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Topic: Which transistors should i use? (Read 3130 times) previous topic - next topic

BabyGeezer

It looks like a Link embedded in a Link
or, to be precise, a URL link (to the image) that will be activated when user clicks the image in the [ img ] tags.
Attach your images to be viewed directly - THIS WAY;
https://forum.arduino.cc/index.php?topic=519037.0

MarkT

MOSFET works similar to NPN (2N2222).
Arduino drives a voltage into the Gate thru 150 ohm resistor, (like R1),
Source connects to Gnd,
Drain connects to the 'bottom' of the motor.

Rds of the MOSFET is very low, so the motor will see almost all of the battery voltage, vs the NPN wasting 0.7V across the Collector-emitter.

The NPN won't waste 0.7V in saturation, 0.1V more likely.  0.7V is the base-emitter voltage.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

raschemmel

It looks like 0.3V for 50ma  and 1.0 for 500 mA
2n2222
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

puelon

MOSFET works similar to NPN (2N2222).
Arduino drives a voltage into the Gate thru 150 ohm resistor, (like R1),
Source connects to Gnd,
Drain connects to the 'bottom' of the motor.

Rds of the MOSFET is very low, so the motor will see almost all of the battery voltage, vs the NPN wasting 0.7V across the Collector-emitter.

is there any alternative MOSFET to IRL? i would have to import it, and takes to long lol

ted

Check the MOSFET which you already have, you need a switching mosfet, in data sheet look for threshold voltage less than 5V.
example - IRF540
Gate-Source Threshold Voltage VGS(th) VDS = VGS, ID = 250 μA 2.0 - 4.0 V

https://www.vishay.com/docs/91021/91021.pdf

puelon

is there any alternative MOSFET to IRL? i would have to import it, and takes to long lol
Check the MOSFET which you already have, you need a switching mosfet, in data sheet look for threshold voltage less than 5V.
example - IRF540
Gate-Source Threshold Voltage VGS(th) VDS = VGS, ID = 250 μA 2.0 - 4.0 V

https://www.vishay.com/docs/91021/91021.pdf

Yeah i see it: Min 2.0 max 4.0. But i still don't follow, i was told this isnt a logic level MOSFET, therefore i couldnt switch it to what i wanted, and i was looking all around me and far for it and nothing. So, you're saying i could do it with a IRF? im confused

ted

which transistor you are testing ?

puelon

which transistor you are testing ?
IRF540, but i cant get it to work

ted


puelon

Start with this

Yeah, but my question remains will a IRF540 suffice?

ted

Make this work then go to next step

puelon

Make this work then go to next step
this circuit is using a transistor and theres absolutely no specification whatsoever, and lacks plenty of information

ted

Just test it and tell me the results.

Wawa

#28
May 20, 2018, 02:02 am Last Edit: May 20, 2018, 02:09 am by Wawa
You were adviced to use a normal bjt transistor with 220ohm base resistor (post#3).
Perfectly ok for a small ~140mA load.
Almost any small/medium transistor can be used for a load like that.
Why are you still trying to use a non-logic IRF540 mosfet.
You like gambling?

...in data sheet look for threshold voltage less than 5V.
Silly advice. A logic level mosfet must have a threshold voltage <2volt.
A Vgt of 2-4volt is a non-logic level type.
Leo..

outsider

#29
May 20, 2018, 02:16 am Last Edit: May 20, 2018, 02:23 am by outsider
I think @ted meant IRL540.
https://www.vishay.com/docs/91300/91300.pdf
A 5-for-a-dollar 2N2222 would work fine.

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