Common Positive LED lights

Do you have a link to the LEDs?

Mike.

Couldn't find any specification on that page. Are you able to measure the current draw of each colour.

Mike.

Output/draw
Lumens: Confidential
Draw: Approximately 100mA per color channel @13.5vdc
Max Voltage: 14.5VDC

rrekih said:

I am running common positive led lights RGB. They require the 12VDC to run on the negative (black) wire going to each light.
In turn when I ground out one of the RGB (wire) lights they light up.
I am using a common negative switch for doing so that I have run through relays.

Click to expand...

Something confused there???

The LEDs need negative power switching. The controller is common negative.

That says the controller switches the negative, exactly as the LEDs need?

What exactly is the "controller"? It's shown as six connections, nothing commoned in the sketch?

The controller switch's a relay that gives the led a path to negative.
I put the whole schematic in.

rrekih said:

I am using a common negative switch for doing so

Click to expand...

The relay and LED side is plain.

It's the controller description that does not make sense; "Common negative" implies it switches to ground??

The connections from it are all shown individually, without any common or power/ground info, so it's not clear what it is switching where or how??


Do you mean that is is intended for LEDs that have their common to negative (0V)? In other words, the controller switches the positive side?

If so, you could use appropriately rated transistors or MOSFETS, so they are switched on by the positive signal and pull the LED connection to near 0V.

Example, something like this, using a MOSFET - one of the LED colours being where the lamp is shown:



Rin limits the peak current gate charging current, and if the control voltage is higher than the required or maximum gate voltage, that and Rgs act as a divider to limit the voltage to a safe level.

Rgs ensures the MOSFET is off when there is no input.

For a typical power MOSFET the gate should be at around 10 - 12V for minimum dissipation when "ON".
If the control device produces a 5V signal, then you need "logic level" MOSFETs that can operate with lower gate voltages.

sorry for the late reply, I had a fall yesterday and I am recuperating.

The connections from it are all shown individually, without any common or power/ground info, so it's not clear what it is switching where or how?? The controler has all the negitives common to each other, there is continuity between each negative terminal.


Do you mean that is is intended for LEDs that have their common to negative (0V)? In other words, the controller switches the positive side? Yes the controller switches the positive on and off.

In looking at using a Mosfet it would be taking the place of the relay that I am using now?
I was hoping that there might be a way to cheat the system other than the way I am using.

rrekih said:

Yes the controller switches the positive on and off.

In looking at using a Mosfet it would be taking the place of the relay that I am using now?
I was hoping that there might be a way to cheat the system other than the way I am using.

Click to expand...

The MOSFET circuit I showed would be suitable then; one MOSFET and two resistors for each colour,

What voltages do the controller and LEDs operate on?

there are many solutions for replacing <2A relays

I may suggest FDP55N06 / FDPF55N06 N-Channel UniFETTM MOSFET 60 V, 55 A, 22 mΩ $1.58 v TO220

Automotive 12VDC
I don't think this will work for me though?

rrekih said:

Automotive 12VDC
I don't think this will work for me though?

Click to expand...

That may work; it's pretty much MOSFET circuits something like I posted, plus opto-isolators.

You have not said what voltage the controller and LEDs operate on, yet?

12V DC
Im wondering about the outputs as it seems the board it switching the input voltage.

rjenkinsgb said:

Something confused there???

The LEDs need negative power switching. The controller is common negative.

That says the controller switches the negative, exactly as the LEDs need?

What exactly is the "controller"? It's shown as six connections, nothing commoned in the sketch?

Click to expand...

For simplicity, can't your controller uses a common connections for the relays? That layout is time consuming.

I don't understand your, "common connections"?

rrekih said:

Im wondering about the outputs as it seems the board it switching the input voltage.

Click to expand...

The outputs are switched to 0V as you need for the LEDs; the OUT+ terminals are all connected directly to power +

There are photos from different angles & the board underside in this listing:

You can see all the output side "+" terminals are tracked together.

Out of 40k choices of FETs , I suggest this one for you, $1.50, get a bunch.

rjenkinsgb said:

The outputs are switched to 0V as you need for the LEDs; the OUT+ terminals are all connected directly to power +

There are photos from different angles & the board underside in this listing:

MOS FET 4Channels Pulse Trigger Switch Controller PWM Input Steady for Motor/LED | eBay

The module is based on FET model F5305S. FET module, input and output totally isolated from each other. 1 x Trigger Switch Module. current is 20A. Arduino Module.

www.ebay.co.uk

You can see all the output side "+" terminals are tracked together.

Click to expand...

i see that now, like using common positive as I need and switch the neg.

Tony Stewart said:

Out of 40k choices of FETs , I suggest this one for you, $1.50, get a bunch.

https://www.digikey.ca/en/products/detail/nexperia-usa-inc/PSMN4R3-30PL-127/2122715

Package	Tube
Product Status	Active
FET Type	N-Channel
Technology	MOSFET (Metal Oxide)
Drain to Source Voltage (Vdss)	30 V
Current - Continuous Drain (Id) @ 25°C	100A (Tc)
Drive Voltage (Max Rds On, Min Rds On)	4.5V, 10V
Rds On (Max) @ Id, Vgs	4.3mOhm @ 15A, 10V
Vgs(th) (Max) @ Id	2.15V @ 1mA
Gate Charge (Qg) (Max) @ Vgs	41.5 nC @ 10 V
Vgs (Max)	±20V
Input Capacitance (Ciss) (Max) @ Vds	2400 pF @ 12 V
FET Feature	-
Power Dissipation (Max)	103W (Tc)
Operating Temperature	-55°C ~ 175°C (TJ)
Mounting Type	Through Hole
Supplier Device Package	TO-220AB	$1.5

Click to expand...

I'm sure this would work but I would have to build it.
I'm not setup for building cct. board as such.
The other one is setup already and not expensive.