Turns out I might by lying about the Jaycar panel meter.
Looking back, I found a picture with a 7805 I used to power it.

It's a 10 bit ADC I think since it's a 16f876.
I have it working as far as it returns 0 if the ADC line is grounded,
and 255 if It's connected to the pic circuit's 5 Volt power.

Re: your link, I've seen many 5 Volt Voltmeter circuits on the net,
but this is to operate in the range of 12 Volt batteries.
I've found a few hints about that on other forums.. ie:
Ok, so you've decided on 0.1V resolution. Set the A-D ref volt to 5V and construct a voltage divider on the A-D input with a mid-point voltage of 5V when 25.5V is applied at the top-end e.g 15k fixed resistor at the top, 10k multi-turn pot at the bottom and take the output off the wiper. (you can refine this but just as an example)

I believe the PIC has a 10-bit A-D converter so RRF the result to give an 8-bit result. You now have a 0-25.5V voltmeter with a 0.1V resolution and a direct relationship between the value returned by the A-D and the input voltage i.e. 125 = 12.5V, 147 = 14.7V ....
I have sound now, and an I2C EEPROM for logging. I'm just ready now to play with voltage dividers
to prepare a voltage input.