Here’s a fun project to make with the 555 chip.
Here’s how it works. When it’s turned on by pressing SW1, the 555 astable oscillator is activated. It will produce a tone through the speaker that can be varied in pitch by changing the distance between the LED and the photo cell. The photo cell is mounted at one end of a 1/4″ diameter tube which shields it from 99% of the light. The LED is mounted on a piece of music wire and inserted into the tube. You change pitch by simply moving the wire in and out. Move it inwards and get a higher frequency tone. Move it outwards and the tone goes down in frequency. You can build the device as I have shown in the pictures and video, or get creative and come up with something new!
I encourage you to try building other circuits with the 555. It’s a very versatile chip with many applications.
Have fun and…
Keep On Hackin!
Parts list:
2 – 100 Ohm ohm resistors
1 – Photo Cell also call Light Dependent Resistor (LDR)
1 – 2.2 mF Electrolytic capacitor
1 – 100 mF Electrolytic capacitor
1 – Bright white LED
1 – LM555 8 pin DIP timer chip
1 – Small speaker
1 – Momentary push button switch
1 – 9 volt battery
1 – 9 volt battery clip
1 – small perf board to mount components on
Hook up wire
5″ length of music wire or large paper clip.
Rob Paisley’s 555 timer circuit page.
This has a TON of great info on the 555 including a few timing calculators to aid in component selection.
http://home.cogeco.ca/~rpaisley4/LM555.html
