I made a variable voltage regulator and I installed 4 blue led on the top of the box in series with a 1K resistor. For indicating it is on or off but what I found is surprising for me. Idon't want to make some kind of pest control but it it was built by mistake.
Step 1: How It Works
Mosquitoes are attracted by UV light and these 4 blue leds are working like it. Just connect four 5mm blue LED in series with 1K resistor. I used 1K resistor because I am taking 19.40V from my laptop charger and its it is capable to give 3.42A. I also connected 12V dc computer power supply fan which takes 0.17A in parallel to the LED's.
Step 2: Construction
I used my Mini USB speaker case for this project. I am not going to make some kind of pest control but it it was built by mistake and it is very helpful for me. I have done some holes of 2mm in the box and put the computer power supply fan on top of it and packs all non required holes with glue gun.
Step 3: Conclusion
I left this box in a corner and in a dark place. Because i was just thinking variable voltage regulator produce lots of heat and it may explodes while continuous use of it. I was just trying the capability of my variable voltage regulator. These holes are made because to release heat which are coming from heat sink. If my variable voltage regulator is working properly in future then I will post the whole method how I built it but now within 2 days I found lots of mosquitoes in the box when it turned it.