Narrow pulse infrared light emission circuit

A multivibrator is composed of a time base integrated circuit 555, a transistor VT and a small number of peripheral components. The charge and discharge
time constants of the circuit are Ti and five, where Ti = 0.7 (碡 + RP) island, T2 -
0.7RPCz, and its oscillation The frequency depends on the charge and discharge time constant T (T=
Ti+hole), that is.
    _, i-l/ Ding 1. d4／[(Rl+2RP)(12] Use
    the potentiometer RP Hr to adjust the oscillation frequency of the circuit as needed. As
shown in the parameters in Network 18-54, the oscillation frequency is about 20kHz. Due to the charging
time constant (Ri+ RP ) (is much larger than the discharge time constant R2 C2. Therefore,
the time ratio of the low level and the high level of the oscillation pulse output by the ③ pin is about
1: 10. Since the driver stage VT uses the NPN transistor 3DG6, the infrared emitter
The time ratio between when the photodiode is on and off is 1 t 10. That is,
the time the infrared emitting tube emits infrared light is only 1/10 of the oscillation period T, and it emits narrow pulse infrared light.
    Infrared light emitting diode LED Using TLN107 type diode, its peak current can reach 600rnA, and the average level is about 250mA.
There is a lens on the top of the LED, which can condense the emitted infrared light into an infrared beam with a radiation angle of 50. ~ 60. and radiate outward.
Sent to the receiver as an infrared signal .