Step #1: Circuit DesignPrevNext
- The circuit is a basic 555 timer circuit in astable mode. In this configuration the IC sends a brief pulse to the buzzer every few minutes. The values of the resistors and the capacitor determine how often the buzzer will sound and how long each pulse will be. With the values that I used, it beeps about every 6-7 minutes. (If the capacitor is completely discharged, the first beep may take up to twice as long.)
- Increasing the value of either the capacitor or the resistor between pins 7 and 8 will increase the amount of time between beeps. Increasing the value of the resistor between pins 6 and 7 will increase the length of each beep. Decreasing these values will have the opposite effect.
Step #2: Make the battery connectors.PrevNext
The only parts that you need to make are the battery connector pins. To make these, cut off two pieces of the paper clip that are about an inch long and fold each of them in half. The bent end is where they will contact with the battery. The cut ends will be soldered to the board.
Step #3: Solder the circuit to the boardPrevNext
Then solder all the components onto the board. If you are using the same PCB, you can just copy my layout. If not, just make sure to follow the schematic on Step 1 and check all the pin connections. When soldering the battery connector pins, try to align them so that they are leaning slightly towards each other. This will help make a tight connection with the batteries.