POSC = Pocket Oscillator

Description :
-------------

It's a gadget producing funny sounds. I built it for my son.
Original design was done by sonodrome (https://www.sonodrome.co.uk/)
Here a demo of a genuine unit :
https://www.youtube.com/watch?v=R5Wg0e9xl_A&ab_channel=sonodrome

How it works :
--------------

Two NE555 ICs mounted as astable multivibrator, first is activated via a touch
sensor, and drive the second. Second's 555 time constant is modulated via a
simple photoresistor. Output is forwarded to a speaker via a NPN transistor.
Note that this design use a specific 50 ohm speaker

Implementation :
----------------

I used an enclosure with a 9V battery location, manufactured by a german
compagny :
https://www.kemo-electronic.de/en/Components/Cases/Closed/G01B-9-V-DC-Plastic-case-small-approx-102-x-61-x-26-mm.php
It can be found here :
https://fr.farnell.com/en-FR/kemo-electronic/g01b/case-plastic-black-battery-comp/dp/3389929

Touch sensor can be done via two closely spaced electrical conductor. Be careful
because if it's not enougth spaced, it will not work properly. Note thats other
designs use an other photoresistor for the first 555.

My son select a purple led for poweron indicator and a "gold" one for oscilation
founded on AliExpress.

Enjoy!