I built this up for quickly testing 555 timers, 4013 dual flip-flops, 4066 analogue switches and almost any quad op-amp a few years ago, I thought I'd share it here...
The 555 timers is set up as an astable. It's output blinks D2 at about 4 Hz. These pulses are used to test all the other chips, so a working 555 must always be inserted into the board.
To test the 4013, the clock pulses enter the Clock input of the first flip-flop at pin 3, Feeding the notQ output on pin 2 back to the data pin 5, results is the frequency being divided by 2. This is shown on D3. These f/2 pulses are then sent to the second flip-flop, which is configured in the same manner, the resultant output is displayed on D1, and is f/4.
In testing the 4066 switch, the pulses are fed to the switch input of all 4 quad switches. The inputs and outputs can be reversed, by reversing the polarity of the input and output between 5V. The practical upshot is the one set of LEDs should flash in time with the pulses from the 55. Flicking the switch, reverses the in's and out's, and the other set of LED will flash.
The op-amp is set up as a comparator, and all LEDs flash in time with pulses from the 555, although slightly dimmer than the other LEDs.
Here it is in action.
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