High-end step dimming light controller circuit (1)

The high-speed step- dimmer light controller introduced in this example can control the light in 4 levels: low light, medium light, strong light and off
, and also has timing control of four different times: 0 511, ih, 2h and 4h. , its circuit is just visible; 5.
    Feng Circuit mainly makes clever use of an electric fan control integrated circuit, so that the controller has
dual control functions of dimming and timing at the same time. I.C901 is a dedicated circuit for fan control. It has three wind speed output terminals:
strong wind S, medium wind M, and weak wind L. They are controlled by the wind speed selection key sS. Each time the ss terminal receives a negative pulse
trigger , the S, M, and L terminals appear low level in sequence, triggering the bidirectional thyristors VTH1, VTH2, and VTH3 to
conduct in sequence. VTH4 and its peripheral components form a bidirectional thyristor dimming circuit. If VTH1 is turned on, the positive power supply
is transferred to the capacitor C through VTH1 and RP1. Charge, C. The voltage release R is added to the bidirectional trigger diode VDH.
If the G voltage is greater than the breakdown voltage of VDH, the thyristor VTH4 is turned on and the lamp E is energized and emits light. We only need to adjust
the potentiometer RP1 to change the conduction angle of the thyristor VTH4. Usually, we can adjust RP1 to make the lamp E emit weak light
. If the thyristor vrHZ is turned on, the power supply will charge to the phase-shift capacitor (.) through VTH2 and RP2. By adjusting the potentiometer RP2, the lamp E can light up. If VTH3 is turned on, the power supply will charge to C.
through VTH3 and RP3 .
Adjust the potentiometer RP3 to make the lamp E emit strong light. The button SB2 connected to the wind speed selection terminal ss
is the light brightness selection switch. Pressing SB2 inputs a negative pulse to the ss terminal, thereby causing the output terminals S, M, and
L to output The trigger level triggers the thyristor VTH1-VTH3, so the light brightness can
be switched between low light, medium light and strong light. In the shutdown state, this key can also be used as the power-on key. The first time the power is turned on, it is in the low-light state, that is
⑩Pin L outputs a low level, VTHI is turned on, because RP1 has the largest resistance among the three potentiometers
, and the lamp E emits weak light.