September 6, 2013 /
Steve posted a detailed video showing off his entry for the 2013 Ottawa Mini-Maker Faire. A 555 Timer Chip Music Player. The beauty of the project is its simplicity.
As paper passes over individual copper plates any number of wires can drop through the holes to make contact. The length of the holes determine how long a note is played and the resistors attached to the copper plates adjust the frequency of the square wave which generates the tones. This is the perfect project for getting your kids excited about electronics. Check out the schematic and additional build photos after the break.
September 5, 2013 /
This build uses good old FSK (frequency shift keyring) technology sending 1′s and 0′s through the air. Although its applied using infra-red, the same concept is used for RF. Also Infra-red is still technically wireless (lol). So on to the build. Just in-case you want to brush up on your FSK I recommend just straight up hitting wikipedia. (If not, here’s the TLDR version; A steady pulse is used to represent a 1, and a variation in the pulse width is used to represent a 0)
On the transmitter side a 555 timer is set up as a Astable Multivibrator, the digital input (fed from say a microcontroller) pulls down the transistor which modifies the frequency of the 555 timer, causing a 0. Leaving the pin high (representing a 1) leaves the 555 timer alone. The data is transmitted via infra-red led.
On the receiver side, a 565 PLL (Phase Lock Loop) IC locks on to the frequency of the 555 timer and outputs a 1 or a 0 when the signal alternates between the 2 frequencies.
This is a great project but mostly as an educational one. Full post up on gadgetronicx.