Simple AC flashing power indicator ----- BLINKING POWER INDICATOR

Author: Zhang Xiaodong In various instrumentation, household appliances, household appliances, installation (or modification), using 220V communication, not only power consumption, but also beautiful, very eye-catching. working principle AC flashing indicator circuit is shown above. Here, a relaxation oscillator is smart here with the negative resistance characteristics of the crystal triplachid in the avalanche breakdown state and the charge, discharge, and cleverly constitute a relaxation oscillator. After the power is turned on, the 220V AC is converted to C. after the VD1 half-wave rectification, the R1 is currently limited, and C is charged. When the voltage of C is up to the VT of the avalanche voltage (measured about 9V), the VT suddenly subjected to a snow, and C is quickly discharged by VT, so that the light emitting diode VD2 in the discharge loop is emitted. After the discharge is over. The VT recovery is closed. The VD2 is off, and C will start charging and repeat the above process. then. The VD2 has a strong sense of enthusiasm, and the eye-catching flashing is coming. In the circuit, VT is triggered by the synchronization signal added by the base. Since the current of VT is small in the avalanche, it does not cause a permanent breakdown of VT. The circuit operating current is only 0.17mA. Therefore, the power consumption is small. Component selection The transistor Vt uses a 9013 or 3DG12 silicon NPN triode having a saturated pressure drop. The VD1 is selected for 1 N4004 or 1N4007 silicon rectifier diode; VD2 is preferably determined as needed with high brightness light emitting diodes, shapes, sizes, and colors. R1, R2 all use RTX-1 / 8W carbon film resistors. C CD11-16V electrolytic capacitor. Production and use The following figure is a printed circuit board wiring diagram. The actual size of the printed circuit board is only 40mm × 20 mm, which can be processed by the blade method. Welded boards can be used to transform ordinary alternating current indicators with hoods, or directly mounted on various instrumentation and household appliances. The flash speed can be adjusted by appropriately changing the resistance value of the resistor R1 or the capacity of the capacitor C.

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