RTL Logic Gate help - 2x In OR / 3x In XOR

[juz_ad]

Hello,

I'm looking to build a 2x input OR Gate and a 3x input XOR Gate using Resistor/(NPN)Transistor Logic.

I have this schem of a 3x Input NOR: https://en.wikipedia.org/wiki/File:RTL_3-Input_NOR_Gate.svg

1) From that schem, if I remove 1x Input and either Invert the output or take the Q Output from the joined Emitters (hmmm - not so sure about that option now...) - does that give me a 2x Input OR?

2) Is a 3x Input NOR the same as an XNOR? i.e. If I invert the output of that schem I get a 3x Input XOR from that XNOR? The truth tables suggest not - but I'm asking anyway.

If not! Anyone got any pointers to a 2x In OR and a 3x In XOR using RTL?

Thanks.

J

 

[barry]

First, I think you need to write out your truth tables, that will help you answer some of your questions.

A 3input NOR is most definitely NOT the same as an XNOR (look at your truth tables!)

Yes, if you invert the output of a NOR you'll have an OR. And vice versa.