Introduction: Wear to Glow:A Palm Heat Powered Flashlight

About: Hi. I am Abtahee from Bangladesh. I am a student of 11 th grade. I am interested in programming and robotics. But my main concern is researching about renewable energy source.Apart from that I love gaming and …

In this instructable, I am going to show you an amazing flashlight which glows immediately after grabbing it in your palm without any external power source. It uses your body heat to power itself. The light is bright enough to find anything and read in darkness.

Step 1: Concept

I have used peltier modules to generate power from heat. When a temperature difference is created between two sides of the module, it generates electricity. Human body temperature is always 5-6 degree more than environmental temperature. Using this temperature difference, I am going to power the flashlight.

Peltier modules generate about 50-60 mV when they are in contact with the hand. So I have used a ltc3108 booster module which can boost ultra-low voltage to 5V.

Step 2: Tools and Materials


  • Glue gun
  • Soldering Iron
  • Anti cutter
  • Measuring Tape
  • Wire cutter
  • Pliers


  • 2 Peltier modules
  • 3 white LEDs
  • Ultra low voltage booster( Click to buy it)
  • PVC sheet
  • Wires and jumpers
  • Heat sink compound( if you can't get it, you can use toothpaste)
  • Electric Tape
  • Decorative Tape
  • Velcro straps

Step 3: Preparing the First Part: the Heat Sink

Step 1: Attaching Peltier modules

Stack two Peltier modules together using heatsink compound in the surface of the Peltier. Now attach the cold side(the side where the model number is written) with the heatsink in the same way. Mount the Peltier modules using hot glue.

Step 2: Making the belt

At first, take a rubber coated wire and the heat sink. Now put the wire to the gap of the heat sink like the pictures so that it creates D-shaped hooks on two sides of the heat sink. Now use hot glue to join the wire with the heat sink more strongly so that the wire doesn't come out of the wristband.

Now take velcro straps and attach it to the hooks like the pictures by using hot glue or tape.

Step 4: Preparing the Second Part:Making the Box

  • Step 1:

Cut 5 Pvc pieces in the following measurements:

1 piece (7.5cm*4.5cm)

2 piece(4.5 cm*1.5 cm)

2 piece (7.5 cm *1.5 cm)

Now make a box with the pieces using a glue gun.

(Note: You can fit the size according to the size of your heatsink. but make sure the circuits and the wire fits in the box)

  • Step 2:

Make three holes at the front of the box and attach three LEDs in the box with hot glue.

Step 5: Modification of the Booster Circuit

1. Remove two capacitors at the bottom.

2.Solder 1+3 Vout at the bottom right corner of the circuit, like the picture.

Step 6: Wiring and Circuit Diagram

Connect the LEDs in parallel and connect them to the Vout terminal of the booster circuit. Cover the conductive sides of the LEDs with a glue gun.

Connect the two Peltiers in series. Then connect the red wire to the positive terminal of Vin of the circuit and black wire to the negative terminal.

Step 7: Combine It All

keep the circuit inside the box . Then attach the heatsink with the box using hot glue like the picture. Make sure, you have covered the conductive areas of wires and the circuit.

Step 8: Decorate It However You Like

You can use paper or decorative tape to decorate the thing. I have decorated the thing with silver decorative tape and covered the wires and glues.

Step 9: And It's Done

Now you have done making the amazing flashlight. Just grab it in your palm or wear it and the LEDs will glow immediately. You can use your left hand as a lamp while reading a book wearing the flashlight or walk in the darkness.

The LEDs will glow about 20 minutes until your hand gets cool. Then you have to wait for two to three minutes so that your palm can regenerate the heat.

Make it Glow Contest 2018

Participated in the
Make it Glow Contest 2018