Two LEDs with different color (e.g., red and green), you can build a simple indicator for voltages from 4.5 to 220 V. It is also able to determine the polarity of the source in the range 8-220 V. When measuring AC voltage, both diode glow, but if it is constant — lights one of them depending on the wiring polarity indicator. The scheme proposed by the Czechoslovak journal “Amaterske Radio”.
Measure the mains voltage from 110 to 220 In a short-term need. a current-limiting resistor R1 (see Fig.). In addition to the household, the indicator is used and motorists.
Czech 1NZ70 Zener can be replaced with a tense domestic stabilization 5-6 In, for example Д815А, the diodes V1 and V5 — any low-power silicon, for example D226. LEDs can be АЛ102Б (red) and AL 102V (green).
Recommend to read
VELCRO
It is easy and convenient to clean the floor in the Studio or room with any ordinary MOP, the "dressed" Terry cloth Velcro.
FLYWHEEL ELEVATOR
In the halls of the Central exhibition NTTM, dedicated to the XXVI Congress of the CPSU, it is possible to see many original designs and arrangements, created by young scientists,...
