Complete newbie needs help w/ MOSFET design.

Thread Starter

jeffkrol

Joined Dec 8, 2015
14
I have this constant voltage aquarium light that I found can be divided into 3 channels relatively easy.
Also know that the TC-420 controller will PWM dim LED strip lights. I'm trying to bring the 2 together.
Problem is the MOSFET output of the TC-420 is on the neg side. The light has a negative bus and each channel is on the pos. side..
So I thought the below could basically reverse this condition using a p channel MOSFET as a second pulse width switch.
Important parameters:
15V constant voltage power supply
TC-420 is said to work between 12-24V but I believe some have run it w/ lower input voltage.
TC-430 will not have a "load" to control really..It will just be a PWM output generator..
Current will be in the new MOSFETS.
Anyways the point is to change the neg pulses to positive pulses
Now this may be COMPLETELY wrong but I'd appreciate any feedback on this, EVEN if to say I'm an idiot.. ;)
Anyways a diagram:

 

Bordodynov

Joined May 20, 2015
2,642
I believe that you will not come out. If you persist, you will destroy the LEDs. The device is self-sufficient and is not intended to control the transistors. This device utilizes PWM to control the internal transistors. Dimming is an added bonus comes at a lower frequency.
 

Thread Starter

jeffkrol

Joined Dec 8, 2015
14
Hmmm thanks for the response.. but the tc-420 can control 4A 15V of LED's at it output.. Controlling the gate of a MOSFET should be no problem.. In a sense all I am doing is putting a high speed switch onto another high speed switch..
I have more worries about destroying the added MOSFET's and/or the TC-420 more than the LED's.
Parts are in only a few details need to be worked out..
 

Bordodynov

Joined May 20, 2015
2,642
The LEDs are powered current, rather than voltage. tc-420 is a current source. Without load tc-420 will provide 15 volts. If you Including series with the P-channel transistor LEDs without current limiting device that will destroy them.
Explain to me the following question. When you write "LED" you mean only LED without driver?
 
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