Introduction: 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
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!
Counter sink bit
Hot Glue Gun
Here's is a link to a farm where dried gourds can be purchased online.
1/4 inch scrap wood
1/2 inch scrap wood
1/2 inch scrap angle aluminum
Lamp fixture parts
Misc. nuts and bolts
Power cord strain relief
Heat shrink tubing
Clear spray paint
WD-40 Cap (optional)
Liquid detergent bottle (optional)
Please refer to the this Instructable
Velleman analog voltmeter - Jameco p/n 316603
Green LED and resistor
Aligator clips - Jameco p/n 70991
DPDT power switch rated 250V/2A
4 rubber self adhesive feet
Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.
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:
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.
Step 2: Prep the Gourd Tops
First, cut the gourd tops to size.
The inside of the gourds are lined with soft fiberous material.
Sand or grind the insides smooth with a special grinding ball.
These grinding balls are specially made for gourds however, course sandpaper works fine too.
Buy the special grinding balls here:
Once the inside of the gourds are fairly smooth, level the cut edges with a belt sander.
Here's an Instructable for creating a belt sander stand.
The edges must be on a flat plain for the next step.
Step 3: Fabricate Top and Bottom Face Plates
With pencil and paper, place the gourd tops on the paper and trace around the circumference to make a pattern.
Transfer these patterns to a 1/4 inch wood.
Cut it out with a jigsaw.
Unfortunately the photo shows an incorrect template.
The hole for the meter had to be moved lower for clearance.
The correct location of the hole can be seen in other photos.
Step 4: Afix Face Plate to Gourds
Next is mounting the face plates to the gourds themselves.
To do this, make seven (three for the head and four for the body) tabs out of 1/2 inch scrap wood.
Grind each to fit the inside contour of the gourd and flush to the edge of the gourd.
Glue the tabs to the inside of the gourds and clamp them in place.
Let them set overnight.
The next day, center punch each of the tabs.
On a paper template locate and mark each of the center punch dimples.
Transfer those markings to the faceplates.
Drill and countersink those holes in the faceplate.
Screw the faceplate to each of the gourds.
Using a belt sander grind the edges of the faceplates flush with the sides of the gourds.
During this entire process make reference marks on the edges of the face plates and gourds.
The marks keep the faceplate and gourd in alignment.
Step 5: Attach Head to Body
Once the face plates have been attached to the gourd shells, it is time to connect the head to the body.
First position the head to the body and mark where holes should be drilled.
Drill a 1/2 inch hole.
The hole in the body was cut out larger with a coping saw.
This was done to allow some adjustability to the angle of the head.
Use the lamp hardware to bolt the two halves together.
For added strength, add hot glue in between the two halves.
Apply the four rubber feet to the bottom.
Step 6: Install Components Into the Body
It is now time to install all the components.
First position the transformer to the bottom face plate.
Using plumber's strapping, mark then drill holes to the bottom face plate.
Countersink the holes and bolt the transformer to the bottom face plate.
Position the switch and the power cord.
Find a location on the gourd for the switch and gourd.
Be careful because it can be a tight fit.
Drill a hole in the gourd for the switch and notch it for the cord.
Mark, drill, countersink and bolt up the power cord strain relief.
You can add some hot glue to strengthen the strain relief.
Strip the wires and solder the switch in between the power cord and transformer.
Don't forget the heat shrink tubing! : )
Step 7: Install Components Into the Head
Next install the components into the top gourd - the head.
First position the meter and cut out the faceplate per the pattern supplied with the meter.
Depending on the size of the grourd and components the fit can be very tight.
Make sure the components do not touch one another.
In the photos you can see where I had to redo the face plate.
The meter had to be positioned lower to clear the mounting screws.
Learn from my mistakes! : )
Connect the LED, LED resistor and connector together and solder and heat shrink the assembly.
Drill a hole for the LED indicator and hot glue it in place.
Position the potentiometer and drill a hole for it.
Wire it to the printed circuit board.
Drill holes for the plus (red) and minus (black) leads.
Solder and heat shrink the aligator clips to the leads.
Solder the leads to the circuit board after threading it through and knotting it.
Hot glue the printed circuit board to the inside of the gourd.
Connect the output of the transformer to the input of the circuit board.
Connect the voltmeter and screw on the face plate.
Step 8: Make a Character (optional)
Now things get cute.
Create a character!
A monkey theme isn't the only possibility.
The meter can be dressed up to be almost any animal: a panda, a piggy or a rabbit.
The monkey fez was made from the top of a WD40 spray can.
Trace out the top onto scrap 1/4 inch wood.
Cut it out with a jigsaw and fit it to the inside of the cap.
Drill a center hole sized to fit the potentiometer shaft.
Hot glue the wood to the cap.
Next, hot glue the tassle to the cap.
To make the ears cut out a shape from scrap wood and glue them to the sides of the head.
The eyes are sheet plastic.
Find a used liquid detergent container or similar plastic product.
Use a permanent marker to draw in the eyes and cut it out with shears.
Use hot glue to mount the eyes to the face.
You are now finished!
Now wrap it up and give it away as a gift!
Participated in the
Homemade Holidays Contest