Single touch light switch circuit (2)

A single-button touch light switch composed of a voice-activated integrated circuit
can also complete the operation of turning on and off the light using only one electrode piece M. The circuit wiring also adopts two-wire system, which can directly replace ordinary mechanical switches
.
    Japanese tube VT2 and diodes VDl - VD4 form an independent circuit, and the control circuit
is composed of BH-SK-I voice-activated integrated circuit, transistor VT1, etc. When the gate tube VT2 is in the off state, the switch is in the off state
and the light E is on. At this time, there is
weak alternating current passing through the lamp F, VD1
~ VD4 bridge rectifier, N. Buck
current limit, vs regulator and C.
Filter and output about 6V DC
voltage for the control loop. The Lu
control integrated circuit is connected into a classic
bistable circuit, and the trigger
pin ① is connected by R. with R. Voltage-divided feed, R. The resistance is slightly smaller than R. , so that the ① pin iL level is slightly higher than 1 72Vrji), so that the circuit
has a higher trigger sensitivity. At this time, when someone touches the electronic chip M with his hand, the AC signal induced by the human body
is j?. Turning on pin ① causes the steady-state flip-flop inside the integrated block to flip, and the output pin ⑥
changes from the original high level to a low level . The diode VT1 is cut off, and the gate tube VT2 is turned off by R. When the trigger current is obtained and turned on, the lamp F
lights up and emits light. After the lamp F is lit, the 220v AC voltage will drop at both ends of the lamp.
Although drops, there is still a voltage drop of 2V. After filtering by R: and (1:, it can still Outputs a DC voltage of about 2V
, so the integrated block J{fI SK l can still work normally. At this time, if the M human body induction signal is touched again, the trigger terminal ① pin is input
again , causing the integrated internal product steady-state trigger to flip again. , the output terminal @ pin
changes from low voltage to high level, and the transistor VT1 is turned on, forcing the thyristor VT2 f J pole to drop to a low level . The transistor wr2
is turned off when the alternating current crosses zero due to loss of trigger current. Light E goes out.