Yeh I have gone down the same track some months ago.
Designed and built this one from scratch.
It is regulated by 2 x LM317t volt regs to vary the current, and has 2 x 555 timers to take care of charger timing, all selectable with rotary switches. You can see the volt regs hanging off the side on the heat sinks.
It can slam charge or charge more sedately and (obviously) does two bits at once, so you can charge two cars at different voltages at the same time, eg a normal bit and a dual or triple cell.
Havent used a controller to charge my bit for a long time now, and the other good thing is that controller batteries last for ages when you dont use them for charging.
uA