DC Monkey

Ever get bored of the same old project boxes?
The Altoids mint tin or Radio Shack plastic project boxes are commonly used as cases.
There are many other creative and interesting alternatives out there.
For this project, we use gourd left-overs.
Yes, that is right, a gourd. http://en.wikipedia.org/wiki/Gourd
Throughout history gourds have seen many uses - from canteens to musical instruments.
Today, gourds are used in the craft world to fashion decorative vases and bowls.

For this Instructable, we use the tops of two gourds to make a combination voltmeter and variable DC power source.
The fez hat is a knob that adjusts the voltage.
This build is essentially the same as another Instructable
http://www.instructables.com/id/How-to-Build-a-Bench-Top-Power-Supply/
and
http://www.instructables.com/id/Variable-DC-Power-Supply-for-15/
The circuitry and components are identical.
This build has a couple of differences.
One is the layout of the circuit board, the other is the use of an analog voltmeter vs. a digital meter.
A big thanks goes out these Instructables!

Tools:
Drill
Counter sink bit
Saw
File
Sandpaper
Belt Sander
Hot Glue Gun
Soldering Iron
Jigsaw
Clamps
Permanent Marker
Shears
Centerpunch

Parts:
Hardware -
Gourd tops
Here's is a link to a farm where dried gourds can be purchased online.
http://www.welburngourdfarm.com/
1/4 inch scrap wood
1/2 inch scrap wood
1/2 inch scrap angle aluminum
Lamp fixture parts
Wood screws
Misc. nuts and bolts
Misc. wire
Power cord strain relief
Heat shrink tubing
Plumber strapping
Clear spray paint
WD-40 Cap (optional)
Tassle (optional)
Liquid detergent bottle (optional)
Electronics -
Please refer to the this Instructable
http://www.instructables.com/id/Variable-DC-Power-Supply-for-15/
- Exceptions:
Velleman analog voltmeter - Jameco p/n 316603
Power plug/wire
Green LED and resistor
Aligator clips - Jameco p/n 70991
DPDT power switch rated 250V/2A
4 rubber self adhesive feet

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Step 1: Make the Variable DC Circuit Board

This Instructable doesn't cover the DC circuit board build because it has been well documented elsewhere.
Follow the steps here:
http://www.instructables.com/id/Variable-DC-Power-Supply-for-15/
As noted, there are a few exceptions:
The most obvious exception is the analog voltmeter.
This was chosen because a digital voltmeter requires a battery.
In essense, the variable dc power supply turns into a voltmeter when you turn off the power.
Another difference is the addition of a power LED.
This green LED and resistor combo was added to the DC side of the circuit.
Next, the layout of the components on the circuit board is different than the Instructable mentioned above.
Space was an issue so the components were "squished" closer together by standing them on end.
This resulted in a smaller circuit board footprint.
Refer to the schematic for component layout.
The last difference is a power switch was added between the power transformer and the AC (primary) line.
With the power switch on the primary side, the transformer isn't drawing power when the unit is off.

zack247 says: Mar 21, 2010. 10:58 AM

if a gourd is a plant, wouldn't it rot? or is there something special about gourds, like they have special laser powers or something?

UltraMagnus in reply to zack247Jul 8, 2010. 2:35 AM

wood is a plant too :-P

garagemonkeysan (author) in reply to zack247Mar 21, 2010. 3:15 PM

Ha. The gourds were dried first, before I bought them.
Plus, I added a coat of clear enamel which should help keep bugs away.
BTW - Archaeologist have found gourd fragments dating back thousands of years. Although I doubt my DC Monkey would last that long. : )
Thanks!