Mosquito Repellent

The summer this year is too hot, the heat is not really a problem but mosquitoes ...! ,especially i camping.

So after i tried some solutions i got the idea to make an electronic mosquito repellent that i can take with me wherever i go. this circuit is just a transistor multivibrator that generates high frequency sound ,and mosquitoes don't like this sound.

I am not gonna use a PCB i will just solder components together to make it a simple and cheap

Update : here is the Kicad project + (the PCB , the schematic , the components view ) in PDF

Mosquito repellent.rar

1. two BC548 transistors or equivalent
2. two 100k resistors radio shack link
3. two 1.5k resistors radio shack link
4. one 4.7k resistor radio shack link
5. one 2nF ceramic capacitor radio shack link
6. one 560pF capacitor radio shack link
7. 5mm Red led radio shack link
8. Toggle switch radio shack link
9. 9v battery radio shack link
10. 9v battery snap connector radio shack link
11. Piezo element radio shack link
12. a small project enclosure radio shack link
13. some wire

This components i salvaged them from my older projects ,but i put links to Radio Sack

1. Cutting plier
2. Needle nose plier
3. Solder iron
4. Some solder
5. Philips screwdriver
6. Hot or super glue

solder the components in order like in the pictures

1. Bend the collector and base pin of each transistor
2. Solder the emitter pins together
3. Solder the 560 capacitor then 2nf one solder the two 100k resistances then the other 1.5k
4. bend the free pins of 4 resistance and so

1. Make a hole for the toggle switch with the soldering iron then enlarge with the screwdriver
2. Screw the switch in place

1. Solder the 4.7 resistor to the positive pin of the led
2. Make a side hole on the box with the soldering iron for the led
3. Solder the led current limiting resistance to one one switch pin

1. Solder two wires to the Piezo element ,positive pin is the middle disk
2. Make a small hole on the lop next to the switch for the Piezo element wires
3. Insert the wires in the hole and glue the Piezo element to the top

1. Solder the red wire of the snap connector to the other pin of the toggle switch
2. Solder the black wire to the negative pin of the LED

1. Solder the common pin of the resistors to the pin of the toggle where the led limiting resistance is soldered
2. Solder a wire from the emitters to the negative pin of the led
3. Now solder the two piezo element wires ,between the positive and the 2nf capacitor junction with the collector

First testing:

1. Connect the 9v battery
2. Turn on the switch , the led should light
3. If you don't hear nothing put in parallel a capacitor approx 100nf with the 560pf capacitor ,if you hear a buzz everything is alright ,you're just not sensible to the high frequency
4. Put the battery in place and close the box

final word:

If you are sensible to the high frequency this can drives you nuts