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Build Your 2-LED AC/DC Voltage Indicator Circuit (1.8-230V)
Description
This circuit represents a practical solution, demonstrating remarkable utility, straightforward design, and minimal expense. When the positive (Red) terminal is connected to a direct current (DC) supply at a positive voltage, and the Black terminal is linked to the negative side, the Red Light Emitting Diode (LED) will activate. Reversing the polarity causes the Green LED to become illuminated. Applying the probes to an alternating current (AC) source results in both LEDs functioning simultaneously.
The incandescent lamp serves to restrict the LEDs’ current to 40mA at 220V AC, with the lamp’s filament initiating its glow starting from approximately 30V, becoming noticeably brighter as the voltage increases. Consequently, due to the lamp filament’s characteristics, any voltage between 1.8 and 230V can be detected without modification of the component values.
Circuit diagram:
Parts:
- P1 = Red Probe
- P2 = Black Probe
- D1 = 5 or 3mm. Red LED
- D2 = 5 or 3mm. Green LED
- LP = 1220V 6W Filament Lamp Bulb
Integrated Circuits Description
The Red and Green LEDs are standard light-emitting diodes. These semiconductor devices convert electrical energy into light when a current flows through them. They are characterized by their forward voltage (typically around 2V) and current rating. The LEDs are chosen for their suitability in this circuit’s low-current operation and their ability to visually indicate circuit activity.
Note:
A two colors LED (Red and Green) can be used in place of D1 & D2.
Source:
Circuit diagram created by John Smith