Modern Ultrabright LEDs white color luminescence can collect compact device for soft night lighting (Fig. 3). Since this design does not contain incandescent bulbs, she's not afraid drops, power surges and other details peculiar to devices with lamps filament.
When you turn on a nightlight in the network (via the plug HR) the supply voltage, excess which is extinguished by the capacitor C1, flows through the protective resistor R1 to diode bridge VD1. Rectified voltage is stabilized by Zener diode VD2 and is fed through resistors R3 and R4 into a chain of series-connected LEDs HL1-HL4. At the far left on the diagram the position of the slider variable resistor R3 they glow most brightly. In this mode the LEDs flows a current of 25 mA, the brightness exceeds 5500 MCD, forward voltage at each led is 3.2 V.
Since the level of illumination that is created with four LEDs, can to be excessive, reduce it a variable resistor R3, reducing the current through LEDs to 1…W mA. Resistor R2 discharges the extinguishing capacitor C1 after turn off the power.
Resistor R1 - safety non-combustible, type P1-25. You can replace the breaking import P1-7, or at least to establish a normal metal film MLT-0,5. Resistors R2, R4 - MS S1-4, S2-23, R3 AC - small wire PPB-1A or the more common SP-1, SDR-33, JS4-4. Acceptable use and resistor SDR-4, combined with switch, both groups of contacts which are connected in parallel and include rupture of one of network cables.
Capacitor - K73-17, K73-24B, K73-16 at a working voltage of at least 400 V. A special imported the capacitor is designed for operation in the chain alternating current at a voltage of 220 V, which can be found on the abundance of inscriptions on the case of, for example, CPF 250V X2.
Instead of the diode bridge CCG suitable CCA, DB104-DB107, RB154-RB157. The bridge you can collect all four diodes, for example, KD105B, CDA, KDV, CDG, 1N4004. These on the diagram LEDs Zener XA permissible to replace on DI, XA or two series-connected DA, XL, XA, 1N4738A. When using LEDs with a large work direct voltage or installing more LEDs, the Zener diode must be large voltage stabilization at 25 mA, for example, the d816a-DV. Since film capacitors have a small dispersion capacity, the selection of the resistor R4 you can establish the current through the LEDs 20…22 mA at zero resistance the resistor R3 and the network voltage of 220 V.
Details nightlight mounted in improvised housing (Fig. 4) glued from of polystyrene. Plug the block for connection to the network are removed from the defective pressovannoe molded plugs or network adaptors. On the shaft of a variable resistor, which should be trimmed, put on a handle of insulating material. If you adjust the brightness do not need variable resistor exclude.
The night light can be made more striking and bright, if in addition to white the LEDs can be connected in series with them SuperBright red Kingbright company. for example, L1503SRC/F, the brightness at a current of 20 mA up to 4000 MCD.
Attention! The design has no galvanic isolation from lighting network, so the design, establishment and operation needs to follow safety rules.
Author: A. Butov, S. CORBA Yaroslavl region