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18V DC to 9v DC for powering Proto board — Parallax Forums

18V DC to 9v DC for powering Proto board

GeeksGoneBadGeeksGoneBad Posts: 100
edited 2011-05-23 16:32 in Propeller 1
Hey everybody!

I'm working on a project with the Easydriver Stepper driver board and I've got it all working except for one thing

I'm using an 18v power supply to power the Easydriver and would like to pull the 6-9v off of that to power the Proto Board too

is that a practical idea and what's the easiest way to step down the 18v to 9v (or so) - I tried a simple voltage divider and even though I got 7.5v it would not power the proto board for some reason

I'm open to any ideas! :)

Comments

  • LeonLeon Posts: 7,620
    edited 2011-05-22 14:12
    A voltage divider won't work, and a linear regulator will probably run too hot. You need a buck converter; I'd use one of the National Semiconductor Simple Switchers.
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2011-05-22 16:23
    Simple switchers are great and they are the only regulators I seem to use now. If you get a 3V one you can directly power the propeller from that 18V supply, and the regulator will run so cool it won't need a heatsink.

    However, the parts are a little hard to get hold of. I get the simple switchers from Futurlec but the inductors are not so common - you need 333uH and 1 amp inductors. I have found a source in Australia (Rockby) for $2 ea and they do exist in catalogues from all the big suppliers worldwide (Digikey etc) but you have to search through lots of other parts eg same inductance but much lower current rating.

    It may be easier to use a different supply/wallwart/plugpack as these are so cheap nowadays, eg a 9V one.
  • GeeksGoneBadGeeksGoneBad Posts: 100
    edited 2011-05-23 04:47
    Thanks for the advise guys - I will check out the Simple Switchers

    I started out with a 9v power supply - but I'm getting more torque from the stepper at 18v and this is going to drive my leadscrew on my metal lathe so I think I'll need the torque :)

    Jamie
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-05-23 05:55
    You could also buy a ready-made solution. I've used several of Dimension Engineering's regulators. It's probably a more expensive solution but it's fast and easy.

    Duane
  • TonyWaiteTonyWaite Posts: 219
    edited 2011-05-23 06:51
    Hi,

    I would echo Leon and Drac's recommendation for 'Simple Switchers'.

    Even easier, I see from another thread that thes are now available in *module* form!

    Regards,

    T o n y

    http://forums.parallax.com/showthread.php?131830-A-New-type-of-Switching-Regulator-Simple-Switcher-Power-Module-LZM12002
  • Duane DegnDuane Degn Posts: 10,588
    edited 2011-05-23 07:35
    @Tony, I just read through the thread you linked to (thanks). I agree those "modules" are a good solution. I think the part itself is being referred to as a module. I believe the part still requires external components and a pcb in order to use the part.

    I'm I missing something?

    Duane
  • Zap-oZap-o Posts: 452
    edited 2011-05-23 07:55
    I am using 24Volts on a stepper motor project at the moment. Here is what I have:

    LM7805 brings the 24V to 5V - LDO at 3.3 volts for the prop.

    You could use diode/s too.
  • AleAle Posts: 2,363
    edited 2011-05-23 10:09
    I support the simple switchers like the LM2576 and friends. There are higher frequency versions that need smaller inductors (value/size) and probably have less ripple too.
  • Alexis64Alexis64 Posts: 42
    edited 2011-05-23 10:50
    All parts are available from Newark, Farnell, Futurelec etc ...

    vreg.jpg
    vreg.jpg
    1024 x 578 - 41K
  • Dr_AculaDr_Acula Posts: 5,484
    edited 2011-05-23 16:32
    I found this little module from Sure Electronics http://www.ebay.com.au/itm/AX3022-Voltage-Regulator-Adapter-Step-Down-2-5-18VDC-/250824486063?pt=LH_DefaultDomain_0&hash=item3a664decaf

    $10 including shipping, input 4-24V, output adjustable 2.5 to 18V, 1.5A, tiny 1 inch square board, all prebuilt.
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