011, 12:08 pm Last Edit: Mar 13, 2011, 12:12 pm by Graynomad Reason: 1
I suspect your nixie tubes draw way too much current for the poor little Arduino regulator.

Use a separate power supply.

I don't know much about nixie tubes, they are high voltage right? But that would translate to high current on the other side of your transformer I think.

If the above is not the case then you have a fault in your wiring.

Rob Gray aka the GRAYnomad www.robgray.com

Terry King

I'm trying to use my LM317t to take the arduino 5v to 1.5v...

Hi, Are you running all this from the USB??  Better to get a 9V to 12V external plug-in supply, and

1. Plug it into Arduino External power jack. Power the Arduino that way.
2. ALSO feed the LM317 from the 9 Volts. It will still put out 1.5 V (Or whatever voltage you have set with the resistor ratio; I assume you have that figured out)..

Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com


Hmm yeah I figured I should try powering it differently before asking. Thank you for the tips, I'll give them a try tomorrow.


Mar 14, 2011, 02:28 am Last Edit: Mar 14, 2011, 02:37 am by stoopkid Reason: 1
Hmm, it's still not working, even with a 750ma power supply. The only way to get it to work is to give the 74141 its own separate 5v source. The LM317t is draining it's 5v down to 3-4v still, whether It's in parallel with the 5v regulator or pulling from the 5v regulator. I'm only using one nixie tube, could it require more than 750ma?

My multimeter only goes up to 200ma, and its more than that.

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