# Digital electronics

Discussion in 'Electronics Homework Help' started by Praveshchauhan95, Mar 2, 2013.

1. ### Praveshchauhan95

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Mar 2, 2013
Why OR,NOT,AND gate r design by universal gate (NAND,NOR) is any advantage to do this..?

2. ### BobK

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Jan 5, 2010
Transistor logic is always going to have an inverter. You would need to add an extra inverter to get an AND or OR gate, so you might as well make the NAND and NOR the primary gates and derive the AND and OR from them + an inverter.

Bob

3. ### ElectronicsPani

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Mar 3, 2013
You can build a NAND gate and NOR gate using minimal amount of transistors. And you can make other gates using minimal ammount of universal gates.
So in most cases Digital Gates are made by combining NAND and NOR gate.

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
And a single input NAND gate looks like? (compare with a single input NOR gate, and also an inverter)

5. ### Praveshchauhan95

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Mar 2, 2013
i m very confuse about what is the different btw ttl and cmos technology how the r differ in there fabrication plz describe me in deep or give any link that give complete knowledge ..........................thnx!!!!!!!

6. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
One used bipolar transistors, the other used mosfets. That's the basic difference.

Apart from that, the functions are the same, but voltage levels and speeds can vary.

wikipedia can explain more.

7. ### Praveshchauhan95

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Mar 2, 2013
How SD memory card work .....?
Why it's memory is not volatile...

8. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Perhaps you should do your own homework?