Description:
The dimming circuit can make the voltage at both ends of the bulb change in the range of tens to 200 volts, and the dimming effect is remarkable. In the circuit, R2, R3, R4, RP1, C1 and VT1 constitute a single junction transistor oscillator circuit, which is used to generate trigger pulses.When the capacitor is charged by R4 and RP1, the voltage Ue increases gradually. When the Ue reaches the peak voltage, e B1 turns on and the voltage on the capacitor outputs a pulse voltage to R2 via e-b1. Because the resistance of R4 and RP1 is large, when the voltage on capacitor drops to the trough voltage, the current supplied by R4 and RP1 is less than the trough current, which can not meet the conduction requirements, so the single-junction transistor restores the blocking state. Thereafter, the capacitor recharges and repeats the above process. As a result, a sawtooth wavy voltage is formed on the capacitor and a pulse voltage is formed on R2. During each half cycle of AC voltage, the single-junction transistor will output this pulse to trigger the gate of the thyristor, which will turn on the thyristor and light up the lamp. Change the resistance value of RP1, that is, change the oscillation frequency of sawtooth wave, thus change the size of thyristor conduction angle, and then change the output voltage of controlled rectifier circuit to achieve the purpose of adjusting the brightness of the bulb.
Input voltage: 220V
Size: 45 x 30mm
Package Included:
10 x DIY BT33 Table Lamp Dimmable Optical Circuit Kit
