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The scheme of the device from mosquitoes and midges

The adjustment is reduced to the choice of the frequency range of the generation, which is set by changing the capacitance C1 and the resistance R 3. The range is 1-1.5 meters.

VT1 - MP36 - MP38.
R1-СПЗ-б, СПО 100кОм
R2. -100k ohm
R 3. -10 kOhm C1. - 3300 uF
IN 1. tel. capsule:
TD-6, DEM-4m;
Dynamic head
0.1 GD-6: 0.025 GD-