Did I misunderstand?

Working on a project that uses the output from the microcontroller, thru a 100 ohm resistor to signal a transistor to act like a switch and allow a high voltage (5v) and amperage(1 amp) to pass thru the transistor to power an LED.

So signal from the microcontroller after passing through the resistor goes to the 'base' leg on the transistor. This is 3.3v. The collector of the transistor has 5v to it, and surprisingly when the base activates the switch, I get only 2.8v at the pins for the LEDS.

Transistor is 2n5306 PDF data sheet: http://www.experimentalistsanonymous.com/diy/Datasheets/2N5306.pdf

I have tried the transistor on a breadboard now, and still the same issue, unless I kick up the 5v to 8v but I still only get 3.3v tops out.

So did I misunderstand what this transistor would do? I am a neonate on this stuff. Thanks for the education.

How many of those transistors do you have ? This one might be broken.

This transistor has two transistors inside, it is called a 'darlington' transistor. Because it is a darlington transistor, the collector could be 1.4V, instead of 0.2V for normal transistors. The 'base' is not the wire in the middle, but on the side. Can you make a photo of it, so we can see the wiring ?

The 100 ohm to the base should be a higher value. If the Arduino is running at 5V, the resistor could be 10k. If the Arduino is running at 3.3V, the resistor could be 4k7

Do you use a single led with a resistor ? If you did not use a resistor, also the led might be broken.

You probably did.

Show a photograph or a correct schematic of what you built, or else explaining what is happening will mean guessing a lot.

Where do you plan to connect the LEDs ?

You should use this transistor to switch the low side of the power. So emitter to GND, LED cathode to collector, LED anode to resistor, other side of resistor to supply +. That's about all that can be told with the information you supplied yet.

So signal from the microcontroller after passing through the resistor goes to the 'base' leg on the transistor. This is 3.3v. The collector of the transistor has 5v to it, and surprisingly when the base activates the switch, I get only 2.8v at the pins for the LEDS.

Have you got the LED between the emitter and ground? If so that is your problem, you have what is known as an emitter follower arrangement and the maximum voltage you can get at the emitter is the voltage on the base minus 0.7V or so. Therefore the results you are seeing are bang on.

What you need to do is to wire your resistor and LED between the collector and 5V and connect the emitter to ground.

No I screwed this up and need to remake it. I did misunderstand.
Thanks.

No problem.
We like to see schematics and links and photos, and full sketches and so on. But if you get stuck, just ask. We let you know what we want we would like to know.

Wrong transistor, it has a Vsat of 1.4V at least, so 1A will dissipate 1400mW, the absolute maximum dissipation is exceeded by more than a factor of 2.

Use a logic level MOSFET.