What type of Transistor would work?

I'm making an automated PIR motion-sensor activated-LED system for my room.

The LED is 12V (1.2 Amps per meter x 5 meters) = 6 Amps of current.

Using a transistor (NPN 2N5088 General), I would like for the motion sensor (which outputs 3.3V whenever activated by movement) to activate this 12V LED light line.

I have my ground for the LED connected to the collector and emitter (no issue here).

I'm having issues with activating the Transistor with my PIR Motion Sensor (closing the Collector/Emitter switch) since my motion sensor (hc-sr501) seems to not have enough Voltage or Current for the Base of my transistor.

What type of transistor would support the 12V / 6 Amps line and be sensitive to a 3.3V and small current from my PIR motion sensor or my Arduino?

PLEASE HELP!

A IRLZ44N should be able to pass this current quite easily at 3v Vgs.
.

Hi,

I have my ground for the LED connected to the collector and emitter (no issue here).

Big Issue, you have collector and emitter connected TOGETHER at the gnd??????

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

This is essential if you are to get any useful advice.

Thanks.. Tom.. :slight_smile:

The 2N5088 has Ic of 100mA and the OP is trying to use it to switch a 6 A load.

Wait, How did he calculate the 6 amps ?

The LED is 12V (1.2 Amps per meter x 5 meters) = 6 Amps of current.

Can Someone explain that ?

LarryD:
A IRLZ44N should be able to pass this current quite easily at 3v Vgs.
.

No, its only rated for 4V of gate drive, the plateau voltage is too high to use at 3.3V it
will probably melt.

Normally MOSFETs which run from 3.3V drive are surface mount only. That's life, but usually
you don't drive MOSFETs direct from low voltage logic anyway.

What you should do is use a MOSFET driver chip (these run off your 12V supply), to boost
the 3V3 logic signal to a powerful 12V gate drive - then you can use any non-logic-level
n-channel MOSFET (much more choice), choose one of 10 milliohm or less and it won't
need cooling. You will also be able to use PWM without switching loss issues.

There are 1000's of suitable low-side MOSFET driver chips, I happen to use MIC4422's which
are complete overkill really (are available as DIP package at least).

Here is a (very) rough schematic of my setup:

So there isn't an off-the-shelf transistor that would be fulfill my needs?..

Do you know What a transistor is ?
do you know how to use a PIR sensor?

No, its only rated for 4V of gate drive, the plateau voltage is too high to use at 3.3V it
will probably melt.

I have 4 of these, running at 2.5Vgs, Id = 7.5 amps, but maybe they came from a super good batch.

.

MalharD:
Do you know What a transistor is ?
do you know how to use a PIR sensor?

The PIR motion sensor outputs 3.3V from an output PIN when it detects motion, is powered with 5V - 9V.

Transistor has a base, which closes a switch between a collector and an emitter.

Does something in my schematic lead you to believe that I have a fundamental misunderstanding of either of these components resulting in a faulty circuit?

fnt007:
Transistor has a base, which closes a switch between a collector and an emitter.

No it doesn't. It's a lot more complicated than that. See Transistor - Wikipedia for a start.

Does something in my schematic lead you to believe that I have a fundamental misunderstanding of either of these components resulting in a faulty circuit?

Yes!

Russell.

Does something in my schematic lead you to believe that I have a fundamental misunderstanding of either of these components resulting in a faulty circuit?

Yes,

-Malhar

Your drawing, sadly, is not much of an explanation.

Is there a transistor that will work? Certainly.

Can we tell you which one? Not yet, as it remains unclear what you are doing.

While this drawing was drawn for something entirely different, it does show how to connect one. Bottom pin is Source pin, left side is Gate pin and topside is Drain pin. Where I show 5V separate supply, you could just as easily have 12V separate supply.

The mosfet driver chip is also good advice, since driving mosfets from 3.3V is tricky.

You should use a circuit like the one attached :slight_smile:

Cheers,
Terry

Here is a (very) rough schematic of my setup:

Does something in my schematic lead you to believe that I have a fundamental misunderstanding of either of these components resulting in a faulty circuit?

I have my ground for the LED connected to the collector and emitter (no issue here).

Actually, there is nothing correct about that “schematic”

Spend some time researching “using power transistor to drive 4A load”

In fact, start by learning the basics about transistors, like why you need a base resistor, which you clearly don’t have. You have a 22 k ohm resistor but it is impossible to tell where it is supposed to be connected in your drawing. Look at the two other schematics posted in your thread and then go back and redraw your schematic correctly with a pen on a blank sheet of printer paper like the last poster did and post a photo of it.

fnt007:
So there isn't an off-the-shelf transistor that would be fulfill my needs?..

Well, there are power darlingtons
http://eu.mouser.com/Semiconductors/Discrete-Semiconductors/Transistors/Darlington-Transistors/_/N-ax1sbZscv7Zlls6?P=1z0y4ciZ1z0y4diZ1z0z63x

But like others, I'm not at all sure you know what you are doing. If you compare your post #5 and a real schematic in post 12, why I think that. Perhaps you you should send a good photo of what you have done.

Power mosfets are modern and perhaps even better here.

But like others, I’m not at all sure you know what you are doing. If you compare your post #5 and a real schematic in post 12, why I think that. Perhaps you you should send a good photo of what you have done.

The popularity of led strips and led displays has attracted a lot of non-technical people into dealing with electronics with no experience. In general, the ones who have the least problems are the ones who come right out and disclose their lack of experience with electronics in their first post in no uncertain terms. The ones who have the most problems are the ones who try to pass as electronics experienced but are not by any means. The mess that was posted as a “very rough sketch” and should have been posted as “a desperate attempt to illustrate electronics circuit by someone who knows nothing about them” is a red flag to say the least. Almost all first time posters are electronics newbies so there is nothing new about that. What we are comfortable with is newbies admitting they are newbies and asking where to start. You should start over like the following:

“Hi, I’m a newbie. I don’t have a clue about electronics but need to install a led strip and motion sensor. Can you please talk me through this difficult (for me ) task and tell me where to start ? (FYI, I’ve never drawn a schematic before so I may need some help there. thanks”

Have you read the datasheet for your transistor ?
2N5088

The LED is 12V (1.2 Amps per meter x 5 meters) = 6 Amps of current.

The 2N5088 transistor is rated for 100 mA of continuous current.
Can you now see what are concerns are here ? (What do you suppose happens to a 100mA transistor when subjected to 6000 mA of current ? Do you really want to burn your house down ?)

Cut the BS and come clean. (tell us how much experience with electronics you have before we proceed any further so we know what issues to address in that regard)

LMI:
Well, there are power darlingtons
http://eu.mouser.com/Semiconductors/Discrete-Semiconductors/Transistors/Darlington-Transistors/_/N-ax1sbZscv7Zlls6?P=1z0y4ciZ1z0y4diZ1z0z63x

But like others, I'm not at all sure you know what you are doing. If you compare your post #5 and a real schematic in post 12, why I think that. Perhaps you you should send a good photo of what you have done.

Power mosfets are modern and perhaps even better here.

A darlington transistor is a poor choice for a 12volt LED strip and a 12volt supply.
A darlington could have 1.5volt across when fully 'on'. A bad 'switch'.
Your LED strip could draw 1/4 to 1/3 of the rated current (less bright).
Or, with an RGB strip, have dimmer green and blue light than red light.
You could compensate with a 1.5volt higher supply.
Heat could also be a problem (volt drop x current = watt).
A heatsink is needed if >=1watt.
Logic mosfets are almost ideal switches, and don't have these problems.
Leo..

I think an FQP30N06L on a proper heat sink would work.