National Semiconductor has a high voltage application note in the PDF which
describes the product.

Or you could use an opto-isolator (an analog version like the HCNR200) to
read the voltage across a shunt. You will need a drive transistor because
the usual opamp suspects won't be able to provide enough current for a LED
bargraph.

"Patrick" wrote in message
...
Hi all,

I started a new amplifier project, a 4CX1500B 2m amplifier.
Wanting to make it a bit more state of the art, i want to replace the
old meters by Led bars...
The simplest way to do that is to use a LM3914 bar display which can
measure voltages with a ground reference.

My design will use a cathode driven, DC grounded screen. So measures
must be make "floating" as the ref is the cathode .

How can i achieve this in a simple way ??

73, Patrick TK5EP
http://tk5ep.free.fr