A trigger is a digital device capable of storing one bit of information. In particular, so-called RS-triggers are quite common. They are used in small static RAM, when the dimensions of one cell are not critical, for example, in the CMOS memory of settings on the computer motherboard.
Instructions
Step 1
Take a microcircuit that contains at least two 2I-NOT logic gates. This can be, in particular, K155LA3 or K561LA7. Both of them contain four such elements, and therefore up to two RS-triggers can be assembled on any of them. But the second microcircuit is better to use, since it consumes significantly less power.
Step 2
Connect the output of one of the gates to one of the inputs of the other. Do the same with respect to the output of the second logical element. If you did everything correctly, the elements will be connected to each other "crosswise", and each of them will have one free entrance. Do not forget to apply power to the microcircuit (its parameters and the method of connecting the source depend on the type of microcircuit).
Step 3
Since the elements are equivalent to each other, conventionally call one of them "upper", the other - "lower". Now, when the output of the first of them is a logical unit, and the output of the second is zero, we can assume that the trigger itself is set to the state of unity, and with the opposite combination - to the state of zero.
Step 4
To set the trigger to the state of a logical one, feed zero to the free input of the upper element, and one to the lower one (remember that not AND elements are used, but NAND elements). To set the trigger to zero, do the opposite.
Step 5
But the main property of the RS-trigger, for the sake of which it is used, is the ability to maintain a given state after removing the control action. Apply units to both inputs, and the trigger will remain in the state in which it was before.
Step 6
Do not apply logical zeros to both inputs of the RS-flip-flop - in this case, it will not remember the previous state, and ones will appear at both of its outputs. From the point of view of binary logic, such a state is considered meaningless.
Step 7
In addition to the memory device, the RS flip-flop can also be used in bounce suppression circuitry. In this case, apply a logic high to both of its inputs through pull-up resistors. Connect a toggle button to the trigger, which alternately connects to ground one or the other of its inputs.
