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

tjbaudio

looking at the spec sheets the 74141 runs 25ma, the LM317 and put out 1.5A so figure 2A in at full load.
Also looking at the info on that page I think you need to look at the hookup schematic.  http://www.national.com/mpf/LM/LM317.html#Overview

Terry King

... 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.
[/quote]

Hmm. How is the LM317 affecting the 5V??

I think the LM317 should be powered from the external supply, not connected to 5V...

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

stoopkid

Yes, thats what i meant by in parallel with the 5v regulator. I have them both running straight off the power supply and I get similar results.

The thing is though, the nixie tube works fine off the 750ma power supply, as long as i get the 5v somewhere else. So i found a 1.6A power supply, and I still have the same problem, even though more than twice as much amperage is available. I thought this was weird because obviously the nixie tube is getting enough power from 750ma, which leaves more than 750ma more available for everything else. Is this an incorrect assumption?

stoopkid

Tt lights fine when i manually wire the nixie. The 5v stays 5v, the 1.5 drops a little but the transformer still lights the nixie fine. Its only when i have it wired to the 74141 that I get this problem.

Terry King

This is sounding strange... 

Maybe high-frequency noise / coupling??  Make sure you have a bypass capacitor (say .1uf) right across the 74141 Vcc-Gnd supply. Make sure you have a similar value (but you may need a 200v or more rating) across the DC output of your Nixie power supply...

Something invisible other-than-DC seems to be happening here. Maybe. 
Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com

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