This is a Japanese commercial radio from the 60s. The superheterodyne circuit of 7 transistors for medium waves has 200mW of output when powered by 4 common batteries.
This 2001 CMOS digital circuit draws numbers from 00 to 99 and can be expanded. However, it does...
This filter was found in an old publication from 1977. The circuit must use a simple two-voltage source...
This circuit beeps when the sensor is triggered by the opening of the freezer door or other...