How to make a HEXBUG nano to be activated by light.

Picture of 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.

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Step 1: What you need

Picture of 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.

3. Photo diode
I used PS1101W.

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

Picture of Prepare to solder
Put the double sided tape on the desktop.

Step 3: Mount the photo transistor on the tape

Picture of 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

Picture of 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

Picture of Unscrew the battery cover
Remove the battery cover with the screw driver.
ipalffy2 years ago
Thanks for your reply.
Since then I tried two tranzistors:
BC 817-40
KP-2012P3C (phototranzistor)
The bug is sleeping well but it need more light to wake up.
And unfortunatelly it is slower.
I am thinking about to change the battery to 3.0V
Best Regards,
ipalffy2 years ago
Dear longjie!
In Europe I don't able to by a PS1101W phototranzistor.
Please give me an advice which parameters did you search to this project.
Which parameter of the phototranzistor is important for the right functioning.
Thank you for your help!
Best regards,
longjie0723 (author)  ipalffy2 years ago

I'm mot sure. I guess most photodiode will work.
The size of the chip may be matter when you build.


This is so awesome !!! You managed to do that is such little space !!!! I just made a modular vibrating robot here, so you could use bigger electronics :

awesome man....i want to make one.......btw one of the hexbugs was squashed like a bug^^hehe
GrandeSwag3 years ago
I love hexbugs!
longjie0723 (author)  GrandeSwag3 years ago
mee too!
Kiteman3 years ago
Wow, that's a really neat hack.

Does the toggle switch still work (to save the battery between tricks)?
longjie0723 (author)  Kiteman3 years ago
Of course yes! Oh, sorry I forget to attach schematics.
I see it now - good job.
longjie0723 (author)  Kiteman3 years ago
Thank you!