Alarm for parallel sensors (CB6416E)

This circuit was obtained from a Popular Electronics of the 90s. The SCR is of any type and the number of sensors is unlimited.

1 500 000 gain Amplifier (CB6641E)
We found this circuit with transistors in a Philips documentation from 1968. The double transistor...
Shunt Motor Control (CB4250E)
This circuit, from the ON Semiconductor Thyristor Manual, controls both the speed and direction of...
Light On Car Alarm (CB1421E)
This circuit was found in a 1978 American publication. It beeps if the car's lights are on and the...