Switches controlled by the duration of the input control signal
Among the switches of various kinds of loads, the circuit of the switch is of particular interest, controlled by varying signal duration. So, for example, feeding a short pulse to the input will turn on the load, and a longer pulse will turn it off. Such an impulse can also be given by pressing the control button.
Figure 1 shows an example of the implementation of a switch operating according to the principle described above. A short input signal switches the state of the device, and a voltage appears at its output, approximately corresponding to the supply voltage, for example, 10 V. A memory element is made on elements U1.1 and U1.2 of the CD4001 chip. If a longer pulse is applied to the input of the device, the capacitor C1 will charge through the resistor R2. The transistor Q1 2N7000 will open, shunting the input of the element U1.1, and will switch the memory element U1.1 and U1.2. At the output of the device, the voltage will drop to zero, the load will turn off.
Figure 1 A switch controlled by the duration of the input control signal.
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The second version of such a device is shown in Figure 2. It works on the same principle and contains a voltage repeater on the U1.1 element of the CD4050 chip as a memory element.
Figure 2 A variant of the switch circuit that contains a voltage repeater on the U1.1 element of the CD4050 chip.
Michael A. Shustov is a doctor of technical sciences, candidate of chemical sciences and the author of over 800 printed works in the field of electronics, chemistry, physics, geology, medicine, and history.
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