Arduino Forum

Using Arduino => General Electronics => Topic started by: puelon on Mar 17, 2018, 03:48 am

Title: Which transistors should i use?
Post by: puelon on Mar 17, 2018, 03:48 am
Hey guys, Im doing a project that i need to turn on a mini fan that has 5v and the IC is 0,140A, i need a transistor is able to my arduino port from 20ma to 140ma, but i dont which one i should be looking for.
Title: Re: Which transistors should i use?
Post by: ted on Mar 17, 2018, 04:00 am
Hey guys, Im doing a project that i need to turn on a mini fan that has 5
5 of ?
Title: Re: Which transistors should i use?
Post by: CrossRoads on Mar 17, 2018, 04:03 am
You're looking to sink 140mA?
IRL540 is good, 0.063 ohm on resistance at Vgs = 4V.
https://www.digikey.com/product-detail/en/infineon-technologies/IRL540NPBF/IRL540NPBF-ND/812000 (https://www.digikey.com/product-detail/en/infineon-technologies/IRL540NPBF/IRL540NPBF-ND/812000)
TO220 package, easy to work with.
Title: Re: Which transistors should i use?
Post by: outsider on Mar 17, 2018, 04:04 am
Like this?
(http://forum.arduino.cc/index.php?action=dlattach;topic=535703.0;attach=249784)
Title: Re: Which transistors should i use?
Post by: puelon on Mar 17, 2018, 04:26 am
You're looking to sink 140mA?
IRL540 is good, 0.063 ohm on resistance at Vgs = 4V.
https://www.digikey.com/product-detail/en/infineon-technologies/IRL540NPBF/IRL540NPBF-ND/812000 (https://www.digikey.com/product-detail/en/infineon-technologies/IRL540NPBF/IRL540NPBF-ND/812000)
TO220 package, easy to work with.
Thank you for your time to read and help me, im looking to increment the output from the arduino pin that is by default 20ma, to 140ma. I was reading the datasheet it doesnt specify the collector, base and emitter currents. I am very sorry if i understood something wrong. Basically i am trying to do is make a 5v mini-fan work

@outsider i was thinking the same thing, to use a resistor and a NPN 2N2222 like in your schematics, but what would be output current and voltage in your schematics?
Title: Re: Which transistors should i use?
Post by: CrossRoads on Mar 17, 2018, 04:38 am
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.
Title: Re: Which transistors should i use?
Post by: larryd on Mar 17, 2018, 04:45 am
FYI
See Q3 circuit.
You replace the relay with your fan.
The 12v would be changed to 5v to match the fan voltage.

(http://forum.arduino.cc/index.php?action=dlattach;topic=477829.0;attach=212182)  (http://forum.arduino.cc/index.php?action=dlattach;topic=477829.0;attach=212182)


Click on the image for full resolution.
Title: Re: Which transistors should i use?
Post by: raschemmel on Mar 17, 2018, 07:17 am
Larry,
How did you do that ?
("click on image for full resolution")
Is that a new forum toolbutton ?
Title: Re: Which transistors should i use?
Post by: puelon on Mar 17, 2018, 07:31 am
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.

Very interesting, i will try it, and will update the topic with the results, thanks for the help once again :)
Title: Re: Which transistors should i use?
Post by: ted on Mar 17, 2018, 08:18 am
Larry,
How did you do that ?
("click on image for full resolution")
Is that a new forum toolbutton ?

When I click the resolutions is worse,very good function concept.
Title: Re: Which transistors should i use?
Post by: raschemmel on Mar 17, 2018, 08:27 am
I didn't know there was a "Resolutions" toolbutton.
That's a new one in me, but then I'm so old, everything is new to me. I went out to my car this morning and it looked new to me. All I did was wash it last week and it still looks new. Must be the rain here in California doing that. Beats ice and snow...
Title: Re: Which transistors should i use?
Post by: ted on Mar 17, 2018, 08:42 am
Ice in California ???
I am north of that 2000 km, almost spring.
Title: Re: Which transistors should i use?
Post by: raschemmel on Mar 17, 2018, 08:53 am
High altitude gives me headaches.
Title: Re: Which transistors should i use?
Post by: larryd on Mar 17, 2018, 04:11 pm
Larry,
How did you do that ?
("click on image for full resolution")
Is that a new forum toolbutton ?
Paul__B make a Macro that you can copy and paste, your URL entered as shown.
Code: [Select]
[center] [url= Your_URL ][img width=500] Your_URL [/img] [/url][/center] [center]
Click on the image for full resolution.[/center]




Title: Re: Which transistors should i use?
Post by: raschemmel on Mar 26, 2018, 03:54 pm
It looks like a Link embedded in a Link
Title: Re: Which transistors should i use?
Post by: BabyGeezer on Mar 26, 2018, 04:55 pm
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.
Title: Re: Which transistors should i use?
Post by: MarkT on Mar 26, 2018, 09:00 pm
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.
Title: Re: Which transistors should i use?
Post by: raschemmel on Mar 26, 2018, 10:27 pm
It looks like 0.3V for 50ma  and 1.0 for 500 mA
2n2222 (https://www.onsemi.com/pub/Collateral/P2N2222A-D.PDF)
Title: Re: Which transistors should i use?
Post by: puelon on May 19, 2018, 07:33 pm
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
Title: Re: Which transistors should i use?
Post by: ted on May 19, 2018, 07:55 pm
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 (https://www.vishay.com/docs/91021/91021.pdf)
Title: Re: Which transistors should i use?
Post by: puelon on May 19, 2018, 08:13 pm
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 (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
Title: Re: Which transistors should i use?
Post by: ted on May 19, 2018, 08:32 pm
which transistor you are testing ?
Title: Re: Which transistors should i use?
Post by: puelon on May 19, 2018, 08:39 pm
which transistor you are testing ?
IRF540, but i cant get it to work
Title: Re: Which transistors should i use?
Post by: ted on May 19, 2018, 08:56 pm
Start with this
(https://www.electronicshub.org/wp-content/uploads/2015/02/MOSFET-to-Switch-LED.jpg)
Title: Re: Which transistors should i use?
Post by: puelon on May 19, 2018, 09:19 pm
Start with this
(https://www.electronicshub.org/wp-content/uploads/2015/02/MOSFET-to-Switch-LED.jpg)
Yeah, but my question remains will a IRF540 suffice?
Title: Re: Which transistors should i use?
Post by: ted on May 19, 2018, 09:27 pm
Make this work then go to next step
Title: Re: Which transistors should i use?
Post by: puelon on May 19, 2018, 09:34 pm
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
Title: Re: Which transistors should i use?
Post by: ted on May 19, 2018, 10:22 pm
Just test it and tell me the results.
Title: Re: Which transistors should i use?
Post by: Wawa on May 20, 2018, 02:02 am
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..
Title: Re: Which transistors should i use?
Post by: outsider on May 20, 2018, 02:16 am
I think @ted meant IRL540.
https://www.vishay.com/docs/91300/91300.pdf (https://www.vishay.com/docs/91300/91300.pdf)
A 5-for-a-dollar 2N2222 would work fine.
Title: Re: Which transistors should i use?
Post by: ted on May 20, 2018, 02:26 am
IRF540
Gate-Source Threshold Voltage VGS(th) VDS = VGS, ID = 250 μA 2.0 - 4.0 V

below 2V transistor will not will turn on
Above 4V must turn on
between - it depends on the mood of the transistor.
Logic level or not, 5V is more than 4V
Title: Re: Which transistors should i use?
Post by: ted on May 20, 2018, 02:33 am
A logic level mosfet must have a threshold voltage <2volt.

Silly advice.
Leo..

I don't care about your opinion,
First learn how to be a polite ........
Title: Re: Which transistors should i use?
Post by: outsider on May 20, 2018, 02:51 am
@ted:
 VGS(th) is the gate voltage that barely starts conduction (threshold), if it's 4V then at 5V it would conduct but RDS(on) would be pretty high, the IRL's VGS(th) is 1 to 2V so at 4V it would be at full conduction.
Title: Re: Which transistors should i use?
Post by: ted on May 20, 2018, 03:07 am
Being above the maximum (5V), you can be sure that this way, the MOSFET will be turning fully on and off each time it is switched.
@ted:
  it would conduct but RDS(on) would be pretty high,
not sure about that.


Being above the maximum (4V), you can be sure that this way, the MOSFET will be turning fully on and off each time it is switched.



google - Vgs(th) min/max .
Title: Re: Which transistors should i use?
Post by: Wawa on May 20, 2018, 03:57 am
I don't care about your opinion,
First learn how to be a polite ........
I think Vgt has already been explained to you in previous threads.
It seems you still don't fully understand the concept.
Not a problem, but until you do it's wise to keep advice to yourself.
Leo..
Title: Re: Which transistors should i use?
Post by: ted on May 20, 2018, 04:30 am
to you in previous threads.
I know what is that and don't need any explanation,
on previous thread you have discussed this for a long  time digging in wrong place, where solution was pointed by me, and magik, all 4 MOSFETS start to work regardless of voltage threshold.


Title: Re: Which transistors should i use?
Post by: puelon on May 30, 2018, 01:36 am
Alright so specifying my problem here, around my area theres no IRL at all, i have a few IRF, but from the conversation, i should use a 2N2222?
Title: Re: Which transistors should i use?
Post by: Wawa on May 30, 2018, 01:53 am
I think you were already told in post#3 that a 2N2222 with 220ohm base resistor is ok for a 140mA load.
Leo..
Title: Re: Which transistors should i use?
Post by: MarkT on May 30, 2018, 12:37 pm
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.

A saturated 2N2222 wastes about 0.4V, not 0.7V, that's the Vbe you're thinking of.  Some good modern switching BJTs would have 0.05V saturation voltage for this load in fact.

Note that if using a MOSFET it needs to be a logic level MOSFET, the others need 10V to operate.