This tester was found in a 90’s Popular Electronics. The integrated circuit is CMOS 4011. The indication is made through LED.
The circuit shown in the figure consists of a system for driving white LEDs (WLEDs) at low...
This configuration, found in many other circuits in this section, was obtained in a 1970s American...
The 4518 can be cascaded to count to values higher than 10. The output EN of this device can be...