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...
Reply by Fred Bloggs●September 26, 20232023-09-26
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
Reply by boB●September 26, 20232023-09-26
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
Reply by Ralph Mowery●September 25, 20232023-09-25
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.
Reply by piglet●September 25, 20232023-09-25
On 24/09/2023 6:14 pm, Eddy Lee wrote:
> On Saturday, September 23, 2023 at 10:55:34 PM UTC-7, Jan Panteltje wrote:
>> On a sunny day (Sat, 23 Sep 2023 05:32:55 -0700 (PDT)) it happened Eddy Lee
>> <eddy7...@gmail.com> wrote in
>> <4da5b75c-8e11-4689...@googlegroups.com>:
>>> I often have to measure the difference of two 392V sources. Unfortunately, sometimes it become the sum, using a one-time fused
>>> muti-meter.
>>>
>>> I am thinking about using a rectifier diode (for direction) , 6V zener (for voltage), 6V 5W light bulb (for current) and 10 ohms
>>> resistor.
>>>
>>> Will it work? Perhaps 22 or 33 ohms resistor?
>> Specially for HV I bought a few dollar (5 USD or so) little analog multimeter after I blew up a digital one measuring a few kV in a PMT supply
>> https://panteltje.nl/pub/cheap_meter.jpg
>>
>> It does not seem to care much about voltage overload...
>
> I blew up a few of these, even for the older version with HV of 1000V. The newer one is 200V. Sometimes, the damage is not immediate. After a while, i got strange voltage readings.
>
> https://www.harborfreight.com/7-function-digital-multimeter-63759.html
So you can either buy a better meter rated to 1000V or build a resistor
10:1 attentuator and keep using cheap meters. Minimally use the meter
input impedance and just enough series resistance to get 10:1
piglet
Reply by Jan Panteltje●September 25, 20232023-09-25
On a sunny day (Sun, 24 Sep 2023 10:14:04 -0700 (PDT)) it happened Eddy Lee
<eddy711lee@gmail.com> wrote in
<3eaa7a30-a853-471a-b1af-405cb1ebbd6bn@googlegroups.com>:
>On Saturday, September 23, 2023 at 10:55:34 PM UTC-7, Jan Panteltje=
> wrote:
>> On a sunny day (Sat, 23 Sep 2023 05:32:55 -0700 (PDT)) it happened Eddy L=
>ee
>> <eddy7...@gmail.com> wrote in
>> <4da5b75c-8e11-4689...@googlegroups.com>:
>> >I often have to measure the difference of two 392V sources. Unfortunatel=
>y, sometimes it become the sum, using a one-time fused
>> >muti-meter.
>> >
>> >I am thinking about using a rectifier diode (for direction) , 6V zener (=
>for voltage), 6V 5W light bulb (for current) and 10 ohms
>> >resistor.
>> >
>> >Will it work? Perhaps 22 or 33 ohms resistor?
>> Specially for HV I bought a few dollar (5 USD or so) little analog multim=
>eter after I blew up a digital one measuring a few kV in a PMT supply
>> https://panteltje.nl/pub/cheap_meter.jpg
>>
>> It does not seem to care much about voltage overload...
>
>I blew up a few of these, even for the older version with HV of 1000V. The=
> newer one is 200V. Sometimes, the damage is not immediate. After a while=
>, i got strange voltage readings.
>
>https://www.harborfreight.com/7-function-digital-multimeter-63759.html
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.
Actually have an other analog one from ebay now:
https://www.ebay.com/itm/250977645828
But with 4 digital ones from ebay that I payed just a few dollars for (model was recommended by somebody here) I have
more meters than I need, some still in the box as spare.
https://panteltje.nl/pub/chinese_multimeter_img_3159.jpg
that was the one I fixed the 900 Ohm in...
Used every day, but does not like HV.
[
Reply by Eddy Lee●September 24, 20232023-09-24
On Sunday, September 24, 2023 at 7:00:48 PM UTC-7, Jasen Betts wrote:
> On 2023-09-23, Eddy Lee <eddy7...@gmail.com> wrote:
> > On Saturday, September 23, 2023 at 3:59:57 PM UTC-7, whit3rd wrote:
> >> On Saturday, September 23, 2023 at 11:37:49 AM UTC-7, Eddy Lee wrote:
> >> > On Saturday, September 23, 2023 at 10:49:20 AM UTC-7, whit3rd wrote:
> >> > > On Saturday, September 23, 2023 at 5:33:01 AM UTC-7, Eddy Lee wrote:
> >> > > > I often have to measure the difference of two 392V sources. Unfortunately, sometimes it becomes the sum, using one-time fused muti-meter.
> >> > > >
> >> > > > I am thinking about using a rectifier diode (for direction) , 6V zener (for voltage), 6V 5W light bulb (for current) and 10 ohms resistor.
> >> > > >
> >> > > > Will it work? Perhaps 22 or 33 ohms resistor?
> >> > > Or maybe a 220k ohm resistor and a neon lamp?
> >> > Did it light up well between 3V and 12V? I can tell when there is around 3V across the 6V light bulb.
> >> There's some crude multilamp variants that can tell 120VAC from 240 from 480...
> >> it gives enough info to rethink what meter (or meter setting) to use for the real
> >> measurement thereafter. Neon doesn't glow at under 50V or so.
> >>
> >> That relatively high strike voltage is how it can give a good glow indication off
> >> high voltages without drawing much current, using no battery.
> >
> > But what I want is to tell the difference between two 392V sources, usually +/- 12V floating on top of 392V. However, sometimes it get mis-wired into sum, or 784V. In that case, it's OK to blow the bulb like a fuse.
> a 6V lamp on 700V will probably blow like a 12V fuse does in the same
> circumstance (explosively), I suspect you would say not ok.
I blew one at around 10V, the filament vaporized but the glass container is OK. There was a bright flash, but no explosion.
> Just buy a 1000V auto-ranging multimeter, with whatever measurement
> catergory is suited to traction batteries (I'm guessing probably
> Cat.IV )
I got one, but how do we know that it's really safe for 784V.
On 2023-09-23, Eddy Lee <eddy711lee@gmail.com> wrote:
> On Saturday, September 23, 2023 at 3:59:57 PM UTC-7, whit3rd wrote:
>> On Saturday, September 23, 2023 at 11:37:49 AM UTC-7, Eddy Lee wrote:
>> > On Saturday, September 23, 2023 at 10:49:20 AM UTC-7, whit3rd wrote:
>> > > On Saturday, September 23, 2023 at 5:33:01 AM UTC-7, Eddy Lee wrote:
>> > > > I often have to measure the difference of two 392V sources. Unfortunately, sometimes it becomes the sum, using one-time fused muti-meter.
>> > > >
>> > > > I am thinking about using a rectifier diode (for direction) , 6V zener (for voltage), 6V 5W light bulb (for current) and 10 ohms resistor.
>> > > >
>> > > > Will it work? Perhaps 22 or 33 ohms resistor?
>> > > Or maybe a 220k ohm resistor and a neon lamp?
>> > Did it light up well between 3V and 12V? I can tell when there is around 3V across the 6V light bulb.
>> There's some crude multilamp variants that can tell 120VAC from 240 from 480...
>> it gives enough info to rethink what meter (or meter setting) to use for the real
>> measurement thereafter. Neon doesn't glow at under 50V or so.
>>
>> That relatively high strike voltage is how it can give a good glow indication off
>> high voltages without drawing much current, using no battery.
>
> But what I want is to tell the difference between two 392V sources, usually +/- 12V floating on top of 392V. However, sometimes it get mis-wired into sum, or 784V. In that case, it's OK to blow the bulb like a fuse.
a 6V lamp on 700V will probably blow like a 12V fuse does in the same
circumstance (explosively), I suspect you would say not ok.
Just buy a 1000V auto-ranging multimeter, with whatever measurement
catergory is suited to traction batteries (I'm guessing probably
Cat.IV )
--
Jasen.
🇺🇦 Слава Україні
Reply by Fred Bloggs●September 24, 20232023-09-24
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.
Reply by whit3rd●September 24, 20232023-09-24
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.