I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1

Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so.
I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and
I will need to see a confirmation of that sort of low current use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can anyone
who is conversant with such things and knows the suppliers help?

Bill

williamwright wrote:

It would be perfectly OK for the voltmeter and
ammeter to be separate units.

https://toolstoday.co.uk/sealey-automotive-current-tester-30a

they do cheaper ones for 20A rather than 30A, but they only have the
fuse-blade hardwired, no croc-clips

After serious thinking williamwright wrote :
I've looked all over. I must be looking in the wrong places. Can anyone who
is conversant with such things and knows the suppliers help?

-2 0 +2 then make a parallel shunt resistor to calibrate it accurately?

In use, multiply readings by 10x.

On 05/09/2020 17:52, williamwright wrote:
I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1


Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so.
I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and
I will need to see a confirmation of that sort of low current use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can anyone
who is conversant with such things and knows the suppliers help?

Bill

Any good? Delivery Monday £12

https://www.amazon.co.uk/KETOTEK-Amm...dp/B07PHK7KFH/

On 05/09/2020 19:05, Andy Bennet wrote:
On 05/09/2020 17:52, williamwright wrote:
I've been ages searching and I can't find what I want, though it
sounds so simple. It's a digital ammeter/voltmeter combination. The
max voltage to be read is 16VDC; the max amps to be read is 20A. The
supply voltage is nominally 12VDC. It would be perfectly OK for the
voltmeter and ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1


Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say
so. I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle,
and I will need to see a confirmation of that sort of low current
use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can
anyone who is conversant with such things and knows the suppliers help?

Bill

Any good? Delivery Monday £12

https://www.amazon.co.uk/KETOTEK-Amm...dp/B07PHK7KFH/


Thats not bad, it does also simplify the wiring involved with putting
two meters and its one hole to cut inatead of two!

S.

On 05/09/2020 18:53, Andy Burns wrote:
williamwright wrote:

It would be perfectly OK for the voltmeter and ammeter to be separate
units.

https://toolstoday.co.uk/sealey-automotive-current-tester-30a

they do cheaper ones for 20A rather than 30A, but they only have the
fuse-blade hardwired, no croc-clips

Ah, I should have said I need panel meters!

Bill

On Saturday, 5 September 2020 20:37:26 UTC+1, williamwright wrote:
On 05/09/2020 18:53, Andy Burns wrote:
williamwright wrote:

It would be perfectly OK for the voltmeter and ammeter to be separate
units.

https://toolstoday.co.uk/sealey-automotive-current-tester-30a

they do cheaper ones for 20A rather than 30A, but they only have the
fuse-blade hardwired, no croc-clips

Ah, I should have said I need panel meters!

Bill

Oh, then you'll need 2 separate meters. Don't overlook the possibility of converting an ammeter into either type you want. Or add switching so you only need one.


NT

On 05/09/2020 19:05, Andy Bennet wrote:

Any good? Delivery Monday £12

https://www.amazon.co.uk/KETOTEK-Amm...dp/B07PHK7KFH/


Thanks for that. I had seen it and discounted it as unnecessarily
complicated (Watts!) but I shall think again! It would fit the bill I
think, unless someone comes up with something better.

Bill

On 05/09/2020 19:05:03, Andy Bennet wrote:
On 05/09/2020 17:52, williamwright wrote:
I've been ages searching and I can't find what I want, though it
sounds so simple. It's a digital ammeter/voltmeter combination. The
max voltage to be read is 16VDC; the max amps to be read is 20A. The
supply voltage is nominally 12VDC. It would be perfectly OK for the
voltmeter and ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1


Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say
so. I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle,
and I will need to see a confirmation of that sort of low current
use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can
anyone who is conversant with such things and knows the suppliers help?

Bill

Any good? Delivery Monday £12

https://www.amazon.co.uk/KETOTEK-Amm...dp/B07PHK7KFH/

That looks very nice, having a remote shunt at the point of measurement
is a nice feature.

This where we mourn the loss of Tandy on the high street. They used to stock
the sort of things that vehicle customisers wanted, though in them there
days they were mostly analogue of course.

Brian

--
--
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
wrote in message
...
On Saturday, 5 September 2020 20:37:26 UTC+1, williamwright wrote:
On 05/09/2020 18:53, Andy Burns wrote:
williamwright wrote:

It would be perfectly OK for the voltmeter and ammeter to be separate
units.

https://toolstoday.co.uk/sealey-automotive-current-tester-30a

they do cheaper ones for 20A rather than 30A, but they only have the
fuse-blade hardwired, no croc-clips

Ah, I should have said I need panel meters!

Bill

Oh, then you'll need 2 separate meters. Don't overlook the possibility of
converting an ammeter into either type you want. Or add switching so you
only need one.


NT

In uk.d-i-y williamwright wrote:
I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1

Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so.
I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and
I will need to see a confirmation of that sort of low current use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can anyone
who is conversant with such things and knows the suppliers help?

It's not something that you'll get 'off the shelf' I don't think. You
*might* find something in the [small] boat electronics field but it
will probably cost an arm and a leg - boat stuff always does.

Take a look at:-
https://www.asap-supplies.com

All my boat electronics are 'home made' though. I use a BeagleBone
Black single board computer. The voltmeters are just simple voltage
dividers feeding into ADC inputs. The ammeters are hall effect
devices, they really are the best way to measure (fairly large)
currents nowadays. You can get ready made transudcers, things like
this:-
https://shop.pimoroni.com/products/a...ier-30a-to-30a

--
Chris Green
·

I actually threw out an old ammeter when I cleared the shed. It was made by
Westinghouse, and was a bit retro looking with a kind of curved bit of case
for one connection that pushed against the metal car body as you did up a
clamp and there was a screw for the other end. Now it was centre zero and
the needle was very bouncy indeed.. I originally got it from a bloke who
fitted it to his sports car, but found it totally unusable due to the bounce
in the needle making measurements totally useless.
Stupid design.
Brian

--
--
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Chris Green" wrote in message
...
In uk.d-i-y williamwright wrote:
I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1

Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so.
I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and
I will need to see a confirmation of that sort of low current use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can anyone
who is conversant with such things and knows the suppliers help?

It's not something that you'll get 'off the shelf' I don't think. You
*might* find something in the [small] boat electronics field but it
will probably cost an arm and a leg - boat stuff always does.

Take a look at:-
https://www.asap-supplies.com

All my boat electronics are 'home made' though. I use a BeagleBone
Black single board computer. The voltmeters are just simple voltage
dividers feeding into ADC inputs. The ammeters are hall effect
devices, they really are the best way to measure (fairly large)
currents nowadays. You can get ready made transudcers, things like
this:-

https://shop.pimoroni.com/products/a...ier-30a-to-30a

--
Chris Green
·

In article ,
williamwright wrote:
I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

Ones designed for car use are normally 20 amp - but being more specialist
units, rather more pricey than a basic one. And usually do things like
dwell and RPM etc. I keep one of those in the old car.

The snag with using a DVM to measure high current is they are normally
fuse protected. And inrush current can cause that fuse to blow - and it
may not be a standard cheap fuse.

For higher currents, a clip on type may be better - but more expensive and
tricky to get an accurate one to measure DC current.

Another way is to get a suitable shunt with leads and crock clips etc
(perhaps build it yourself?) and use an ordinary DVM across it. You'd
obviously need to make a calibration table. Or trim the size of the shunt.
A length of ally would what I'd try - and file the width down to calibrate.

--
*The most wasted day of all is one in which we have not laughed.*

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
williamwright wrote:
On 05/09/2020 18:53, Andy Burns wrote:
williamwright wrote:

It would be perfectly OK for the voltmeter and ammeter to be separate
units.

https://toolstoday.co.uk/sealey-automotive-current-tester-30a

they do cheaper ones for 20A rather than 30A, but they only have the
fuse-blade hardwired, no croc-clips

Ah, I should have said I need panel meters!

Ah - old fashioned analogue?

--
*The first rule of holes: If you are in one, stop digging!

Dave Plowman London SW
To e-mail, change noise into sound.

On 06/09/2020 11:19, Dave Plowman (News) wrote:
In article ,
williamwright wrote:
On 05/09/2020 18:53, Andy Burns wrote:
williamwright wrote:

It would be perfectly OK for the voltmeter and ammeter to be separate
units.

https://toolstoday.co.uk/sealey-automotive-current-tester-30a

they do cheaper ones for 20A rather than 30A, but they only have the
fuse-blade hardwired, no croc-clips

Ah, I should have said I need panel meters!

Ah - old fashioned analogue?


At this time of year there are (were) usually auto-jumbles all over
the place where old vehicle ammeters can be found.

On 05/09/2020 17:52, williamwright wrote:
I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1


Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so.

Judging by the many on Ebay I assume it be 0 to 15 and not 15-0-15.
Most(all) don't seem to have any display ability for a -ve indication.

Perhaps consider a cheap 0 to 20V panel meter for your Voltage display

and then find a -199.9mV 0 +199.9mV voltage meter for your Ammeter by
adding your own external shunt of the appropriate value to make the
+/-199.9V = +/-19.99Amps

Looking on Ebay the only combined meters that meet your requirement for
centre zero amps appear to use a hall effect sensor where you need to
pass the wire through the sensing ring

example
https://www.ebay.co.uk/itm/UK-Digita...0AAOSwc01fH-4Y

or

https://tinyurl.com/y4gxtfwg



I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and
I will need to see a confirmation of that sort of low current use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can anyone
who is conversant with such things and knows the suppliers help?

Bill


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

"williamwright" wrote in message ...

I've been ages searching and I can't find what I want, though it sounds
so simple. It's a digital ammeter/voltmeter combination. The max voltage
to be read is 16VDC; the max amps to be read is 20A. The supply voltage
is nominally 12VDC. It would be perfectly OK for the voltmeter and
ammeter to be separate units.

I found a product priced at around £20, which seems a bit cheap to me,
but delivery is 20th - 29th Oct, and it only reads up to 15A

https://www.amazon.co.uk/KIMISS-Digi.../dp/B07G382BR1

Well, 15A would be OK at a pinch, but I can't wait until 20th Oct.
I'm assuming the ammeter is 15-0-15 as well, although it doesn't say so.
I do need centre zero.
I do have a 30-0-30 analogue meter but 2A scarcely moves the needle, and
I will need to see a confirmation of that sort of low current use/charge.

I don't want a hall effect device; I want something with a shunt.

I've looked all over. I must be looking in the wrong places. Can anyone
who is conversant with such things and knows the suppliers help?

-----------------------------------------------------------------------------------------------------------------------------------------

Try CPC - their prices are competitive

https://cpc.farnell.com/c/electrical...earchlookahead


Otherwise try RS Components or Farnell

On 06/09/2020 12:03, alan_m wrote:

and then find a -199.9mV 0 +199.9mV voltage meter for your Ammeter by
adding your own external shunt of the appropriate value to make the
+/-199.9V = +/-19.99Amps

Further reading of some data sheets about using a shunt with a centre
zero voltmeter suggest that the power supply for the panel meter
may/will have to be isolated from that used for the current through the
shunt. In a DMM this is easily achieved by using a PP3 battery as the
power source.

In these modules this may be easily achievable by using a dc to dc
converter that isolates output from input to supply the panel meter's
power. This would allow the one source of power to be used such as using
a car battery as the power source with the meter (with additional dc to
dc converter) measuring both the charge and discharge current.

See pages 15 and 16
https://www.lascarelectronics.com/me...tion-notes.pdf


LCD
https://www.lascarelectronics.com/di...nel-meters/lcd
(prices from around £15)

LED
https://www.lascarelectronics.com/di...nel-meters/led

When selecting individual modules in the above links there is a data
sheet link on the right hand side of the page and towards the end of the
sheet some application notes.

Possibly the reason for cheap centre zero digital ammeters having a hall
effect sensor is the ease of isolation between the meters power supply
and the current being measured.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 06/09/2020 15:00, John wrote:

Try CPC - their prices are competitive

https://cpc.farnell.com/c/electrical...earchlookahead


Thanks. I might end up using a CPC voltmeter. But they don't have a
suitable centre zero ammeter.


Otherwise try RS Components or Farnell


Farnell is CPC but with higher prices isn't it?

Bill

williamwright wrote:
On 06/09/2020 15:00, John wrote:

Try CPC - their prices are competitive

https://cpc.farnell.com/c/electrical...earchlookahead



Thanks. I might end up using a CPC voltmeter. But they don't have a
suitable centre zero ammeter.


Otherwise try RS Components or Farnell


Farnell is CPC but with higher prices isn't it?

Bill


Farnell is dearer, but carries a *much* larger range. Both owned by Avnet.

On 06/09/2020 20:39, Tweed wrote:
williamwright wrote:
On 06/09/2020 15:00, John wrote:

Try CPC - their prices are competitive

https://cpc.farnell.com/c/electrical...earchlookahead



Thanks. I might end up using a CPC voltmeter. But they don't have a
suitable centre zero ammeter.


Otherwise try RS Components or Farnell


Farnell is CPC but with higher prices isn't it?

Bill


Farnell is dearer, but carries a *much* larger range. Both owned by Avnet.


I think Farnell has big discounts for certain customers.

Bill

williamwright wrote:
On 06/09/2020 20:39, Tweed wrote:
williamwright wrote:
On 06/09/2020 15:00, John wrote:

Try CPC - their prices are competitive

https://cpc.farnell.com/c/electrical...earchlookahead



Thanks. I might end up using a CPC voltmeter. But they don't have a
suitable centre zero ammeter.


Otherwise try RS Components or Farnell


Farnell is CPC but with higher prices isn't it?

Bill


Farnell is dearer, but carries a *much* larger range. Both owned by Avnet.


I think Farnell has big discounts for certain customers.

Bill


They offer 15% discount to the higher education sector, and anything
purchased in significant quantity is subject to negotiation.

After serious thinking Brian Gaff (Sofa) wrote :
I actually threw out an old ammeter when I cleared the shed. It was made by
Westinghouse, and was a bit retro looking with a kind of curved bit of case
for one connection that pushed against the metal car body as you did up a
clamp and there was a screw for the other end. Now it was centre zero and the
needle was very bouncy indeed.. I originally got it from a bloke who fitted
it to his sports car, but found it totally unusable due to the bounce in the
needle making measurements totally useless.
Stupid design.

A bi-polar cap across the movement would smooth that out.

Dave Plowman (News) used his keyboard to write :
Another way is to get a suitable shunt with leads and crock clips etc
(perhaps build it yourself?) and use an ordinary DVM across it. You'd
obviously need to make a calibration table. Or trim the size of the shunt.
A length of ally would what I'd try - and file the width down to calibrate.

On a car, you can put your meter end to end across the main battery
thick cable, using that as the shunt. You can calibrate the meter using
a resistance in series with the meter.

On 08/09/2020 11:46, Harry Bloomfield wrote:
Dave Plowman (News) used his keyboard to write :
Another way is to get a suitable shunt with leads and crock clips etc
(perhaps build it yourself?) and use an ordinary DVM across it. You'd
obviously need to make a calibration table. Or trim the size of the
shunt.
A length of ally would what I'd try - and file the width down to
calibrate.

On a car, you can put your meter end to end across the main battery
thick cable, using that as the shunt. You can calibrate the meter using
a resistance in series with the meter.

Not exactly corrected for temperature and not ideal unless you do it
AFTER the starter motor takeoff


--
Outside of a dog, a book is a man's best friend. Inside of a dog it's
too dark to read.

Groucho Marx

In article ,
Harry Bloomfield wrote:
Dave Plowman (News) used his keyboard to write :
Another way is to get a suitable shunt with leads and crock clips etc
(perhaps build it yourself?) and use an ordinary DVM across it. You'd
obviously need to make a calibration table. Or trim the size of the
shunt. A length of ally would what I'd try - and file the width down
to calibrate.

On a car, you can put your meter end to end across the main battery
thick cable, using that as the shunt. You can calibrate the meter using
a resistance in series with the meter.

Maplin did just such a kit many years ago. Measuring the voltage drop
across the main ground - battery to chassis. It had several modes - but
one was driving a tri-colour LED. Red for discharge, green for charge,
amber for the load just balanced.

--
*Vegetarians taste great*

Dave Plowman London SW
To e-mail, change noise into sound.

Brian Gaff (Sofa) wrote:
I actually threw out an old ammeter when I cleared the shed. It was made by
Westinghouse, and was a bit retro looking with a kind of curved bit of case
for one connection that pushed against the metal car body as you did up a
clamp and there was a screw for the other end. Now it was centre zero and
the needle was very bouncy indeed.. I originally got it from a bloke who
fitted it to his sports car, but found it totally unusable due to the bounce
in the needle making measurements totally useless.
Stupid design.
Brian


You can make meter movements that are critically damped
or overdamped, for instrumentation.

All that making an underdamped meter does, is avoid
paying license fees to some patent holder.

https://image.slidesharecdn.com/nec4...?cb=1522695081

"Pointer and coil tend to oscillate
before settling. Damping force is
provided by eddy current in the
aluminium coil former."

This means there is a design method to modify
the dynamic behavior of the meter needle.

Paul

Harry Bloomfield wrote:
Dave Plowman (News) used his keyboard to write :
Another way is to get a suitable shunt with leads and crock clips etc
(perhaps build it yourself?) and use an ordinary DVM across it. You'd
obviously need to make a calibration table. Or trim the size of the
shunt.
A length of ally would what I'd try - and file the width down to
calibrate.

On a car, you can put your meter end to end across the main battery
thick cable, using that as the shunt. You can calibrate the meter using
a resistance in series with the meter.

You can calibrate using a clamp-on DC ammeter.

Those do +/- and also handle very large currents.

Paul