Guitar Effects Controller—Hank Wallace, Fincastle, Virginia
Hank is both an avid guitar player and an electronics addict. With this project, he’s able to bring both his hobbies together.
The problem: when playing live, one of the most frustrating tasks for guitarists is controlling their sound. Typically, the problem is solved by placing an array of foot switches on the stage. But, that restricts the player to one spot—an unacceptable constraint for rock and roll.
Instead, Hank mounted three inexpensive aluminum-tape pads to the pick guard. A small transmitter under the guitar’s phone jack senses touches on the three metal pads. A transmission is triggered by the resistance of the body from the pad to ground.
Notably, the "ground" of the transmitter is actually the VCC of the microprocessor since the reference for the pads is not ground, but the +3-V supply of the transmitter. While this may sound like a problem, it’s really not since the output of the transmitter is AC coupled to the guitar audio path.
So, as the guitarist touches a pad, the contact conducts enough current to turn the transistor on and awaken the PIC12C508. After a 120-ms debounce delay, the processor qualifies the three inputs, produces a 50-kHz pulse train, and then sends it along the guitar cable to the receiver mounted inside a commercial DSP-based guitar-effects processor.
The receiver decodes the databurst, determines which key pads were activated, and then connects one or more foot-switch terminals in the processor to ground for 250 ms, thereby simulating the foot-switch operation.
Second Place $2000
Internet Appliance—Myron
Loewen, Niverville, Canada
Lots of companies today like to boast about having the smallest Internet server, and while theirs are impressive, Myron puts all them all to shame.
With an 8-pin PIC12C672, Myron handles all the tasks of dialing an Internet service provider, negotiating PPP configuration and compression options, negotiating IP configuration options, authenticating itself with PAP, finding its IP address, implementing PING protocol, and implementing TFTP protocol. Sound like too much?
On the hardware end of things, the only real difficulties came in determining which port to use for which functions so that the number of analog inputs was maximized.
And in the software department, you’ll find a lean-mean state machine. As packets arrive, they are examined to see if a replay or state change is required. And, if nothing arrives within a set amount of time, each state has its own job to do.
Third Place $1000, $500 for using PIC12C508
R/C Brakes—Greg Mrozek, New
Hope, Minnesota
Even when racing radio-control cars, you can’t forget to use the turning signal. And, woe betide the car that tailgates if your brake lights aren’t up to snuff.
But, Greg fixes all that with R/C Brakes, a brake light and/or turn-signal controller for radio control cars. The device takes input and power from the servo outputs of a standard radio-control receiver and uses these signals to control the brake lights and turn signals mounted on the body of a radio-control car.
The RX signal from the servos is normally low with a high-going pulse length of 0.8–2.1 ms. A software capture algorithm captures this pulse width and then uses the information to control the tail lamps.
R/C Brakes is completely configurable, enabling it to operate correctly on almost any R/C car. You can program the device through a single push button and the configuration data is stored in a serial EEPROM.
