Voltage regulation circuit 12V to 5V in 5A range

[Demon]

I could be wrong but the way I read your instruction sheet I see this..... think the module has the dimmer mechanism internal and is controlled by 0-5 volt on the Vo pin

Yeah, as I corrected myself in post #38,
https://www.picbasic.co.uk/forum/sho...583#post156583
it's the backlight that I'm controlling.

This is white-on-black LCDs. I've set V0 to a "visually acceptable level" (still have to test Richard's suggestion), and I control the brightness of the LCDs only with the backlight.