I have build a circuit as follow. From 5V a 220 Ohm resistor to a LED to a 2N3904 transistor to 0V. The base of the transistor is connected to a 10K Ohm resistor to a switch to 5V.
When I measure the voltage across the transistor from collector to emitter with the switch open I measure 3.43V and with the switch closed 73.4mV.
From what I have read I expected a somewhat higher voltage drop with the switch closed. Is this low voltage to be expected with a circuit like this?
And the part I don't get is why I measure 3.43V with the switch open. Also with the switch open I measure 3mV over the LED and 0V over the resistor. That doesn't match the 4.98V measured from ground to +5V. Is my voltmeter affecting what I am reading?