Hi,
I need help with a schematic for a power supply, 12v adjustable 5-8amp. Small footprint 4x4x4inches is this possible? Im a idiot when it comes to schematics but i can solder very good, so any schematic in begginers format or good explainations would be very helpful.
Thank you Rhett from NTX

 

Hello,

What range must the output voltage have?

Greetings,
Bertus

 

needs to be from 2-12v so i can break in brushes at and test amp draw

 

Hello,

Is the powersupply to be made from mains?
This is perhaps not cheap but small.
Take a look at the LT1083 regulator.
Here is a datasheet of this chip.

Greetings,
Bertus

 

You'd really be much better off using a switching PWM supply than a linear regulator.

You asked for something small, but one that measures 4"x4"x4" at 100w and powered by the mains is a pretty tall order for a beginner's project; it would be rather expensive to build as well.

You might start off by converting an ATX-form factor computer power supply to a bench supply. Google will give lots of "hits" on this type of project. If you don't have an older PC-compatible computer sitting around idle, it's a good bet that somone you know has one. This is a very inexpensive way to get started.

From there, you can use a 555 timer wired for low-speed PWM to drive a MOSFET gate (an IRFZ24, IRFZ34, or IRFZ44 would be a good candidate) to switch the ground side of the motor's circuit. You'd also need a "flywheel" diode across the motor's connections to prevent the reverse EMF from destroying the MOSFET when it was switched off.