|Nov. 22, 2007|
|The buzzer timer is built into a used computer speaker case. Pre-existing
circuits from the speaker amplifier were retained. The timer operates as
More comments have been added to the file buzzer_timer.c
unused files (com.c and com.h) have been removed from the zip file.
Schematic of circuits added to computer speaker to create the Buzzer
|Nov. 20, 2007|
|The buzzer itself was completed today. I don't have a lot of time to
update this page at the moment. When I get a chance I will add more information
about the circuit and operation instructions.
It looks like this. The AC-DC adapter is rated at 9 Vdc 800 mA.
Note that there is an on off switch on the front and a volume control. It seems that the Buzz Now button needs to be pressed harder than the others.
The switches and label look like this close up (the flash washed it
out a bit).
The code for the PIC inside is contained in this zip file.
|Nov. 9, 2007|
|A computer speaker will be hacked into a 5 second -- 10 second timer
buzzer for one of the science challenge events for 2007.
This image shows the circuit board from the computer speaker. Connection
points are shown.
A custom PIC18F4525 microcontroller board is being prepared to fit into the battery compartment of the computer speaker. The PIC18F4525 microcontroller will be programmed in C language to respond to button switch inputs and it will also create the signal that will be amplified and fed to the speaker. The Pins along the top of the board will be used to program the microcontroller in circuit.
The image below shows the solder side of the PIC18F4525 custom board.
Downloading first test program
Waveform for Buzzer
from the following program
Next I will work on the logic for the switches.