This is a neat challenge from Public Lab user cfastie who made this cute low-power timer for data-logging projects, mounting a DIP6 IC on a DIP8 adapter, using the other adapter pads for additional connections – neat! They even mention our own TPL5110 breakout for comparison; the adapter used is already quite smaller than our own breakout size (with a few fewer features sacrificed) and they conclude they could further minify their own design using smaller resistor/s than those shown above.
Adding a low power timer to a data logger has great promise as an easy way to extend the time the logger can operate on small batteries. Rough calculations suggest that a few AA batteries can power an Arduino-based logger for a year or more when a TLP5110 timer controls the current flowing to the logger.
The Adafruit Low Power Logger costs $4.95 (plus shipping) which adds a substantial proportion to the cost of a DIY Arduino-based data logger. So I investigated making my own timer using the same components. The only components needed are the TPL5110 timer IC, a mosfet, and a resistor. Not including shipping, these cost $1.25 per set if you buy 10 of each. So I did.
One of my DIY timers was controlling a Mini Pearl Logger in my freezer the other day. A 61.9kΩ resistor set the logging interval at 12 minutes. The graph includes 10 hours of data. My freezer temperature varies a lot more than I thought it would.
