Ice Warning on the Track (CB6046E)

We found this circuit in an 80's Radio Electronics. The circuit uses a PTC sensor and an LED indicator. The power comes from the car's own battery.

Shadow Relay (CB3867E)
When light fails to focus on the sensor, a common photo-transistor, the relay closes its contacts....
Regulator with the SG1524 (CB5454E)
The component used in this regulator is not common today. The switching circuit is from an 80's...
Switched Positive Regulator 723 (CB5462E)
The basis of this circuit is the 723 integrated circuit, not very common today. We obtained this...