I have been using RTL (Resistor-Transistor Logic) to build things like NOT gates, or any other types of logic. If diodes control the flow by letting electricity only flow one way, then could I use two diodes to make an OR gate, or would it interfere or disagree with my RTL?

It would be, in my mind, the two inputs have a diode each, and then the output of both is just connected on the breadboard.

  • \$\begingroup\$ Note: the reason I am wondering is mainly so I can save transistors because I have quite some diodes laying around, so I think it would be a wise idea to use what I have. \$\endgroup\$ – Cello Coder Mar 21 '15 at 16:40

Yes, in fact this is exactly what was used in the D17B guidance computer for the original Minuteman I missile:

"The D-17B contains 1,521 transistors, 6,282 diodes, 1,116 capacitors, and 504 resistors.

The design specifications of the D-17B required very high reliability. This was achieved by using DRL (diode-resistor) logic extensively and only using DTL (diode-transistor) logic where gain or inversion was required in this fully solid-state computer. In the early 1960s when the D-17B was designed, transistors were not as reliable as they are now, thus the designers used transistors only when necessary."

DL (Diode Logic) aka DRL (Diode Resistor Logic) can be used to create various logic gates such as AND, OR, OR-AND and AND-OR, but because it is made of of only passive components, the signal degrades fairly rapidly (due to the diodes, you lose 0.7v of signal for each stage). Also, due to the lack of an active element, it cannot perform inversion (so gates like NAND and NOR are not possible). Therefore, for any but the most tirivial circuits, they must be followed by a DTL (Diode Transistor Logic) or other active stage including one or more transistors.

  • \$\begingroup\$ Thanks! I am going to test it, just didn't want to mess up the transistors or diodes I do have, as I don't have that many as of now, and am itching to do something with them while I wait as I order some more. Again, thanks! \$\endgroup\$ – Cello Coder Mar 21 '15 at 17:16

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