With an output power of 1.5 W under a 12 V supply, this circuit makes use of transistors that are still common today. Power transistors must be mounted on heat sinks.
This circuit can use a pendulum sensor. We found this configuration in a 1994 publication. The...
This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are...
This circuit works both as a preamplifier and activates a relay when speaking in front of the...