Help to desing bullet proof Arduino power source...

Discussion in 'The Projects Forum' started by AlexLPD, Feb 17, 2015.

  1. AlexLPD

    Thread Starter Member

    Aug 22, 2010
    Hi to all... Im currently developing some systems with arduino, and the meain reason of failures is due to electric noise, since I learn how to isolate the noise from the control boar using snubbers and varistors ...
    (Thanks a lot for the help of this forum).

    The next big deal is the power source, because even with the proper protection on the board, the main lines, can and have lots of noise.

    I want to desing a power source near bullet proof, with a good filtration and protection of transcient voltages, and 110/220. Capability.

    I design an overly big filter for a cellphone type adapter... but it dont offer a very good filtration.
    This is the filter;

    So I start by thinking in using a regular transformer to have some protection from transients... next to add a bridge rectifier with capacitors to filter some noise in the raw state and after that using a LM317 to have a proper filtration to 7Vcc... and after that a good and large capacitive filter...

    I think the power source will be good from 230 to 90VAC due to the 10:1 relation of transformation... this will provide me with a 23 to 9 VAC good to be used on the diode bridge and after in the regulator stage...

    I need 6 to 7 VCc for the arduino to work properly.

    I have this in mind... Sorry if made some mistakes, I have no formal electronics background.


    The C1 and C2.. ceramics... 50Vac and 0.475uF or smaller?

    Thanks in advance.

  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    The noise that is bothering the Arduino is not coming from the AC line; it is self generated, usually when the Arduino is used to switch highly inductive loads like relays, solenoids, motors, etc. Those problems are usually not much helped by additional "filtering"; rather by use of isolated power supplies for the loads, using opto-isolation, snubbers on the inductive stuff, understanding single-point grounding, keeping the low-level wiring separate from the high-power wiring, etc, etc....
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Bullet proof? I think a bullet would easily pass through those parts.
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  4. paulktreg

    Distinguished Member

    Jun 2, 2008
    Just a couple of initial thoughts..

    You have no smoothing capacitor between the bridge and the LM317.

    You can't use a linear power supply for universal AC input voltages. With 230VAC input you'll get going on 30VDC plus on the input of your LM317. Pull 1A from your power supply and that's over 20W which will make your LM317 scream without a substantial heatsink.
  5. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    I was thinking some Kevlar caps might help.
    Reloadron likes this.
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    DO NOT PUT C1 WHERE YOU DREW IT. It will probably (literally) explode.

    Most of the caps you drew belong where C2 is. Consult the data sheets for the LM317 for recommended bypassing. Then tell you the current draw of your load and we can help you size the bulk cap (C2).
  7. Reloadron

    Well-Known Member

    Jan 15, 2015
    Seriously I would think about what MikeML covered in post #2.

    On a less serious note if you really want some bullet proof LM317s I can sell you a few. They employ the use of a special space age coating that forms a sort of bullet proof vest for components. It's a proprietary design, however, as can be seen in this unaltered picture it works quite well.

    LM317 Bullet Proof.png

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  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
    Nice, is that an Internet clip or your own? 317 is dated 1979!
  9. Reloadron

    Well-Known Member

    Jan 15, 2015
    Actually that was my own doing. The board I used is an old Alarm-Saf DC Power board dated 1988. I tried to find a spent bullet with the rifling marks but had to settle for a new bullet. :)

    absf and GopherT like this.
  10. pwdixon


    Oct 11, 2012
    Only an American would have a choice of a spent or a new bullet, in the UK most would never even see a bullet so we wouldn't know the difference anyway.