avr_fred:
While I cannot point you to a specific tutorial, the most important part of wiring power is to get the polarity correct. Perhaps it is time to purchase a low cost digital multimeter. Using the multimeter, you can (safely) confirm connections and polarities before applying power to a circuit. As you grow with the hobby, a multimeter will become your most basic troubleshooting tool.A $5 cheap-o from Harbor Frieght is perfectly fine for Arduino related work but please don't use the cheap Chinese meters on household voltage, they're not super safe, is especially the probes.
I did.
I had an old multimeter which I did not trust the reading, so last week, I bought an: AstroAI Digital Multimeter, TRMS 6000.
avr_fred:
As an side note about polarity, the Trinket has a diode on the VBAT input connection. This prevents any damage to the board if it is connected to reverse polarity since current can only flow one way through a diode, the plumbing analog of a check valve.
Looking at this pinout diagram:
I'm guessing that the VBAT input connection is the top right one above the ground (labeled: BAT+)
avr_fred:
But, if you use 3 batteries for a 4.5 volt supply and connect it to the +5V connection, there is no diode.
...
I'm not sure which input you're talking about here ???
avr_fred:
...as the diode causes a small drop in voltage, only about 0.3 volts, but that could represent hours to days of run time with a battery.
Oh!! Hence why they advise 5.5V min on it. Coz of the voltage drop...
avr_fred:
LR44: unsuitable, too low in power delivery ability. A CR2032 is about the minimum for a disposable cell.
I was thinking using multiple LR44 in serie...
But considering the CR2032 is 3V, it may be better to use 2 CR2032 in serie to get sufficent voltage to the arduino.