We found this circuit that can reach 50 MHz in the February 1997 Electronics Now magazine. The integrated circuits used are not very common today.
If the input voltage falls below 12 V the LED glows up. Other voltages can be monitored by...
This motor control using transistors was found in a recent English publication. The circuit is for...
In the figure we have an electronic toy organ that can both serve to amuse children as a basis for...