Total Noob here. I have a Project using a Lot of LED’s I am needing to use Mosfets for the high power of up to 50+ LEDs per circuit.
What I want to do is Use the Body of a 3 foot long Copper wire Dragon I made as a common ground for the lights, like a cars body and control the lights on the V+… The N Channel uses the V- side of the load for controlling on/off and fading, P Channel the V+ . Problem is The P works the opposite. I’d need a high signal from the Arduino for off. lots of battery usage at Idle?
Is there a way to use 2 P-Channels??
Arduino Feeding no signal to 1st P,( fed by a low power 5V) sends high signal (but a very low power) to 2nd P, who sends No power to the LEDs. In turn, High signal from Arduino to 1st P. who sends low signal to 2nd P. who send high power to LED’s Then I can use the Dragons body as a common ground?? And How do I wire this set up??
~This also makes the programing of a very complicated sequence, of many circuits, less complicated for these circuits. That is going to a whole other project once I get the hardware made. I do have the help of a Pro code writer though~
BUT… This uses the V- for controlling. Making it impossible to use the Dragons Body as a common Ground.
P.s The plan
(when on Battery) is to use a 12v to 5V step down. Powering the Arduino directly from 12V battery with a fuse and circuit protection.
(When on 120AC) using a Computer Power units 12v for the Arduino, and the 5V out for the system of lights. Each LED will have its own Resistor from 5V to it’s respective Voltage.
Agree with Joe - MOSEFTs don’t use power when they are switched off. As you say, if you use the P-channel devices, you switch them off with a high voltage.
You could instead have the 5V rail as the “common”, and use N-channel MOSEFTs switching the “low side” of the LEDs. Generally N-channel types are cheaper and have a lower “on” resistance than P-channel types, but this is only important for really high currents.
MichaeIN ~You could instead have the 5V rail as the “common”, and use N-channel MOSEFTs switching the “low side” of the LEDs. Generally N-channel types are cheaper and have a lower “on” resistance than P-channel types, but this is only important for really high currents.~ But I’ll ponder it for a while.
As I Said Total noob. Not sure what you mean by this.The N Channel does use the V+ as common controlling current from the V- side. This is the Problem I have. I want to reduce the mass amount of wires needed for this project by using my uninsulated COPPER WIRE Dragon as my common ground. Each LED neg lean connected directly to the Dragon. As for lights that just flash on/off I plan on using relays, or pre-made chasing units w/ add ons for higher power usage. Then I only use 1 Pin on the Arduino to turn that circuit on and off at the right times.
Joeisi- Thanx for the link. But I may just use single pins from Controller to run all kinds of different LED kits I am finding. The project will get more expensive But I will only need the “UNO” and a few voltage converters, and bunch of relays. I’m finding a lot of units that run on 9v. I am finding some really cool looking units.
I believe what MichaelN was trying to point out was that you can use the more common N channel FETs, it’s just that the FET source(s) would be tied to your common copper Dragon ground, not the LED cathodes. The LED(s) would then be tied to the FET(s) drain(s), as the motor was in your link above. The wires to/from the Arduino would be the same in either case.
But I think you have a larger concern than how to wire up a FET and LED. When you say 50+ LEDs and “high power”, this makes me wonder how you’re planning to control all these LEDs. Are you going to have banks that come on all together ? Are they to be just on/off or are they going to be on/dimmed/off ? High power LEDs usually use a special current controller and not a FET+resistor to control their current. What’s your plan for these (if they exist) ? Switching a bank of lesser power LEDs would have the same issue.
I’m going to need to do some experimenting. Actually My plan is for up to 25 LED’s per circuit. Most are @ 2V 20ma. Using high amp relays to power the on/off ones. and Mosfets for the fading ones. Though I am finding units that do all kinds of things pre-programmed. Now to see if I can amplify, and isolate power from these units, so instead of controlling 1 led each, connection powers like 10-25. I have found some units that will work for 8 channels and up to 2amp per channel. @20ma that’s (100x20ma) so operating 25 would only be .5amps. I also found kit’s that will chase up to 10 LED’s. bridging all the board connections w/ wires is were I’ll have to experiment.
At half an amp I would suggest building a LED driver. There are lots available on Digikey. You will waste more power through the resistor(s) than through the LED itself. Its just not efficient.
I was wrong about 2amps it’s .5 per channel. to power 25- 2V 20ma 1.8 mm LED’s My hope is that I can 2 of the FK090 to run 5 circuits of 50 lights. total of 250. this is The Dragons Fire on 10 strings. a 5 circuit chasing so I stagger the bulbs. Parallel, 1-5 each string. if this works out. There is another kit that does 10 LED’s that does all kinds of patterns. I’ll have spare circuits on the FK090 and a 3rd one, to power the last 2 LED’s per string That twinkle randomly. So that unit needs to run only 2 bulbs per circuit. I get the power loss from resistors. If I power the FK090’s from a 5V or even 3.3V Power rails off a computer power unit. Mine is rated for 20amps. Or converters you can get for now a lot of $. example(12V to 3.3V, Step-down, 3A, 10W` $9 +shipping) Then the resistors aren’t dropping a lot. At least this is my theory so far. I may not be getting into the Mosfet’s at all. tell later were I need fading. Though I may find pre-made kits for that too.