Found in a Hands-On Electronics from the 90s, this circuit produces the dial tones of an old telephone. The integrated circuit used is uncommon today.
September 2017 - SparkFun offers through Mouser Electronics its protboard solderless board that...
April 2017 - Texas Instruments bq51222 integrated circuit for chargers and other Qi wireless power...
The circuit is from an old documentation making use of an operational amplifier of the time. The...