Two-level neon signaling device. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Indicators, sensors, detectors
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In network devices, a light signaling device is often used, consisting of a neon lamp and a current-limiting resistor. Such a signaling device is usually turned on at the input of the device or after the switch. But in the first case, the lamp indicates the presence of mains voltage, regardless of the position of the power switch, in the second case, when it is closed.
A signaling device with two gradations of brightness of the lamp glow is more informative (the lower glow of the lamp corresponds to the open position of the switch, the larger glow corresponds to the closed position). This allows not only to determine the operating position of the switch, but also to find the device connected to the network in the dark. One of these schemes is shown in Fig.1.
When the SA1 power switch is open, the mains voltage is supplied to the HL1 lamp through the resistor R1, the VD1 diode and the load. The R2VD2 circuit practically does not shunt a neon lamp. When the power switch is closed, the HL1 lamp is powered through the elements R2, VD2, and the R1VD1 circuit, being connected in parallel to the neon lamp, does not shunt it. Since the value of the resistor R2 is several times less than that of R1, the neon lamp in the second mode shines brighter.
A feature of the circuit shown in Fig. 2 is that when the SA1 switch is open, the neon lamp is powered by a half-wave voltage through the R1VD1 circuit, and when the switch is on, it is fed by a full-wave voltage through both circuits (R1VD1 and R2VD2), so the neon lamp flashes brighter. The circuit can be simplified by removing the diodes and slightly changing the resistance of the resistors.
If the device has a paired mains switch that opens both power wires, then the circuit becomes simpler (Fig. 3). Here, the different brightness of the glow of a neon lamp is provided by turning it on through resistors of different ratings.
Very convenient indicator with two neon lamps. The device, the circuit of which is shown in Fig. 4, is intended for use with a single-pole switch. When the switch is open, the neon lamp HL1 shines, the circuit of which is closed through the resistor R1 and the load. When SA1 is closed, the neon lamp HL1 goes out, and HL2 lights up.
In devices with two-pole switches (Fig. 5), such a signaling device can be assembled differently. When the switch is open, the neon lamp HL1 shines, which is powered through the resistor R1. When the switch is turned on, a parallel connection of neon lamps is formed, while one of them goes out. It is necessary to choose the lamps so that HL1 goes out.
Details. Any diodes with a reverse voltage of at least 300 V (D226B, KD102B, etc.). Resistors type MLT-0,25. In the case of using neon lamps from starters and other devices, the resistor values \uXNUMXb\uXNUMXbmay be different.
Author: R. Kushchik
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