I have started working on my next two projects. UniPowerSupply is the simplest. I’m working on a universal power supply using an LM2576 IC. The basic idea is to be able to use any power source under 60V to generate a stable 5v DC source. Moving forward I’ll retire the USB-B power input and use this design. It should be a net wash and increase component count slightly. There are other voltage regulation IC’s out there, but this one has a wide input range and is very efficient with a switching core.
The second project is RO Saver. I am taking the TinyPLC Duo aka TinyTimer Duo and building an application specific version of it for Reverse Osmosis. It will control two sprinkler valves and feature an input. The input is designed for a float switch. The output will be relays to run 24VAC sprinkler valves. I may add a 3rd channel to it to control a booster pump as well. A booster pump can increase efficiency to nearly 50% in a two stage RO system. The idea is that the board will run for 5 minutes per hour or when the float switch indicates a low water level. The 2nd channel will be used to run a membrane flush valve once per period. The period may be net-run time on the membrane or once per day. I like the run-time option because it simplifies maintenance. I will probably include an option that allows bypassing the periodic run in favor of a float switch. I may also include an option to set the run duration with a jumper or dip-switch or a resistor. The idea is to alleviate the need for programming and make it more of a gadget. Once RO Saver is completed it will become a kick-starter project. This will build on the lessons learned from TinyTimer and improve the on-time performance.
I will also be designing a programming chassis to simplify the need to burn a number of Arduino and ATTiny85 chips. It will essentially be a PCB with a ZIF socket and an ISP header.