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What Do These Mean? Answered

I'm trying to construct an entry for the Wicked Lasers contest, however I keep on finding the same letters on several diagrams... 

Can anyone tell me what the G, S and D stand for?

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steveastrouk

Best Answer 7 years ago

GATE
SOURCE
DRAIN

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thomas9666steveastrouk

Answer 7 years ago

Thanks.... But what do these mean?


Sorry for being stupid, electronics isn't taught for another 2 years at my school.

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steveastroukthomas9666

Answer 7 years ago

If you're building from an existing diagram, just follow it. Like Sean says, its a MOSFET, a field effect transistor, how it works is tricky to understand.

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seandoguethomas9666

Answer 7 years ago

The device is a Field Effect Transistor, a type of transistor that uses an electric field to change the impedance from drain to source from near-infinite to near zero. They can be used as switches and amplifiers, amongst other uses.

A voltage is applied to the Gate terminal to determine the state of the drain/source impedance.

IMO, you should google it or go to wikipedia for a lengthy answer.

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7654321

7 years ago

A current at the gate makes current flow from the drain to the source (yes the names sound backwards)

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steveastrouk7654321

Answer 7 years ago

NO There is no steady gate "current" MosFETs are voltage driven at the control, unlike BJTs.

Steve

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seandoguesteveastrouk

Answer 7 years ago

right.

In fact, for all intents and purposes, (and aside from hair-splitting) there isn't any current at the gate, steady or otherwise.

FETs are voltage controlled devices.

A BJT however, can be (in some ways) modeled after a venturi. Flow (literal) from the Base to emitter is necessary to switch the collector/emitter flow. And in fact it is directly proportional to that flow by the Hfe

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steveastroukseandogue

Answer 7 years ago

Me ? Split hairs ?
I WAS thinking of gate capacitance charging.

Steve

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seandoguesteveastrouk

Answer 7 years ago

oops. NO I didn't mean you were splitting hairs. was just trying to imply that yeah...there may be current, but it's tiny and simply a parasitic rather than a causal like in a BJT.

Just trying to keep my comment in the thread rather than making it possibly non-sequitur by posting separately...

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steveastroukseandogue

Answer 7 years ago

Hehe
Its alright, I am a champion hair-splitter ;-)

Steve

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seandoguesteveastrouk

Answer 7 years ago

HA! I was right then. you woulda caught me on it if I hadn't added that qualification. NYAH! ;-)

(as if I'm anyone to talk)

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seandogue7654321

Answer 7 years ago

The gate voltage (not current) does not make anything happen other than to reduce the impedance of the semiconductor junction.

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76543217654321

Answer 7 years ago

Actually I think it can go both ways, nevermind