Well, I have a problem now.
After going through the Datasheet again, I need to either give it the correct voltage or at least close to 80%. In other words, these 5 volt relays require a minimum of 4volts before it can do anything.
It was so sad last night when I rushed back home to test the 5volt relay, knowing full well of the end result. But I still had to try. The voltage from the 3.7volt Lipo failed to activate it while the 5volts from a USB battery source kept the relay clicking merrily.
Coming back to my theoretical circuit which runs off 3.7volts from a LiPo, this is not going to happen. I can search for the more expensive and the very elusive 4.5volts version which only requires a minimal 3.68volts. But after calming the f**k down, getting the 3volts version is a much saner choice. This way, I only need to use a resistor to get the voltage I needed to get these guys to do their job.
To be honest, I really want to keep this part of the circuit with a minimal component count as I can since I would be hand soldering them. I won’t claim to be lazy on this but sometimes, I really need to get into the mood to do so much soldering and stop thinking about the only slave left in an urban sweat shop. Anyway, just to activate this relay, I can just connect it directly to the control source with the current limiting resistor as the only ‘protection’. So, in the end, I would need additional resistors, a NPN Transistor, and one flyback diode.
