Technical, Techniques, Hints, and Tips > Microprocessor control

Home Made PCB Board

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The Old Fart:
if (rcvalue>1500) digital.write(leds,HIGH);
else digital.write(leds,LOW);

somit like that.

The Old Fart:

--- Quote from: Brian60 on February 04, 2018, 05:34:00 pm ---Liking that Tim, take a look at this schematic I'm working on in Fritzing.

 Arduino nano to two shift registers, to rather a lot of mosfets %% All this to control the multitude of led's I have installed, we've discussed this on the arduino forum and I think this is my best way forward. The mosfets are because I have linked leds together and their total current draw is greater than the outputs of any of the arduino boards.

Now all I have to do is finish it off and then turn it into a pcb :}

--- End quote ---

Think you need resistors in each gate leg. just in case mosfet voltage backfeed to control chip.
A resistor is also needed to pull the gate voltage below threshold switch on.
Your switching the positive side on mosfet, so you need a negative voltage to make mosfet conduct.
I have made boards with uln2803a to interface between arduino and mosfet.
the 2803 will take 500ma per leg, 4Amps per chip. use without mosfet to switch negative side.

hope that makes sense, ...

Brian60:
The first part made sense - I have not yet put in the resistors to stop voltage backfeed ( I did say I was still working on it) The circuit is to give me a rough layout and to see what quantity of parts I need.

I didn't understand the part about needing a negative voltage to make the mosfet conduct? So far I have followed online descriptions of similar circuits -  could you explain a little more?

This is the diagram I am working off of, as you see it shows a resistor in the gate line. Are you saying I also need the one shown in the diagram between drain and the VDD, could you explain this part to me if so.

The Old Fart:
that mosfet is switching the negative rail. Your drawing shows switching the positive rail.

timgarrod:
really please,

just had it running for about 30 min. All running leds, smoker (24 inverter ) and fan and all stone cold and no majic black smoke :)

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