noob: +12 transistor needed, HOW to and which one?

so basicly, what i have is an led strobe kit. i have oodles of led's on it, it has 2 outputs rated at 3A per output. im drawing 1.24A per side so im not even half way to its peak. however, its not putting out +12 on the strobe outputs.
BTW, its a sho-me 11.1005 LED Flasher - Standard from here: https://www.electro-tech-online.com/custompdfs/2007/05/11_1005_1005SF_instructions.pdf

so, basicly, i need a transistor i believe as they are current switchers and are very very fast. i could be done already w/ relays, but the click click would get annoying and i dont think theyd last one show.. LOL.. so basicly, i want to put in some transistors but cant figure out which one i need. as i need one that triggers from like 3V-15V and will output exaclty what is fed at the collector, so in this case, would be 13.4V (my cars V at idle)

things i've tried already to head off questions... took some jumpers and added to the ground of the "kit" to test if it had sufficent ground, all good. added a 16ga jumper to the power wire to make sure it was getting enough +12V, all good. measured my current draw of the led's per side to see if i had a short, all good, both sides 1.24A (tested not strobeing, lit up the led's via the DVM on I to constant 12V). put DVM on strobe outputs and it tested like 6V at the highest as my fluke cant read it till it slows down but 6V is the only number i can read on my meter as the strobe flash goes down.

thanks in advance, hope i made sense as im kinda a noob...

Your multimeter can measure DC and measure continuous AC, but not pulses. So maybe the strobe circuit puts out 1.24A and if you add a power Mosfet to boost the current then the LEDs might burn out.

How do you have the LEDs hooked to it? The current draw is dependent on the load, so maybe you could just add some more LEDs to each side?

well, everything is made to run at 13.7V as thats my cars running voltage. so, what im flashign is my led fog lights that i built, my custom led tails and what not.. so everythign has current limiting resistors so its all good. it says it can handle 3A, but im only drawing half that.. i need a boost, and just need it to output more voltage.. dont care if it will burn them out, as i know it wont. and its an led flasher, so it dosent require a load. it would flash one 20ma 3mm led per output if thats what i had hooked up to it..

basicly, just need to know how to wire a transistor to up the voltage from a fast switching +12V source..so basicly a relay and the exact same principal of a relay just using a transistor as it is dosent make any noise and has is built for fast switching sources...

the current output is dependent on the load you put on it! So why not just cut your current limiting resistors in half to double the load?? You'll probably burn out the LEDs though.

If you start to get above 3A, then I would worry about using a transistor.

i think your missing what i am doing. the fogs, tails, blinkers are all custom led mods that i've done. w/ engine running, each led is at its rated V and I and are bright as i designed the circuit to be. that is fine, so my brake lights are bright, my led fogs are bright, its just when i put them on the led flasher "strobe" kit, they arent bright. all added up, measured w/ my DVM, they only draw 1.24A. that is measured at the +12 supply to ALL the led's (measured w/ a direct feed from the battery, not the current draw from them while they are on the flasher, that amperage is at the led's full brightness. so it wont ever go above 1.24A. thats all the leds' draw all together per side. so it will never get to 3A, only less than half when all led's are at full brightness.. so, basicly, its the led flasher thats not kicking out my current, thats what i need the transistor for.. max for that trany to draw is gonna be 1.24A no matter what.. the led's dont draw any more than that and never will...

i just need a trany that will take the low voltage the led flasher is kicking out, and switch it via a transistor that is getting fed 13.7 from the alternator, and have that go out the output to power the led's... for full brightness..

get what im saying? i just need to know how to do it, current draw is fine, cant possible blow the led's.. if i change the resistor for the led flasher, when i use the led's as fogs, they will burn out.. the are wired now for 13.7V, its the lack of V the flasher kicks out that i need to boost!

A TIP31 transistor has a max pulse current rating of 5A. It has a typical saturation voltage of 0.2V at a load current of 1.24A when its base current is 124mA. Its max saturation voltage at those currents is about 0.8V.

The base of the transistor needs to have a pull-down resistor of about 2.2k to turn it off and a series current limiting resistor of about 56 ohms if the flasher can put out 8V.

now were getting somewhere! thats what i needed!

so, to get this straight to me, at a draw of 1.24A, im gonna lose, .8V from the source, so if i have an alternator V of 13.7, im looking at about 12V to the led's? am i grabbin that right?

the location of the resistors is beyond my knowledge. can you draw a quick sketch purty purty please?

thanks man!

The transistor will have a 0.2V drop or up to a 0.8V drop (each transistor is a little different). So the LEDs will get 13.5V or from 12.9V and up.

The transistor will become warm but won't need a heatsink.
Wire it like this:

audioguru said:

The transistor will have a 0.2V drop or up to a 0.8V drop (each transistor is a little different). So the LEDs will get 13.5V or from 12.9V and up.

The transistor will become warm but won't need a heatsink.
Wire it like this:

Click to expand...

cant. the led's are hard wired. i cant seperate the grounds as they are shared and are grounded right to the chassis.. is there a way i can just get a +13V switched output from a simular circuit?

This circuit will turn on your grounded LEDs when the flasher voltage goes high:

What's wrong with power MOSFETs?

Hero999 said:

What's wrong with power MOSFETs?

Click to expand...

A P-channel power Mosfet is much more expensive than a TIP32 PNP transistor. It would also need another transistor as an inverter.