"I was disappointed in one of my approaches to make a digital switch, where i used a NPN transistor with 5vdc from Collector and 3.45 vdc from arduino to BASE, i had my load at the emitter, i did manage to get a good amount of current but the voltage was still not to my expectation,"
How did you wire that up?
Generally an NPN is wired as an Open Collector circuit. The source voltage goes thru a pullup resistor to the collector.
When the NPN base is low, the collector is pulled up by the resistor, with the current available determined by the resistor.
When the NPN base is driven high, the collector pulls the signal low, down to about 0.7V if the emitter is grounded.
Typically PNPs (or P-channel MIOSFET), or a pullup resistor, are used to source current (and provide a high voltage) and NPNs (or N-channel MOSFET) are used to sink current (and cause a low voltage).