Hi guys
So I have a project that automates a functional test of a product at work. One portion of the test is to use a relay and came across this video and I have drawn it out as a schematic as shown below:
The "LS1" port on the left is connected to the arduino and the relay is connected to the product. Vcc is connected to the 5Vdc on the arduino.
According to the datasheet of the relay, the nominal current to switch on is 71.4mA. I'm using the elegoo
arudino uno and the maximum current draw is 40mA, their SunFounder board can draw 50mA. Here are my questions
- On the collector side, it is connected to the 5Vdc of the controller, with the maximum current draw possible at 40mA for the elegoo and 50mA for the board they are using and the nominal current needed to drive the relay is 71.4mA, I cannot get my head around the fact they can make it work without an external power supply that is capable of drawing 71.4mA or above
- Since I know the load requirement for my relay, how do I use the transistor datasheet to calculate what my base current should be (or gain)? In the datasheet they listed out the gain and a certain operating conditions, but what if my condition is outside of that?
- In this application of the transistor, can I using it as an amplifier or a switch? to me it is a switch, but not sure
- I have read some articles around saying if I am intending to use it as a switch, then you want to operate your transistor in the saturation state, which make the transistor a short between collector and emitter. Does the gain value at saturation play any role in amplifying current?
Sorry for the long questions, being reading on how to in-cooperate transistors in the circuit and it is so confusing and datasheet is confusing even more, thanks guys!
Datasheet: