Usb trigger for 12v TV backlight

[carpenter940]

I have a strip of 12 volt LED lights that I'd like to use for a TV backlight. I'd like the LEDs to come on/off when the TV is powered on/off. I'm using the USB on my TV as my trigger.
Will someone take a look at it to see if it's OK to use on TV w/o destroying TV?

The parts I will use are:
USB cable connected to 5v USB out on TV
R153S Diode (the R153S was the only indicator of it's value)
1/4W 0.25W 5% 220 R OHM Carbon Film Resistor
IRF520 Power MOSFET N-Channel TO-220 GM
Led Strip 3528 SMD White lamp DC 12V
12v source for LEDs

Below you will find a link to the schematic.
http://tinyurl.com/y84rxw35

Thanks for any help.
NOTE: I'm not very good at electrical circuits.

 

[Externet]

I do not see anything wrong with it.
You could choose a relay if makes you sleep better.

 

[BobK]

IRF520 requires 10V to turn on fully. It might work at 5V, but typically cannot pass more than 2A at that gate voltage, and will be dropping between 1 and 2V at that current. You need a logic level MOSFET like the IRLZ44.

Bob

 

[carpenter940]

Thank for the replies. Now that I went back and looked at the data sheet for the IRF520 I see it DOES require 10V, but you wrote it may work at 5v too. I decided to take a chance since I already had a IRF520 and constructed the project and it seems to be working fine plugged into a 5v phone charger. I'll leave it plugged in for awhile to make sure it doesn't melt before plugging it into my TV.

 

[Harald Kapp]

but you wrote it may work at 5v too. I decided to take a chance

If it works, it may not be reliable. It may be seemingly on, but have a comparatively high drain-source resistance which will heat it up, shortening its lifetime considerably. I really recommend you follow Bob's advice.

 

[carpenter940]

Not a bad idea. I'll go get a IRLZ44. Thanks

 

[BobK]

I would expect the MOSFET to get quite warm if not hot with 5V on the gate. How much current is the strip using?

Bob

 

[carpenter940]

The strip had 75 LEDs on it so about 1.5 amps. Actually I plugged it into a phone charger as a test for over 2 hours and the MOSFET was still room temperature, didn't feel warm at all, kind of a surprise.