Roadblock flashing warning light circuit (2)

The roadblock flashing warning light is composed of Y976 alarm integrated circuit. In the picture. VD1,
VD2, vs, (1_ and Cv, etc. form a simple capacitor step-down half-wave rectification and voltage stabilizing circuit, which outputs
a DC voltage of about 5V for Y976. RP1, photoresistor R1 and integrated block ⑤ The pins form a light circuit,
RI during the day. It shows low resistance when exposed to light, so the enable end of Y976, i.e. pin 5, is low level, Y976 does not
operate. VTH is turned off, and the warning light E
is small. When night comes , JtI.
It is high resistance when exposed to no light.
The ⑤ pin of Y976 is commercial power A. The ① pin
outputs a square wave pulse -shaped alarm sound
signal through R. The Ⅱ takes
the gate of the thyristor VTH to open the VTII
gap and cut off, the "light E"
will flicker and glow.
    Adjusting RJrJ1 can change the light control sensitivity of the circuit, so that the circuit will flicker and glow under the illumination that needs to alarm . Adjust RP2 to change the resistance of the external oscillation resistor
of the integrated block . Therefore, the frequency of the integrated block's output flI pulse can be changed , that is, the flashing frequency of the warning light E can be changed.     VTH can use small plastic bidirectional thyristors such as MAL94A4. E is a red incandescent bulb below LOUW. (,, requires the use of (, BB 400V type Polypropylene capacitors, no special requirements for other components.