How to Make a HEXBUG Nano to Be Activated by Light.

This instruction is to make a HEXBUG nano to be activated by light.

HEXBUG nano is a fun toy which moves like a real bug. I want to use it to surprise someone who open the box contain a dozen of the HEXBUG nano. But the HEXBUG have only a toggle switch for activation, so the bugs cannot hide silently in the box.

We can add a photo switch to activate the bugs only when they come to bright place. It works well, and the modification doesn't change the look of HEXBUG nano.

It is very simple circuit, but little difficult when you solder SMD transistors. Check the schematics.

Step 1: What You Need

You need below stuffs:

1. A HEXBUG nano
You need the HEXBUG nano. I recommend the one which has clear window on the top.

2. SMD Transistor
I have tried 2SC4116 and 2SC3325. 2SC3325 is better because it has bigger body and larger collector current.
http://akizukidenshi.com/catalog/g/gI-00628/

3. Photo diode
I used PS1101W.
http://akizukidenshi.com/catalog/g/gI-01674/

4. A design knife
You need it to uncover the bug.

5. A screw driver (+)
You need it to remove battery cover.

6. Soldering iron and solders
You need them to build the circuit.

7. A tweezer
The parts is very small. You need it.

8. A mini knipper
You need it to cut off the wire of the toggle switch.

9. A double sided tape
You may need it to hold parts when you solder them.

10. A instant glue
You need it to bond the bug's cover and body.

Step 2: Prepare to Solder

Put the double sided tape on the desktop.

Step 3: Mount the Photo Transistor on the Tape

Mount the photo transistor on the double sided tape to the pad face to you.
PS1101W has a emitter mark (green) on the edge. The photo shows the emitter is bottom.

Step 4: Solder the Transistor to the Photo Transistor

Solder the photo transistor's collector to the transistor's collector.
Then solder the photo diode's emitter to the transistor's base.
The photo shows the soldering steps. The photo transistor's emitter is bottom side.

Step 5: Unscrew the Battery Cover

Remove the battery cover with the screw driver.

Step 6: Uncover the HEXBUG Nano

It is the first tough step. You need separate the upper mold parts (with legs) and lower cover (with motor). Cut in the back of the bug between upper mold and lower case. The two parts are bonded with instant glue.

Caution: Be careful not to cut bug's leg and your hand.

Step 7: Cut the Switch's Pin

The switch have three pins and two pins are connected. Cut the pin which is not connected, in order to avoid short circuit.

Step 8: Desolder the Red Wire From the Motor.

Desolder the red wire from the motor.

Step 9: Solder the Circuit to the Center Pin of the Switch.

Solder the transistor's collector (and the photo transistor's collector) to the switch's pin in the middle. Make sure the photo transistor face upward.

Step 10: Solder the Motor Wire to the Emitter

Solder the red motor wire to the emitter pin of the transistor.

Step 11: Tuck the Wires Away

Make the motor wires forms well to cover them.

Step 12: Cover the Hexbug

Put the cover back. Be careful to the photo transistor face to the window of the bug.

Step 13: Put Battery and Check the Action

Put the battery in and turn the switch on. Make sure the bug vibrate in light, and be silent when you cover the top window with your fingers.

Step 14: Bond Them With the Instant Glue

Make the cover and body bonded with a instant glue. Be careful not to bond the legs and the vibration motor. You may need a very little glue to bond them up.