View Full Version : How can AND gate replaced by series switches
yungsoft
Mar 14, 2011, 12:02 PM
jcaron2
Mar 14, 2011, 08:26 PM
Hook one end of the circuit to a voltage source, then put two (or more) switches in series, and then shunt the other end to ground through a large resistor. That node between the switches and the resistor will be the output of the AND function. The output potential will be ground (0 volts) unless ALL of the switches are closed. Hence, the output implements the AND function.
For what it's worth, you could implement an OR function but putting the switches in parallel with each other.
Stratmando
Mar 15, 2011, 12:20 PM
A NAND would be like above, but the output is inverted, If switch 1 AND 2 were on, the output would be Off.
jcaron2
Mar 15, 2011, 01:10 PM
A NAND would be like above, but the output is inverted, If switch 1 AND 2 were on, the output would be Off.
No. Maybe I didn't do a very good job of explaining what I meant. When both switches are on (closed), the output node is connected directly to the voltage at the far side. Meanwhile, the output node is separated from ground by a large resistor. When either (or both) of the switches is off (open), however, the output node is separated from the voltage supply by an open circuit. Therefore, the resistor pulls the output to ground.
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