The TAA300 integrated circuit is not common today. In fact, the circuit shown is from a Dutch Philips documentation from 1969. The output is 8 ohm speaker and 9 V power supply.
Approaching the hand or an object to the sensor of this circuit, the relay closes its contacts. The...
We can use the trigger point of 555 to detect voltage levels or thresholds, in a circuit as shown...
We found this circuit in a 90's EDN. The circuit is based on a control integrated that is still...