DIY Money Blower Machine

A fun & whimsical way to collect donations for a variety of causes. Depending on the materials you have lying around your house, this machine can be built for free! Even if you have to buy all the materials, maximum cost is less than $15.

This is a minimalistic and easy design for makers of all experience levels! The whole machine takes about an hour to build.

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Materials

1. Cardboard Box (not pictured)

Medium to small, somewhere around 12 in. x 12 in. x 12 in.

2. DC Computer/Electronics Fan

Recommended to harvest one from broken electronics equipment. Otherwise, these can be purchased online from a variety of manufacturers for ~ $5. Here's one website.

3. Power adapter cord (120 VAC to ~ 12VDC)

Recommended to repurpose an unused power cord lying around; old charging cords (e.g. phones, cameras, etc.) are perfect.

4. Saran Wrap

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Tools

1. Wire strippers

2. Scissors

3. Soldering Iron*

4. Hot glue gun

5. Duct Tape (or other heavy duty tape)

*If soldering iron isn't available, tightly twist wires together and coat in hot glue.

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Build it! Pt. 1

Optional: Spray paint, or paint, cardboard box.

1. Cut a 3 in. x 1 in. slot in the top of the cardboard box.

2. Cut windows into the 3 of the sides of the cardboard box.

Be sure to leave at least 1 - 2 in. of cardboard along the edges of each side.

3. Cut the remaining side into a door.

Cut along 3 of the edges (bottom, one side, and top) so that this side opens and closes, with one of the edges as the hinge.

4. Tape saran wrap on the inside of the cardboard box to cover the window holes.

Tape saran wrap onto the farthest most edge. Pull one side of the saran wrap tight and tape to box. Repeat with remaining sides. If there are loose areas, gently pull up tape and re-adhere to box.

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Build it! Pt. 2

1. Cut connector ends off of the computer fan and the power adapter and strip wires.

For the computer fan, strip the red and black wires.

For the power adapter, separate the two wires and strip.

2. Connect the red computer fan wire to one lead of the power strip, and the black computer fan wire to the other power strip lead. Check that the fan turns on when the power adapter is plugged in.

3. If fan turns on, unplug the power adapter and solder the connections together. Coat in hot glue.

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Build it! Pt. 3

1. Glue computer fan on the inside of the cardboard box, in the center of the side with the door.

2. Cut a hole in the center of the cardboard box door to expose the computer fan.

3. Cut a top vent in the cardboard box door.

Recommended to cut small slits, or cover larger vents with skewers or toothpicks.

4. Adhere the cardboard box door to the side.

I found strips of velcro lying around. Other ways to adhere are rubber bands, string, or just hot glue the sides together.

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Test & Impress!

Add a few dollar bills to check that there is good airflow. If it works as expected, use at parties as a fun way to collect money for food + drink, or incorporate into your next fundraiser to collect donations!

If you notice that the dollar bills are getting stuck in the corners, add some angled cardboard rectangles or increase the size of the vent.

DIY Portable Amplifier

As an avid climber, a full day, or weekend, break from my cellphone and e-mail is one of the best perks. Still, like nearly any activity, good music makes it more enjoyable. This desire to merge two of my passions, climbing and music, resulted in this small, yet robust, portable amplifier.

Here's a video of the final system in action.












Materials

•  LM386 audio amplifier

•  3 Capacitors:

C1 = C3 = 220 microF
C2 = 10 microF

• 4 Resistors: 

R1 = 10 Ohm
R2 = 1 kOhm
R3 = 10 Ohm 
R4 = variable 10 kOhm (w/ an SPST or SPDT switch)

• 9 V battery + battery clip

• Speaker (4 - 8 Ohm)*

*Have a broken sound system? Harvest the speaker! Look for one that can fit in the palm of your hand.

•   1/4" (or 1/8") mono panel-mount audio jack

•  PCB Board

• 22 Gauge stranded wire ( ~ 1 ft)

•  Case**

**There are many options! My case is a mini-lunchbox type thing found at a thrift store for $1. Look around the house, or peruse a thrift store for vintage tins, cigar boxes or metal piggy banks. Look for containers made from metal, wood, or rigid plastics.

• Recommended: Piece of wood for speaker mount

This improves audio output by providing a solid resonant surface. This step was somewhat involved (tool heavy), can be accomplished in many different ways, and is entirely optional, so I will just briefly cover this part of the process.


Tools

• Soldering iron, solder + solder sucker. 
• Epoxy or other bonding agent. 
• Wire strippers 
• Highly recommended: Multimeter. 
• For the case, you also need a drill.
• To mount the speaker in wood: a dremel or other wood cutting tool (+ clamps + eye protection)

Build it! Pt. 1

1. Solder wire leads to the audio input.


2. Solder wire leads to the speaker (recommended to use at least 6" leads).











3. Solder wire leads onto the variable resistor (potentiometer) pins.
Check the resistance between the difference potentiometer pins w/ a multimeter before soldering to determine the functionality of each pin.
Aside: Wire color, while entirely optional, helps distinguish the different pin functions. To wire the potentiometer so that the volume increases from the "off" position: Pin 1 goes to ground, pin 2 goes to LM386 pin 3, and pin 3 goes to the positive audio input.

4. Solder wire leads to the switch pins on the bottom of the potentiometer.
Check resistance across switch pins w/ multimeter. This potentiometer switch has a front pin that goes to ground and the left front pin to positive input.






Build it! Pt. 2

If schematic makes sense, skip next two steps (still suggested to build on breadboard first).

1. Build circuit on a breadboard. Recommended to draw out how it will transfer to the PCB board pads.

Connect a battery and check audio input w/ either a multimeter or an actual source (will need a 1/4" or 1/8" headphone cable).

2. Solder LM386 amplifier to PCB board.











3. Solder the battery clip leads and potentiometer switch leads to the PCB board.
The potentiometer leads are inserted between the positive battery lead and the 10 ohm resistor going to the LM386 voltage source pin.
Note: If your variable resistor does not have a switch, it is highly recommended to include a power switch for the battery.


Build it! Pt. 3

1. Solder the remaining components to the PCB board using the PCB pads and/or wires (breadboard pictured for clarity).

A. Connect LM386 pins 2 and 4 to ground.

B. Connect 1kOhm resistor and 10 microF capacitor from LM386 pin 1 to pin 8 (shorter leg (negative pin) of the capacitor connects to LM386 pin 8).











 C. Connect the long leg (positive pin) of the 220 microF capacitor to LM386 pin 5. Connect one side of the 10 ohm resistor to the short leg of the capacitor, and the other side of the resistor to ground. Connect the positive speaker lead to the short leg of the capacitor, and the negative lead to ground.




D. Connect one side of 10 ohm resistor to LM386 pin 6 and other side to positive battery (w/ switch). Connect long leg of 220 microF capacitor to LM386 pin 6 and short leg to ground.












E. Connect the potentiometer pin 1 to ground, pin 2 to LM386 pin 3, and pin 3 to positive audio input.

F. Connect negative audio input to ground.

Case it! Pt. 1

1. Plan + mark location of each of the components.
The potentiometer, or volume knob, power switch, audio input, and speaker are installed on the exterior. The PCB board and battery are on the interior.










2. Drill two holes in case exterior for the potentiometer knob and for the audio input.
If case is not metal, recommended to include a sheet of metal to provide a better ground for the audio input.

3. Remove screw heads from potentiometer knob and audio input. Push potentiometer knob and audio input through the holes and reattach screw heads.

4. Check connections w/ a multimeter and/or an actual audio input (will need a 1/4" or 1/8" audio cable).







5. Dab epoxy onto bottom of case to adhere the PCB board.
To secure the 9V battery: use velcro strips, or make a quick fabric pouch and epoxy the pouch to the case.

Case it! Pt. 2
1. Mount the speaker in wood or in case exterior.
There are different options depending on your chosen case and available tools. It sounds great w/ wood, otherwise you can also mount it directly to the exterior of the case.

One option is to follow the design featured in this tutorial:

A. Cut a piece of wood to fit inside the case (bottom slab). Cut a hole in the middle large enough to pull the speaker through.
 



B. Take a thin piece of wood and cut a notch out. The notch should be sized so that the screw holes of the speaker frame sit on top of the wood.










 C. Optional: Screw speaker into top wood ring. Screw top ring into bottom slab.

Test & Go Adventuring!

Test the electrical connections by plugging in an audio source (e.g. electric guitar or mp3 player). Check that the potentiometer effectively controls the volume and that the switch turns the system on/off. Once everything is working, coat electrical connections in epoxy.

Take your new portable amplifier to bring music to your next outdoor adventure!

LED Proximity Sensor Gloves

 
This is a minimalistic design for a proximity sensor glove: a light-up glove that dims in brightness when an object, or person, is close to the sensor. This project costs less than $10, although it does take some time to build (1 - 2 hrs).

This is also a modular design, meaning that it is easily customizable and can be used in other projects.

Here's a video showing the glove in action.

Materials

-- Gloves (fingertips optional)
Pretty much any type of glove will work. I chose simple cotton ones (that are well worn and have character) because it's easy to sew components into these gloves and, if necessary, can easily (& cheaply) be replaced.
-- LEDs!
I had 5mm white LEDs on-hand, so I used 10 for one glove. As long as each LED has appropriate resistance, you can (pretty much) add as many as you want.
I strongly recommend getting surface mount LEDs or wearable LEDs. They are a bit more expensive, but are much more aesthetic for this type of project and are waay easier to sew.
-- Conductive thread
This is one way to connect + attach the LEDs. I chose conductive thread b/c it looks cool and incorporates the circuit into the glove material, acting as both a conductor and an adhesive. Other options include wire or alligator clips.
Disclaimer: When using conductive thread, be super careful of short circuits. I set my conductive thread on fire more than once during this build process..
-- Photoresistor
-- Five 1 KOhm resistors (one for each pair of LEDs)
The value and number of your resistors may change depending on your battery + LED type.
-- 9V battery + battery clip
-- Switch (optional)



Tools 

-- Scissors
-- Sewing needle
-- Hot glue gun, epoxy, or other quick-drying adhesive.
-- Soldering iron (optional)
You can build the glove without a soldering iron by tying conductive thread tightly to a component, then coating in hot glue or other adhesive.
-- Multimeter (highly recommended)
A multimeter is super useful for checking electrical connections.


Build it! Pt. 1

If a breadboard is available, use it to test the circuit.

1. If you have a switch, connect one end to a battery clip lead.
Solder the two wires together, or use conductive thread + hot glue.

2. Determine layout of the photoresistor(s), LEDs, and resistors.
You can follow my schematic or you can add more LEDs and/or photoresistors (recommended b/c it's cooler). Here's a helpful website to calculate the circuit resistance. Remember that the photocell also adds some resistance (mine was between 300 Ohms and 1 MOhm).
In my layout, two LEDs are connected in series with a resistor, as in the breadboard photo above. These in-series LED pairs are then connected in parallel with all other in-series LED pairs.
Aside: Diode forward voltage & current depends on the color. These white LEDs were ~ 3.4 VDC and 20 mA. Use Google or this page to find forward voltage and current for your specific LEDs.

 




3. Turn glove inside out and mark location of the LEDs, resistors and photoresistor(s).

4. Sketch the positive and negative connections onto the glove w/ a pen. Label the + and - lines.
This step is especially helpful b/c 3D circuits can be a bit confusing.








Build it! Pt. 2

1. Attach the photoresistor to the glove (and add a positive battery lead to the glove).
Make a slit in the glove or push the photoresistor wire legs through the fabric (be sure the legs are on the inside of the glove). To hold it in place, dab hot glue or sew legs to glove with regular thread.

Tie conductive thread to one end of the photoresistor (either leg works), and sew thread through the glove to the bottom. Leave a few inches of thread at the end for the the battery connection. Coat connection in hot glue.





2. Attach a resistor to the positive leg of one LED. Repeat for one LED in each set of LEDs that are in-series (5x for this configuration).

Wrap the two ends together and, if possible, solder the connection. Remove excess wire and coat in hot-glue to adhere connection and cover sharp ends.








Build it! Pt. 3 

1. Attach the LED + resistor to the glove.
Poke the ends of the LED through the glove (or make a slit). Tie conductive thread to LED legs and coat in hot glue to hold components in place, and to cover sharp ends.
Be careful to avoid shorting the LED legs with the conductive thread.

2. Connect the LED + resistor to the open leg of the photoresistor.
Sew conductive thread from the resistor leg to the photoresistor leg, then tightly tie thread to photoresistor leg. Coat connections in hot glue.









3. Connect the next in-series LED.
Connect the positive leg of the next in series LED to negative leg of the previous LED.
Depending on the type and number of LEDs you are using, you may have one, two or more LEDs in series w/ the first LED + resistor.

4. Repeat Steps 1 - 3 for all LEDs in parallel.


























Build it! Pt. 4

1. Once all the LEDs + resistors have been installed, add in a negative battery lead.
Consider where you want to put the battery before adding in leads. You can attach the battery directly to the glove, hide it inside the glove, or install long leads to allow the battery to be placed elsewhere on your body.
My initial design used conductive thread for both battery leads, but this shorted the glove so many times I replaced them with an alligator clip in the final design. This works much better, is safer, and is seriously recommended over conductive thread. If you don't have an alligator clip, any insulated wire will work.




2. Label the positive and negative battery leads.

3. Optional: Solder the battery clip leads to the glove battery leads and dab with hot glue.
Alternative options include alligator clips or twisting wires together + coating with hot glue.

Test & Wear!

Be sure to test your design BEFORE you wear it because if there are shorts in the conductive thread it will probably catch fire. So, please be careful and be sure that the positive and negative sides of the circuit do not touch.
The connections can be a bit finicky. Be patient and check the electrical connections w/ the battery or a multimeter (if you use a battery, be careful to avoid shorting the circuit). Fix and add more hot glue as necessary.
Once you know it works, put on the glove(s) and impress your friends!
Happy hacking!