HV indicator...

[Ralph Mowery]

In article <uer5hr$iuap$1@solani.org>, alien@comet.invalid says...

Yea, I do not keep it connected for any length of time though...
And PMT circuits do not have a high current capability.
I blew up a nice digital one that was accidently on the Ohms range a few weeks ago
I expected the chip was dead, but investigation found just a 900 Ohm SMD resistor open circuit.
I replaced it by 680 and 220 Ohm in series... Reading is perfect again...
How I found out it should be 900 Ohm? divider circuit measured (with an other meter of course)
90 ? 9000 etc, so that in-between range had to be be 900.

When working I often used a Fluke t-1000. That was a good test meter if
you do not need too much resolution. It is almost blow out proof. I
often put it on the ohms scale and put it across fuses on a 480 volt 3
phase system that was under power.

I do not recall the number of it, but liked to use one of the Flukes
that just had a row of LEDs. You could put it across a live circuit
and if under power it would light up the leds to indicate how much
voltage and if no powre but low ohms another led wold light.

 

[boB]

On Sun, 24 Sep 2023 14:00:48 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Sunday, September 24, 2023 at 4:17:02?PM UTC-4, whit3rd wrote:
On Sunday, September 24, 2023 at 5:40:16?AM UTC-7, Fred Bloggs wrote:

Some multimeters, in particular EXTECH, have a Non-Contact Voltage (NCV) Detector in the form of an ionizing gas bulb that lights for VAC in the range 100-600 Volts AC.

These are available in the big box stores off the shelf / display hook.

https://www.flir.com/products/ex330/
My Greenlee GT-11 non contact detector is a capacitive pickup and lights an LED; it
only senses AC.

Greenlee? You don\'t mess around, that\'s one of the best out there.

How about a neon lamp, a resistor and a capacitor ?

It will flash faster at higher voltage. Double the voltage should be
easy-ish to distinguish from 1/2 that voltage.

boB

 

[Fred Bloggs]

On Tuesday, September 26, 2023 at 2:31:30 PM UTC-4, boB wrote:

On Sun, 24 Sep 2023 14:00:48 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Sunday, September 24, 2023 at 4:17:02?PM UTC-4, whit3rd wrote:
On Sunday, September 24, 2023 at 5:40:16?AM UTC-7, Fred Bloggs wrote:

Some multimeters, in particular EXTECH, have a Non-Contact Voltage (NCV) Detector in the form of an ionizing gas bulb that lights for VAC in the range 100-600 Volts AC.

These are available in the big box stores off the shelf / display hook.

https://www.flir.com/products/ex330/
My Greenlee GT-11 non contact detector is a capacitive pickup and lights an LED; it
only senses AC.

Greenlee? You don\'t mess around, that\'s one of the best out there.
How about a neon lamp, a resistor and a capacitor ?

As in relaxation oscillator? That\'s not a bad idea.

It will flash faster at higher voltage. Double the voltage should be
easy-ish to distinguish from 1/2 that voltage.

Yep.

boB

 

[whit3rd]

On Tuesday, September 26, 2023 at 11:31:30 AM UTC-7, boB wrote:

How about a neon lamp, a resistor and a capacitor ?

It will flash faster at higher voltage. Double the voltage should be
easy-ish to distinguish from 1/2 that voltage.

Yep, but you can also use multiple neon lamps and just hang each on a
resistor divider instead of current-limit resistor.

The divider ratio determines whether the AC peak crosses the strike threshold
of the (presumed identical) lamps. Just scribble an AC calibration next to
each light...