Two input TTL NAND gate

188

02:12:48

I was trying to build a 555 timer the other day from discrete components and ran across a transistor that not only had I never seen but also found out that you couldn’t attain.  It’s called a dual emitter transistor and has two emitters.  Searching for an alternative, I ran across this schematic that said it’s nothing more than a nand gate without the amplification.  So here it is.  If I’m wrong on this or you can educate me, please do!

published 5 years ago

PrathikP

5 years ago

Yes, transistors with multiple emitter or multiple collectors are used in ICs. As far as I know, you don't get them seperately. And as for your circuit, it is DTL. DTL stands for Diode-Transistor Logic. TTL, on the other hand, stands for Transistor-Transistor Logic.

Molar

5 years ago

Thanks PrathikP!

fatcat2

5 years ago

With 3 transistors, you could make a more efficient TTL NAND_gate2.

Molar

5 years ago

Fatcat, could u post the circuit?

BillyT

5 years ago

In the early days of transistors, there was a lot of dual emitter transistors, also there were 6 legged packages with 2 matched transistors on the same substrate.

fatcat2

5 years ago

My tab is stupid and dumb. Its just garbage. Its so slow that I can't even post an unlisted circuit. Here is the "discriptive version"__---__----_-__-_::""""""There are 2 two transistors whose bases and collectors are connected together. There is a third transistor which has its collector connected to Vcc via a 22k ohm resistor and its emitter grounded. The grouped collector is connected to the base of this transistor. The grouped bases are connected to Vcc via an another 22k ohm resistor. The left-out emitters are the inputs. Vcc=5V. Hope this helps; sorry for the bad explanation🐱😸

Molar

5 years ago

Fatcat, followed your instructions but got an AND gate with output off of the lone transistor.

fatcat2

5 years ago

http://everycircuit.com/circuit/5313848515756032 Its the cat!🐱🐸😸😂

Molar

5 years ago

Fatcat, dude you ran the inputs through a NAND gate. You cheated.😂

fatcat2

5 years ago

😵!

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