Basically a counter circuit activates a sequence of outputs or relays one at a time, through a clock signal generated by a timer (for example NE555) or manually sent. In this article I’ m talking about two counter circuits (4 stages) that I created just for fun. The first one is based on relay logic, while the second one uses logic gates (without CD4017 or similar).
Relay logic counter
This circuit consists of a sequence of 4 relays activated one at a time by a clock signal, in other words a one-directional counter. The logic is repetitive, so it can work for more relays. Once the circuit is supplied no relay works, except the clock relays (K, K1).
By pressing the button for about one second the cycle starts and repeats. Each relay is activated by an impulse of K (3-11) , but almost at the same time K1(1-9) opens. For that reason a 22uF capacitor is required. I used the diodes in order to prevent current back-flows, that would activate the relays in a missed sequence.
This counter works fine with a pause of 1 second or more. If the time is shorter the clock relays may be stressed.
Logic gates counter
The operation of this circuit is similar to a CD4017 counter, but it uses AND, OR and NOT logic gates. The clock signal is manually sent. Once you supply the circuit the first stage turns on. Each of the gates number 1, 3, 5 and 7 switches on if the previous stage and the clock signal are both on.
The gates number 9, 10, 11 and 12 are supposed to prevent all outputs from being triggered at the same time. Each of these gates turns on if the previous stage is activated before the clock signal.