Obviously I need a regulator, and as I am making these up using a milling machine, a small self contained module I can solder on to a PCB as a single component is the obvious choice. Back to Amazon, and I find something simple and cheap :-
It has three 0.1" pitch leads, and so easily mounts on the PCB. It has an offset with a header as it has components both sides. Works well though.
However, I noticed it gets a bit warm. Not really a huge surprise, but even when just powering from 5V in my Galaxy keypad design it still is a touch warm.
So I did a bit more research and found these tiny switch mode supplies, Pololu D24V5F3. A few pounds more expensive, also available from Amazon, but really really nice:-
- Still a very small design 0.4" by 0.5" (yes, bloody inches!).
- Components only one side, so can mount flush to my PCB making easy for something like an ESP-01 to fly over it and save more space.
- Cool. I mean really cool. They say 2mA, and given that my ESP-12F plus RC522, running off 12V on one of these is 30mA total, I am impressed. I was seeing 140mA previously.
- It also has a shutdown input - which I suspect I could use with a button on a battery powered device so you can power up and then have s/w power down. I wonder if I can even do something clever with sleep mode on an ESP8266 shutting down its own power while it sleeps - may need a capacitor somewhere in that :-)
- Will accept from around 3.5V up to 36V as input!
- They do other voltages, and current ratings as well, and step-up regulators.
|Actually a D24V6F3, the D24V5F3 are on order|
Basically, I am working through the total maze of too much information trying to weed out the good from the bad and work out what sort of components are good. I think this comes in to the "good" category for voltage regulator.