====== A Test Power Panel ======

We're going to build ourselves a "power test panel" for testing one or two motors at a time for  workshop demonstrations and for mechanism prototyping.  We've lashed this up a few times in the past, and its proved its usefulness.  Now we'll do it in a tidier, more durable form.

I'm sure we can do it more neatly than the one pictured here: 
https://www.chiefdelphi.com/forums/showthread.php?t=152051
(never mind the text of that thread)

On the panel will be some basic robot electrical components:

  * battery (with SB50 connectors)
  * [[http://www.andymark.com/120-amp-robot-main-circuit-breaker-p/am-0282.htm|120 amp main breaker]]
  * power distribution panel (an old FRC-2015 blue one)
  * some motor controller

In addition, we're going to add a volt/amp meter to check battery
condition and current drawn by things under test: [[https://www.amazon.com/gp/product/B013PKYILS | Volt/Amp meter (Amazon)]]

In order to activate the motor controller, we'll need a souce of PWM data.
Initially, we'll use this one that I built a few years back: 
[[PWM generator with display]].
Alternately, one could buy one or two of these: http://www.andymark.com/Thrifty-Throttle-p/am-2936a.htm
Or we can build somthing using an arduino or other processor.


====== Wiring diagram ======
Here's how we'll wire the battery to the PDB.  Note that we're inserting the measurement shunt for the
ammeter into the negative lead.  This wouldn't be FRC-legal on a competition robot, but is exactly what we
want for our test board.

{{ :power-test-board.jpg?direct&200 |}}

  * Battery + to breaker (red)
  * Breaker to PDB  (red)
  * Battery - to current shunt (black)
  * shunt to PDB (black)

We wire the volt/amp meter unit exactly according to its documentation.  Incorrect meter wiring could damage the meter or cause it to read improperly.  There's a picture on the back of the meter unit.

Be sure to insulate all of these connections with electrical tape.


====== Finished test panel ======
{{ :powerboard-pwm-overview.jpg?direct&400 |}}

===== Closeup of the PDB and meter =====

{{ :powerboard-closeup.jpg?direct&400 |}}