I should have clarified better, i meant a diy sensor to measure air pressure, like the HX710B does. i was thinking of something like the coiled party whistles that unfurl when blown, but they don ...

The sensor will be installed at the main power supply, which is conmected to 40 to 50 lights," he explains. He makes a device for Rs 3,200 and sells it for Rs 3,800. With this LDR system, villages ...