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Topic: Correct symbols (Read 634 times) previous topic - next topic

SouthernAtHeart

http://en.wikipedia.org/wiki/Mosfet
Are the N & P channel Mosfet symbols correct in the 4th column of the table at this wiki site?

CrossRoads

Could be - little hard to find a datasheet for a part like that.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

oric_dan

#2
Jan 16, 2013, 11:16 pm Last Edit: Jan 16, 2013, 11:18 pm by oric_dan(333) Reason: 1
Yes, I remember those from a while back. In those the arrows are showing the direction of
current-flow. You'll notice the similarity to the JFETs. Also, similar to NPN/PNP bipolar symbols.

Nowadays, the arrows are used to illustrate the type of substrate, eg, arrow points inward
[ala "cathode"] to indicate n-channel type.

majenko

#3
Jan 17, 2013, 02:41 am Last Edit: Jan 17, 2013, 02:43 am by majenko Reason: 1

Yes, I remember those from a while back. In those the arrows are showing the direction of
current-flow. You'll notice the similarity to the JFETs. Also, similar to NPN/PNP bipolar symbols.

Nowadays, the arrows are used to illustrate the type of substrate, eg, arrow points inward
[ala "cathode"] to indicate n-channel type.


Tip for remembering it:  N stands for Near.

NPN transistor, the arrow Not Point Near.

PNP transistor?  Point Near, Please!

oric_dan

#4
Jan 17, 2013, 02:53 am Last Edit: Jan 17, 2013, 02:59 am by oric_dan(333) Reason: 1
Quote
Tip for remembering it:  N stands for Near.

NPN transistor, the arrow Not Point Near.

PNP transistor?  Point Near, Please!

Ok, here's your challenge. Invent something like this for MOSFETs, based upon the direction
of the diode in the middle of the symbol, :-).

I also seem to recall they used to originally show NPN transistors as analogous to 2
anode-to-anode diodes [opposite for PNP], with the base lead coming out the middle,
although that hardly explains how they amplify. It does however explain why you can
take an ohm-meter and determine the type of transistor you have without knowing its
part number.

SouthernAtHeart

Hmmmmm.....  Seems quite strange that in these two punctures, one is a P channel and one is an N channel.  I'll always have to reference a chart to figure them out! The arrows both point in, they both point from the S

SirNickity

Yeah, that one's a pet peeve of mine.  Pick one and let the other die gracefully.  I don't even care which!  :-)  My schematics software uses one, and sim software the other.  I always have to hover over it for the labels to make sure I'm not getting them mixed up.

SouthernAtHeart

That's kinda it for me too. This new software uses n the old one that's backwards...

oric_dan

#8
Jan 17, 2013, 07:09 am Last Edit: Jan 17, 2013, 07:12 am by oric_dan(333) Reason: 1
Quote
Hmmmmm.....  Seems quite strange that in these two punctures, one is a P channel and one is an N channel.  I'll always have to reference a chart to figure them out! The arrows both point in, they both point from the S


I already explained this in post #2. Originally, all 3 transistor types, jfet, bipolar, and mosfet used similar
[read: consistent] direction-of-arrow diagrams. Now the MOSFETs have a new standard.


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