This well-known circuit version of the siren was obtained in a Colectro Handbook from the 70s. The transistors are of general use, with Q2 being a BD136 for greater power with power from 6 to 12 V.
This circuit was found in American documentation from the 60's. The transistors are made of...
This divider by 8 is synchronized because it is implemented based on TTL or CMOS logic according to the...
This circuit causes the LED to flash at a frequency determined by the capacitor and resistor...