This interesting circuit for the RDA8851 allows you to obtain two volumes with a simple touch. The circuit is from an Electronics Now from December 1988. Note the amplifier voltages.
This circuit is from a Radio Electronics magazine from February 1962. It makes use of an old...
Microchip's MCP6411 Operational Amplifier can operate at voltages of 1.7 V and has a quiescent...
This circuit powers a small 5 W lamp that goes out when power is lost. The circuit can use the...