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Building my own power supply. Need a sanity check. — Parallax Forums

Building my own power supply. Need a sanity check.

RICoderRICoder Posts: 91
edited 2009-01-26 02:39 in General Discussion
I have already built out a regulated 5v power supply that can use a wall-wart and push out some good 5v. That said, I recently got the propeller (having only used s BS2 on a BoE before), and found that it takes VIN from the 9V battery and puts out 5v.

So, I was going to get a couple of boards printed and make a few home-made power supplies for my projects. Now that I look at the prop, I am thinking that I'd like to make my boards so that they can take in a wart and put out either or both 5v and 8v.

I drew up a schematic (attached) using a 5v regulator and a variable regulator...can you guys take a look and tell me if it is going to explode or not?

Thanks.

edit: FYI I think that C4 should be 50uF instead of 100uF...or maybe 10uF...
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Comments

  • SRLMSRLM Posts: 5,045
    edited 2009-01-22 06:18
    The propeller runs on 3.3 volts, not 9V, 8V, or 5V. On a side note, I found some nice 3 Amp regulators for both 5v and 3.3v for only a couple bucks a piece. The catch is that they have a different pinout. The 3.3 volt version is LD1085V33. They use 10uf caps BTW.
  • RICoderRICoder Posts: 91
    edited 2009-01-22 06:21
    Allow me to retract and re-state. I have a propeller "prop stick usb" I think its called (I don't feel like going downstairs to look). Its the one that you plug the USB directly into, and it takes VIN according to the kit schematics...and the breadboard I built out to test it. I misspoke a bit, I realize it uses 3.3, but the prop-stick seems to have its own regulator built in.
  • SRLMSRLM Posts: 5,045
    edited 2009-01-22 06:27
    Ah. Still, you may want to make a regulator setup for 3.3v if you ever get a regular prop.
  • RICoderRICoder Posts: 91
    edited 2009-01-22 06:32
    Good point...but back to the initial question...and maybe I'll just restate it...
    a) Can I build a board that takes power from a DC wall wart and have multiple outputs at multiple voltages?
    b) In my above schematic, assuming that the resistors for the variable regulator are correct, will I get what I want which is 5v and 8v (or 3.3v if I so wish it, maybe I'll make a 3 pointer)?
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2009-01-22 06:49
    RICoder,

    a) Yes

    b) Yes, if you wanted to get tricky, you could take the difference of 8V and 5V and provide 3V (<-enough to power the Propeller) with the 5V/8V schematic you currently have.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • mikedivmikediv Posts: 825
    edited 2009-01-22 19:46
    RICoder·another thought most 12V wall warts actually put out enough volts over the listed 12 to run a 7812 12 volt regulator and a 7805 5 volt regulaotr and the Lm2937 3.3 volt regulator I used an old zip drive 12 volt wall wart a few caps and such and made a very small the cirucuit board anyway +12.+5,+3.3 power supply I also included a 9 volt battery clip lead to use those 6AA batery packs for making it portable while the zip drive wall wart states 12 dc for output its actually 17 volts hope this helps
    Oh RICoder if I am not mistaken the propsticks are the ones that take in 9V battery power and then have the 3.3 output I do not hink the stand alone prop chip has the regulated out put on pin 32 I made that mistake I have the propstick so when I built a project with a plain 40 pin prop chip I powered it up with 9-10 volts and it got red hot before I realized my blunder

    Post Edited (mikediv) : 1/22/2009 7:51:45 PM GMT
  • Dave LDave L Posts: 5
    edited 2009-01-24 20:16
    RICoder said...
    I have already built out a regulated 5v power supply that can use a wall-wart and push out some good 5v. That said, I recently got the propeller (having only used s BS2 on a BoE before), and found that it takes VIN from the 9V battery and puts out 5v.

    So, I was going to get a couple of boards printed and make a few home-made power supplies for my projects. Now that I look at the prop, I am thinking that I'd like to make my boards so that they can take in a wart and put out either or both 5v and 8v.

    I drew up a schematic (attached) using a 5v regulator and a variable regulator...can you guys take a look and tell me if it is going to explode or not?

    Thanks.

    edit: FYI I think that C4 should be 50uF instead of 100uF...or maybe 10uF...
    ·RICoder,
    ·Thank you for your post. It appears that I overlooked one item that I was searching for, and found it within your post. This will help immensely with my own project-enough so that I can put the draft together and submit for redline and review. (BTW, I'll have to make modifications to the schematic, adding extra filtering etc, due to the fact that (If approved) it'll be attached to flight hardware. I do hope that you do not mind me borrowing your schematic and doing modifications to it?
    Dave
  • RICoderRICoder Posts: 91
    edited 2009-01-26 02:39
    I've modified this design somewhat over the past week or so and started using it with a prop-stick and 3 standard servos. I am getting a new multimeter next week at which point I'll poke around a bit and let you all know what I find. The setup is really nice, I'm sure other people have done it, and probably better, but i'll post the schematic anyway in case it helps someone.
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