What kind of transistor is needed and how to include?

There is a piece of programmable RGB ribbon. The management is done with the WS2801 chip. (for a detailed description www.adafruit.com/datasheets/WS2801.pdf ). You want to pull the led, and instead to connect the segment of the tape (with its own power supply).

Picture the desired result is attached. 73f8547de32040d894701a5700bc306a.jpg
The problem is that I don't know what scheme I is more suitable (red or green) and what is the transistor you need ( well, I'm not strong in this, so please help). I only know that the maximum length for the segments that will be inserted after the transistors, is 2 meters.
Tape consumes = 0,06 mA (each led) x 64 (number of LEDs on 2 metres of segment) = 3,84 A.
So the transistor must be able to withstand 4A. Power on the tape either 5 or 12 volts.
Yet as far as I remember, they need a resistor, but I could be wrong.

If I do something wrong or made a mistake do not judge strictly. Please help this is not difficult. Thank you.
September 26th 19 at 06:47
1 answer
September 26th 19 at 06:49
Will fit almost any NPN transistor.
But the current need to count, because it all depends on the supply voltage, how many are connected in parallel.

If the power strips 12volt (each led roughly 3 volts), we get successively connected should be 4 LEDs(the current consumption is still 0.06), but again it is necessary to power the LEDs 64, 64/4 = 16(so must be connected in parallel), and the current consumption is already becoming a 0.06*16 = 0.96 amps. Ie the transistor need to take on more 12volt voltage and current of over one ampere.

I personally have never worked with led strips, so I don't know how my version is acceptable, but in terms of power consumption and heat dissipation on the transistor - it is clearly good.
Thank you and the answer. Please tell me the markings for the transistor which you can buy. And how about the resistor, is it needed? If so what. - Gust.Marquardt commented on September 26th 19 at 06:52
Of our can take кт815,кт817,кт819, they are arranged in order of increasing power.
On account of the resistor are not sure if correctly understood the formula, you need a resistor on the 10-13th and power resistor select 2-3ватта to reserve it. - Sheila.Christiansen62 commented on September 26th 19 at 06:55

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