This simple circuit is perfect for an alarm. The beeper dont beep all the time but in alternance. You don't need special skills in electronics but is is recomended to know some basic electronic components to understant how it works.
The diagram is at the end of this instructable.
Step 1: Place Transistor
Step 2: Place Resistors
Place two 330 ohm resistors between the 1 kiloohm resistors, and connect them to the collector pins of each transistor and to the first line of the bread board (+).
Step 3: Add Capacitors
Step 4: Build Second Oscillator
Step 5: Add Electrolitic Capacitors
Step 6: Add Beeper and Connect to the Battery
Add the beeper liks showen in the image. Move the white cable on the image from the second bread board line to one of the collector of the thansistors of the second oscillator. The circuit is done, if you connect the power supply it will beep.
Step 7: Part List
For this beeper you need :
- 4x NPN transistors (bc547)
- 4x 1 kiloohm resistors
- 4x 330 ohm resistors
- 2x 10nF capacitors
- 2x 47uF capacitors
- 1x piezo or speaker
- 1x power source (9v)
- Breadboard with jumprers
You can use components with different values it will change the sound and frequencies but it schuld still work.