Pumpmaster 5000

Project: 2018 - 2019

Writeup: May 2021

Freshly moistened

My small south-west-facing balcony cycles between scorching hot in the spring / summer to inhospitably barren and cold in the winter. There's no in-between. I thought I'd create a device to add "occasionally damp" to these characteristics.

Thought I'd keep it simple implementation-wise, so just went with a timer approach. In a proper solution, you'd probably do something cool with soil moisture / humidity / temperature tracking. But "just dump x liters of water per day" works fine for my little pots! I think I ran my perfboard prototype outside in a tupperware box for quite a few weeks until it got rained on and died. But it had passed proof-of-concept, so I started looking into a more permanent solution.

It's got a little flower on it. This is the final revision from 2019.

This was my first custom PCB for a project, but there's not much to it. It's just a carrier for an Arduino Mini (which I happened to have in stock) with terminals for all the IO. Took a few revisions to fix all of my amateur mistakes but EasyEDA / JLCPCB makes it all quite easy. These days I'd use JST connectors instead of screw terminals, I remember these being a particular pain in the ass when everything was all in.

The code used very dumb low-power mode sleeps to count up a timer and squirt for 30 seconds every six hours or something. I've been meaning to figure out Arduino interrupts but haven't ever gotten around to it! It was monitoring a float-valve in the reservoir as well as an override switch to allow a manual top-up if needed. The pump was a small 12V submersible pond pump which had plenty of power to fill up the ~3m of tube. It all got crammed into a "waterproof" project box with a whole load of silicone. I ran a 240V cable from inside under the squishy corner insulation of the balcony door to power the whole thing. (One day I'll do a self-contained system with a solar panel and a little battery. Would be cool)

Danglies

Version 1 used flexible tubing with holes haphazardly poked into it. To nobody's great surprise, this was useless. The water all came out around the nozzles and the lines sagged and went mouldy in the low spots which filled with water. But the setup all survived a year of solid pumping before I upgraded to V2 in 2019.

Mmmmm, roadside pollutomatoes

Version 2 got nice hard tubing and an upgraded enclosure. I could epoxy all the nozzles in properly this time so it directed way more water out onto the plants rather than trickling it all down the walls. It all looked a lot tidier! This time I hung the enclosure from the wall next to the reservoir (bin) to keep it out of the rain a bit more: the old enclosure was sitting on the floor and was filled with rusty water when I opened it up to turn it on again!

I'm still trying to work out how to keep anything at all alive on the desert balcony over the winter. I kinda want to try putting a plastic roof over the whole thing to make it a little greenhouse...