I dont Understand My Ampere meter

[skmdmasud]

View attachment 67883View attachment 67884

I have this ampere meter. When i connect it with LM350 and put a huge load all i see is 1.5 ampere, when i connect 2 X lm350 i get 3 amp, where else it should give 3A and 6A respectively. It shows exactly half.

Did i connected the wire correctly on the back of the meter or do i need to put some resistor or something with the meter.

Regards.

 

[picbits]

Put another ammeter in series to check its accuracy. You may find it is working properly and the problem is elsewhere.

 

[JimB]

What makes you think that the LM350 is giving 3 Amp?
Did you measure it?

Oh, yes you did, you measured it with that meter and only got 1.5 A.

I suspect that there is something wrong with your set-up.

JimB

 

[skmdmasud]

What makes you think that the LM350 is giving 3 Amp?
Did you measure it?

Oh, yes you did, you measured it with that meter and only got 1.5 A.

I suspect that there is something wrong with your set-up.

JimB

1XLM350 should give 3 amp. where else it gives only 1.5 and when i connect 2XLM350 with the same load i get 3 amp.

I think there is some configuration??

 

[skmdmasud]

Put another ammeter in series to check its accuracy. You may find it is working properly and the problem is elsewhere.

Sorry just have one... I am planning to buy a digital one...

 

[jpanhalt]

What is the voltage differential between in and out? The LM350 is internally limited at high differentials. See Figure 6 (?) of the datasheet.

John

 

[skmdmasud]

What is the voltage differential between in and out? The LM350 is internally limited at high differentials. See Figure 6 (?) of the datasheet.

John

Voltage difference is 10VDC. input is 30VDC and output is 20VDC

 

[jpanhalt]

Is it well heat sinked? A 10-volt drop at 3A = 30W, which exceeds the maximum of 25W for the device. Without good heat sinking, it should shut down even before reaching 25W.

Can you measure the voltage differential across your ammeter? If you don't have a voltmeter, are you sure the voltage differential is just 10V?

John

 

[skmdmasud]

Hi
it is in a good size heat sink.. I have voltmeter, i measure the voltage difference while its was on load but dont remember exactly...it was above 24v most probable.. That is why i said my Amp meter is spooky because when i connected LM317 i got half of 1.5 amp with the same load... i better buy a digital one, hope they are not that expensive..

 

[audioguru]

A digital multimeter is VERY inexpensive over here. The amount of pay for working half an hour for the average worker.
The same as the cost of two large pizzas or 8 bottles of beer. Almost as much cost as 9 liters of gasoline.

An LM317, LM338 and LM350 reduces its maximum output current when the voltage difference from the input to the output exceeds 10V or 15V.

EDIT: The same as the cost of one large pizza plus 4 bottles of beer, BURP.

 

[skmdmasud]

A digital multimeter is VERY inexpensive over here. The amount of pay for working half an hour for the average worker.
The same as the cost of two large pizzas or 8 bottles of beer. Almost as much cost as 9 liters of gasoline.

An LM317, LM338 and LM350 reduces its maximum output current when the voltage difference from the input to the output exceeds 10V or 15V.

EDIT: The same as the cost of one large pizza plus 4 bottles of beer, BURP.

It should be around around 10L of gasoline here as well... Is there any specific things in an amp meter to look for before buying...

 

[JimB]

two large pizzas or (and) 8 bottles of beer

Now THAT is a good idea AG!

Count me in.

JimB

 

[audioguru]

Our son took my wife and I to a basketball game. Our team won and got a score over 100. Since a sponsor of our team is PizzaPizza then every ticket gets a free slice of pizza.

We went to a new PizzaPizza store and got two free HUGE slices of the best pizza I have ever wolfed down. The pretty young lady working there asked, "Do you want the largest slices, sir?" while she rotated the huge pizza and exposed her **** to me (never mind).
And of couse I washed my pizza down with lots of beer.

Mmmm. I'll go back to that store. Guess why?

 

[picbits]

A digital multimeter is VERY inexpensive over here. The amount of pay for working half an hour for the average worker.
The same as the cost of two large pizzas or 8 bottles of beer. Almost as much cost as 9 liters of gasoline.
EDIT: The same as the cost of one large pizza plus 4 bottles of beer, BURP.

Over here, a large Dominos pizza is around £17, 9 liters of gasoline is £12.60, 12 cans of 500ml supermarket own brand beer is £6.99 or if you like a real ale £1.50 for a pint bottle.

A basic digital multimeter with a 10 amp function can be had for around £5 - sometimes they are on offer for £2.50 each.

 

[audioguru]

Over here, .....

You are badly being ripped off.

Google conversion:
1) One Canadian dollar= £0.64
2) One large Canadian pizza= £3.20
3) 9 liters of gasoline = £7.49
4) Hey, your cans of beer are larger than mine. I get a free 473ml can of beer in a case of 24 bottles of BURP. Each bottle is only 341ml and costs £0.73.
5) A cheapo digital multimeter is £6.40.
6) An average wage is £38,400 per year or £13.15 per hour.
7) Most medical care is free (government paid).
8) School is free but University is not.

 

[dr pepper]

I just passed a garage, petrol is £1.42 a litre.
A pint of beer in the pub yesterday was £3.00
Instead of a 6 pack x 330ml beer here in the uk is usually a 4 pack x 440 or 500ml, very similar difference, only in an off licence a 4 pack is around £5.00 to £6.00.
I dont like pizza, fish and chips is around £6.50
Uni and college isnt free here anymore
The average wage here amongst people I know is around £20k, and on that they are struggling, roof tax is £2k a year, electric is 15p/kwh, gas 4p/kwh and everything cost wise seems to be going silly, but I spose thats happening all over the world.
The only good thing I can say is that digital multimeters can be had for £2.00 at the electronics distibutors, and there are some in the pound shop downtown for 99p.

 

[audioguru]

I just .....

Yes, you are being ripped off. Your wages are low and your costs are high. What is your government doing?
I didn't bother looking at my electricity and natural gas prices because they are much less than yours.

 

[ChrisP58]

Setting aside discussions of world economics, and moving back to the original topic.

What is the load that you are trying to feed current to? Is it getting the current that it needs?

If it is operating properly, then that might be an indication that there is a measurement error. If it is starved, then your current source may be inadequate.

Also, remember that you can always measure current by inserting a low value resistor in series with the load, and measuring at the voltage drop across said resistor.

 

[audioguru]

Sorry for going off-topic with world economics but a current meter is EXTREMELY simple.
You are correct, it is simply a voltmeter that measures the voltage drop across a low value resistor.

 

[ericgibbs]

hi,
[MODNOTE]Please keep posts on the original topic.[/MODNOTE]