||Built on an experimentation board (Veroboard) and housed in a wooden
Microcontroller mounted in a socket to faciliate easy removal for reprogramming.
||12 V 400 mA AC/DC adapter.
||Microchip 16C84 or 16F84. Assembler for this controller is available
from Microchip free.
Many programmers with software for this controller are available. You
can buy them cheap through the internet or build yourself. I use a home
built programmer connected to and powered from the PC through a serial
Button input to start fan and set test mode. I have two of these connected
in parallell. One outside the electronics case, and one inside on the circuit
board used during development.
LED output. Once more one inside and one outside the box. It indicates
when a button press will start the fan. Every 2-minute periode there is
a 110s interval when a button press will start the fan. If you do not press
the button, the fan will start automatically at the end of the period.
Fan control output. Drives 12V 250 mA fan motor.
Magnet control output. Drives 12V 250 mA electromagnet to let one ball
into plexiglass tube.
Infrared detector input. An infrared diode transmitter and detector detects
when the ball is halfway up the tube. This information is used to stop
the fan as early as possible.