AND and OR gate?

Question

With which diodes can i realize the AND gate and the OR gate (like diodes 1N4007, 1N4148) and with which foemuls can I define the value of the resistors?

Answer 1

I have used 1N4148 diodes. The 1N4007 is a general purpose rectifier and is slower than the 1N4148 -- which is used for fast switching applications (like making diode-logic-gates).

You can make a crude 2-input AND gate out of 2 diodes and a resistor. The resistor can be anywhere between 2 kOhms to 5 kOhms, depending on what the output is driving.

Here is an example circuit:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/diodgate.html

You can also take the OR circuit and instead of a pull*down* resistor to ground, make it a pull*up* resistor to Vcc and it becomes an AND gate.

I just had to kludge one of those on my latest project, because the software guy wanted some extra decoded address spaces -- not in the original spec.

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