This project is for fun but not only : It is mostly a DIY gift for christmas !
It needs to be funny but not too ugly.
The idea is simple : Make a "don't touch the wire" game in the form of a cow.
The head of the cow is made with the non-insulated wire that you don't want to touch,
And the tail forms the hook you need to pass through.
The body contains the electronic stuff including a battery.
To make it a bit special the cow will react several ways
1- with light: Cow's eyes lit
2- with sound: Cow moos (of course)
3- with touch: Hook vibrates !
The project is made with maximum of reuse components :
- 50cm of single core electrical wire,
- a 3.7v lithium battery from a broken toy,
- a speaker and vibrating motor from an old phone,
- some twisted wires from an old desktop computer.
- an Arduino pro mini 3.3v and some basic components from the drawer
- and last but not least: a beautiful sardine can !
I have to warn that sound has very poor quality and only two moo audio samples already takes all program memory. So you may not build your DIY MP3 player with this but it is surprisingly suitable for this project.
The S9014 NPN transistor as shown on schematic (see project gallery) enable to increase the volume a bit. This transistor has higher gain than classical S8050 or 2N2222.
Vibrating drive is made considering the vibrating motor as a small motor, which it is as far as I know. It is possible to modulate vibration intensity using pwm. For this project, we have a better surprising effect on the player with a simple all-or-none drive.
The device is battery powered. So the autonomy is optimized using LowPower library from LowPowerLab. The hook is connected to pin 2 (through a transitor), on which we attach a wake up interrupt before powering down the device. So basically, the device is always sleeping. It wakes only when the wire is touched, plays the sound, vibrates and go back to sleep.