Hello,
1 and 7 channels have available software source codes. Multi-language support. flower watering, garden watering, light-on, motor control, etc. Can be used in many projects.
https://youtu.be/p5ZEiKV24qs07:00 Detailed information about the circuit
04:09 Information about settings
09:49 Test for 7 channels
11:36 Multi-channel test
12:49 Circuit diagram, PCB drawing
13:05 Language change from software
Source:
http://picsource.com.br/archives/7414
A commercial unit that does all kinds of sprinkler related stuff including networking so I can control the unit from my iPad all via wifi. It's very handy. I thought to build one but for $100, I can't build up any enthusiasm.
https://www.amazon.com/Orbit-57950-12-Station-Controller-Compatible/dp/B01D15HOTU
Hello @rstofer,
Very good controller thanks. $100 big money (my country ) here is the cheapest DIY

update Orbit 57950 B-hyve Smart 12-Zone Indoor/Outdoor Sprinkler Controller price $115.54
The OP's device, beyond being DIY, has the benefit of not being "connected".
The OP's device, beyond being DIY, has the benefit of not being "connected". 
Ops..
still source code can be improved