Shop OBEX P1 Docs P2 Docs Learn Events
Curse ground loops, bless Erco! — Parallax Forums

Curse ground loops, bless Erco!

RS_JimRS_Jim Posts: 1,764
in General Discussion
With ground loops I have managed to destroy 2 dip props, 2 QS boards, probably a proto board, various component parts and a propplug! I thought I had the ground loop problem solved, but NO I continue to destroy things! Bless Erco as years ago he turned me onto a $4.99 boost convertor that outputs up to 24 volts or more. I connected the converter to a large USB battery pack and set the output to the required voltage to run my various boards that want +7.5 V to 9V. That should eliminate any ground loops. I just wish I had remembered that I had it sooner. It powers the boards just fine. Now all I have to do is replace the propplug and a few prop chips. The hardest loss will be the protoboard as I don't have the facility to replace the prop on it. I won't know if the protoboard is gone until I get the new propplug and rev D obsoletes all of my Mini-USB cords. Oh well such is life!
Jim

Comments

  • Duane DegnDuane Degn Posts: 10,588
    If you send me your Protoboard, I'll replace the Prop on it. I have Propeller chips on hand so I just need the board.
  • RS_JimRS_Jim Posts: 1,764
    Thanks,
    PM your address
    jim
  • macrobeakmacrobeak Posts: 354
    RS_Jim wrote: »
    With ground loops I have managed to destroy 2 dip props, 2 QS boards, probably a proto board, various component parts and a propplug! I thought I had the ground loop problem solved, but NO I continue to destroy things!

    Jim,
    Sorry to hear about the loss of your Prop modules.
    How did you manage to get such a destructive ground loop?
    An explanation or schematic may help someone else making the same mistake!

  • Duane DegnDuane Degn Posts: 10,588
    I provide an example of the wrong way to connect grounds in this post.

    Phil Pilgrim patiently explained what was wrong with my setup.

  • xanaduxanadu Posts: 3,347
    Jim,

    What was your previous supply?

    It sounds like you removed the potential for an AC ground loop. I love the USB QC3 battery packs, combined with an adjustable trigger you can have lots of adjustable power supplies.
  • Peter JakackiPeter Jakacki Posts: 10,193
    Maybe the problem is with off-line switched mode supplies because I notice that with some I can get quite a bite from the DC end. The laptop supplies though are earthed since all our GPOs here always have 3 pins, so the earth kills the nasty bite or else it is because the internal cap goes to neutral and neutral is earthed and not reversable. Were you using non-earthed supplies at the time?
  • RS_JimRS_Jim Posts: 1,764
    Peter,
    My previous issues with ground loops had to do with powered USB hubs so I got rid of them and only use passive hubs at this point. I thought I had checked the supply in question, but appearantly not. I do wish you had your USB chip on a board that could be added to a P1 product. It would be nice to get USB and a/d for 1 price.
    Jim
  • Peter JakackiPeter Jakacki Posts: 10,193
    Hey Jim, can you use the QSOP24 smd?
    I might put that little critter onto a board as a serial module, probably mounted sideways with a row of pins on the bottom as a sip10 or something. These will be fitted with a micro USB socket so you can use any suitable cable.
  • ercoerco Posts: 20,256
    "Curse ground loops, bless Erco!"

    WAIT, said Willy Wonka. Strike that, reverse it.     :)

    I bet you mean these MT3608 modules: https://www.ebay.com/itm/382609548300

    They are great, especially for a buck. I've stockpiled a few.

    Thanks for the thought, a little extra blessing never hurts. Whit, now you have some help in blessing people!
  • RS_JimRS_Jim Posts: 1,764
    Peter Jakacki wrote: »
    Hey Jim, can you use the QSOP24 smd?
    I might put that little critter onto a board as a serial module, probably mounted sideways with a row of pins on the bottom as a sip10 or something. These will be fitted with a micro USB socket so you can use any suitable cable.

    Peter,
    That would be fantastic! I could plug that right onto my proto board and use the A/D and the USB.
    macrobeak wrote: »
    RS_Jim wrote: »
    With ground loops I have managed to destroy 2 dip props, 2 QS boards, probably a proto board, various component parts and a propplug! I thought I had the ground loop problem solved, but NO I continue to destroy things!

    Jim,
    Sorry to hear about the loss of your Prop modules.
    How did you manage to get such a destructive ground loop?
    An explanation or schematic may help someone else making the same mistake!

    The board is a Parallax 32212 Proto Board what has onboard regulators for a 6-9 volt DC input. The power was input from a Radio Shack 9 volt DC wall wart. As Peter mentioned, the laptop is powered by a 3 wire cable from the mains. the wall wart is just a two wire and it is a switch mode supply. I thought I had measured for ground loops between the wall wart ant the negative on the USB lead. When I was blowing up Quick start boards, I found that I had a 48 VAC ground loop on my powered USB hubs. Hence forth, unless I am powering from USB, I will use batteries to power my Propeller boards.

    Erco thanks for the link to the switched DC-DC supply, I think I will be needing a couple more. That is 1/5 the price that I paid for the first one.

    Jim
  • xanaduxanadu Posts: 3,347
    I've been using this as my desktop supply and love it. I have the 15W, there's a 30W too.

    https://www.amazon.com/gp/product/B083BPTCB7

    IMG_1577.JPG
    IMG_1577.JPG
    756 x 567 - 133K
Sign In or Register to comment.