Stepping up PWM power

Hey there. Long time no posting.

I want to control RGB LED light strings with my Arduino, of course using PWM. Problem is I don't know how to increase the output power of the Arduino to be able to power multiple runs of RGB LED strips.

These are the cheap LED strips from China that are 5M long. I want to have up to 20 of them.

I know Relays don't work. Can someone point me to what does work? Cheaper the better.

Also, along the same lines, i'd like to eventually run some NEMA 23 stepper motors from an Arduino so if I can use the same "technology" to run those as I can for the light strings, that would be cool.

Thanks.

You can use N channel MOSFET with connection something like this

|500x212 Driving RGB LED strips off an Arduino

That's probably exactly what I need. The picture is a little small to make out what all is going on there.

Thanks

Bad idea to use that Fritzing diagram.

100ohm resistors are (wrongly) drawn from pin to ground. That results in a pin current of almost 50mA. That could damage the pin. Leo..

http://www.gammon.com.au/motors

sterretje: http://www.gammon.com.au/motors

Thanks. I was unsure if this would work with the LED strips. I remember trying something like this two years ago. It was with a different project and it seemed the circuit didn't work unless I added a pulldown resistor and then it seemed to overheat something. Someone, back then, said that the problem might have been that the motor would keep the circuit charged. I was using small LEDs as the test circuit and they wouldn't go off when the arduino went off. I'm sure it was something I did wrong but the result was I burned up an UNO. I thought maybe I had a defective UNO so I hooked up a second one and promptly burned up that one also.

I'm thinking it's time to give it another shot based on the number of hits to Gammon's web page.

Bittsen:
That’s probably exactly what I need. The picture is a little small to make out what all is going on there.

Thanks

If you click the link on Bill’s post, you’ll go to an Instructables project where the circuit is described and shown in greater detail and magnification. Just wire it up.

Bittsen:
Thanks. I was unsure if this would work with the LED strips. I remember trying something like this two years ago. It was with a different project and it seemed the circuit didn’t work unless I added a pulldown resistor and then it seemed to overheat something. Someone, back then, said that the problem might have been that the motor would keep the circuit charged. I was using small LEDs as the test circuit and they wouldn’t go off when the arduino went off.
I’m sure it was something I did wrong but the result was I burned up an UNO. I thought maybe I had a defective UNO so I hooked up a second one and promptly burned up that one also.

I’m thinking it’s time to give it another shot based on the number of hits to Gammon’s web page.

Yeah, read Wawa’s post. Be careful with the current. Look twice at any resistor or wire going to ground. That is why you burned up two Arduinos. (The first one was a learning experience - valuable and worth it. But the second one … tsk.)