An other rain sensor, it consists of the typical rain sensor with the line shaped PCB where the rain falls, a microphone per-amplifier, an amplifier, a VU meter and a power supply to drive all the above.
The idea is simple, lets say you have no access to weather conditions but you want to know if it is raining. Not only that, but you would like to be aware on how strong the rain is
You can watch a video here:
The rain sensor will become active at the presence of water drops. with the use of a relay then all other circuits will be powered.
Following, a microphone per-amplifier located under a reversed stainless steel bowl (acts like a bell), collects the sound of the rain drops. The amplifier multiply the signal from the per-amplifier and drive the VU meter where must be visible and most likely indoors, near you.
If it drizzle, some leds will light up but not all. If the rain is strong enough then all the leds will light up and with greater frequency. So, using this method one can have an idea on rain conditions.
This instructable is for one (1) set of pre-amp + amplifier + VU meter.