amperage requirements?

[the_doc735]

18 hours ago, Superdad said:

 

Not really, but I will partially. With an ammeter you break the wire and insert the ammeter into the circuit.  If you have only a voltmeter then measure the drop and calculate.  Here is a easy Youtube example:

 

I still do not understand why you don't just pick a 5-7 amp LPS and be happy.  What's your budget?

 

.....

1) I don't really want to explain the voltage drop method. If you have only a voltmeter then measure the drop and calculate, (see video).

2) With an ammeter you break the wire and insert the ammeter into the circuit in series.

3) I still do not understand why you don't just pick a 5-7 amp LPS and be happy.  

4) What's your budget?

**********************************************************************************************************

1) Thanks for the vid. link.
2) Yes, I know.
3) Because one of my options was Paul Hynes and he requested these readings so that he could make a bespoke/custom LPSU, tailor made for it's purpose. This is because he is a perfectionist! - I am still considering the "off the shelf"/"off the peg" alternatives though.
4) Enough for a paul hynes. The rest would have to be cheaper though, month by month.
5) you and others say that a DMM is the preferred way to measure, but why is a DMM preferred over a clamp meter please? (anyone?)

 

Cheers!

[the_doc735]

These are accurate measurements, disregard previous measurements!

 

 

[Superdad]

11 minutes ago, the_doc735 said:

These are accurate measurements, disregard previous measurements!

 

Well those look more like it.  Now you are getting somewhere.  That's a mighty power hungry machine you are running though.

[the_doc735]

48 minutes ago, Superdad said:

 

Well those look more like it.  Now you are getting somewhere.  That's a mighty power hungry machine you are running though.

Meter settings:

5. CURRENT (DCA)

*Use Centre Socket!

 

*0 to 200 uA (not on all models!)
*0 to 2000 uA
*0 to 20 mA
0 to 200 mA

'10'?

 

I used the 20mA, hope that was correct? It didn't overload or 'blow'.

 

[Superdad]

59 minutes ago, the_doc735 said:

I used the 20mA, hope that was correct? It didn't overload or 'blow'.

 

Uh, then your readings were milliAmps and not Amps!  So I don't think you measured right.

And yes, there is a good chance that you overloaded your meter.  Why would you use the 20mA setting for measuring current draw in the thousands of mA?!

[the_doc735]

5 minutes ago, Superdad said:

 

Uh, then your readings were milliAmps and not Amps!  So I don't think you measured right.

And yes, there is a good chance that you overloaded your meter.  Why would you use the 20mA setting for measuring current draw in the thousands of mA?!

@Superdad  

no it didn't overload because the readout tells you if it is overloaded, and there was no indication of any overload i.e. no malfunctions, no blown fuses etc. 

Please look at the picture above of the DMM. You will see there are only 4 ranges available: 

0 to 2000 uA
0 to 20 mA
0 to 200 mA

'10'?

....so. is the only one suitable the 10? assuming that means amps?   ...but it says on the DMM 10sec max, every 15 minutes! I don't think 10 seconds is long enough to get accurate readings when you are waiting for a boot up, and then a time period to settle to an idle state?

It seems these ranges are common to most DMM? Are there any others that read actual AMPS for a decent length of time?

Many thanks!

[Superdad]

57 minutes ago, the_doc735 said:

Are there any others that read actual AMPS for a decent length of time?

 

Absolutely!  Of course you have to spend more than $30 for one. 

[rickca]

From the instructions for Gunson PocketMeter 2 

 

For this reason, Pocketmeter includes a fuse which limits the current to 500 mA. (Inadvertent connection to a higher current source, while the switch is set to milliamps, will immediately blow this fuse). The 0 -10 Amp range is unprotected by a fuse, so care must be taken to avoid damage.

[mansr]

Just get a basic Fluke. Or a high-end model. Either one costs but a small fraction of an audiophile USB cable.

[the_doc735]

2 hours ago, rickca said:

From the instructions for Gunson PocketMeter 2 

 

For this reason, Pocketmeter includes a fuse which limits the current to 500 mA. (Inadvertent connection to a higher current source, while the switch is set to milliamps, will immediately blow this fuse). The 0 -10 Amp range is unprotected by a fuse, so care must be taken to avoid damage.

your point being?

[the_doc735]

3 hours ago, Superdad said:

 

Absolutely!  Of course you have to spend more than $30 for one. 

so, what are they please?

[the_doc735]

2 hours ago, mansr said:

Just get a basic Fluke. Or a high-end model. Either one costs but a small fraction of an audiophile USB cable.

examples please? Even some flukes have those common ranges!

[the_doc735]

3 hours ago, rickca said:

From the instructions for Gunson PocketMeter 2 

 

For this reason, Pocketmeter includes a fuse which limits the current to 500 mA. (Inadvertent connection to a higher current source, while the switch is set to milliamps, will immediately blow this fuse). The 0 -10 Amp range is unprotected by a fuse, so care must be taken to avoid damage.

your point being?

@Superdad stated, "you overload your meter! i.e. blow the fuse."

@rickca stated, "Pocketmeter includes a fuse which limits the current to 500 mA."

@Superdad stated, "measuring current draw in the thousands of mA."

 

My interpretation of this is: superdad thinks I should be measuring 1000-6000mA (=1-6 amps total for each of the 3 amperages). This means that if the fuse blows at 500mA(?), the fuse would have blown every time I tried to measure! ~ BUT IT DIDN'T!! i.e. the load would have been far too much! ~ BUT IT WASN'T!! - I agree with superdad! - setting the meter to 20mA should blow the fuse when subjecting the meter to 1000-6000mA, with a fuse that only withstands 500mA ~ BUT IT DIDN'T!!

 

So, what is going on here? ...does anyone know for sure?

[jabbr]

 

Does anybody really know how many amps there are? ...

[the_doc735]

@Superdad 

...as the rated 500mA fuse did not blow on any of the 11 lines (i.e 3.3 [x4], 5 [x5], 12 [x2] V) with a setting of 20mA; that tells us that each of the 11 lines are all below 500mA rating each!

 

That gives us:

3.3v - 2000mA MAX. (2A)

5.0v - 2500mA MAX. (2.5A)

12.0v - 1000mA MAX. (1A)

 

...do you concur please?

[the_doc735]

3 minutes ago, jabbr said:

 

Does anybody really know how many amps there are? ...

not really helpful.

[rickca]

1 hour ago, the_doc735 said:

your point being?

I was trying to be helpful, but I'll put you back on ignore now.

[the_doc735]

1 hour ago, rickca said:

I was trying to be helpful, but I'll put you back on ignore now.

why?

[the_doc735]

got a chance to borrow this:

 

SIMPLE INSTRUCTIONS:

Turn off power to the circuit.   Discharge all high-voltage capacitors.

Insert the red test lead into the mAµA or A terminal and  black  test  lead  into  the  COM terminal.

If you are using the A terminal, set the rotary switch to A.   If you are using mAµA terminal, set the rotary switch to µA for currents below 40000µA

(UT71A is 20000µA), or for current above mA 40000µA (UT71B is 20000µA).

DC measurement is default, press blue button to select AC measurement.

Open the circuit path to be tested.  Touch the red testing leads to the more positive side of the break; touch the black probe to the more negative side of the  bread. Reversing  the  leads will produce  a negative reading, but will not damage the Meter.

Turn on power to the circuit; then read the display. AC measurement displays the True RMS value. DC measurement displays the effective 
value of sine wave (mean value response).

Turn off power to the circuit and discharge all high- voltage capacitors.  Remove the Meter and restore.

 

Anyone got any tips about setting this up for measuring the 24 pin ATX input on the mobo?

Cheers!

[the_doc735]

NOTE: (UT71B) 

 

Autoranging (AUTO lighted in the display) always comes on initially when you select a new function. In autorange, the Meter selects the lowest input range possible, ensuring that the reading appears with the highest available resolution.

[the_doc735]

@Superdad  @rickca  @mansr @jabbr

 

OK – finally borrowed the ut71B DMM.

Connected black to comm.

Connected red to 10A.

Switched dial to DCA (not mA/uA/nA).

Auto ranging engages by default!!

Inserted probes in series.

For now: I have just measured one 12v rail cable ONLY.

I booted the PC and observed the reading for the PEAK boot ‘rush’:

….this was   00.014A !

As with the first measurements when I admitted I forgot the diagram was upside down; the fact still remains that with both DMM & clamp meters, the given reading still stubbornly remains at just a few milliamps! I have tried five meters and they all give milliamp readings! Even when the various cables are ‘summed’ together as a total.

What do you make of this please?

Do you have any advice regarding how I should connect & configure the UT71B DMM?

Cheers!

[the_doc735]

34 minutes ago, the_doc735 said:

@Superdad  @rickca  @mansr @jabbr

 

OK – finally borrowed the ut71B DMM.

Connected black to comm.

Connected red to 10A.

Switched dial to DCA (not mA/uA/nA).

Auto ranging engages by default!!

Inserted probes in series.

I did not engage the peak function.

For now: I have just measured one 12v rail cable ONLY.

I booted the PC and observed the reading for the PEAK boot ‘rush’:

….this was   00.014A !

As with the first measurements when I admitted I forgot the diagram was upside down; the fact still remains that with both DMM & clamp meters, the given reading still stubbornly remains at just a few milliamps! I have tried five meters and they all give milliamp readings! Even when the various cables are ‘summed’ together as a total.

What do you make of this please?

Do you have any advice regarding how I should connect & configure the UT71B DMM?

Cheers!

@Shadders @gstew

[the_doc735]

@RickyV   ...how is this off topic please? I am trying to discover the amperage for my mobo, using a DMM is all part of that process, unless someone already knows the answer because they have done it themselves on a previous occasion!

[jabbr]

1) measure each rail/voltage

2) multiply by a factor that reflects the inaccuracy in your measurements 

3) estimate the peak power based on the devices on your mobo — CPU , GPU & PCIe cards.

 

Ensure that your measurements fall reasonably close to the estimates, safest to use the higher of the two

 

Each mobo & CPU, GPU and PCIe combo will have different numbers. A 400W ATX supply will always be safe except if you have a power hungry situation. A 200W ATX supply will often be safe in a reasonably low power situation. 

[the_doc735]

23 hours ago, jabbr said:

1) measure each rail/voltage

2) multiply by a factor that reflects the inaccuracy in your measurements 

3) estimate the peak power based on the devices on your mobo — CPU , GPU & PCIe cards.

 

Ensure that your measurements fall reasonably close to the estimates, safest to use the higher of the two

 

Each mobo & CPU, GPU and PCIe combo will have different numbers. A 400W ATX supply will always be safe except if you have a power hungry situation. A 200W ATX supply will often be safe in a reasonably low power situation. 

just to check I got this right:

the quoted measurement 00.014A (inaccuracy (0.7%+30/according to UNI-T) = 00.0182A     .....is this right please?

 

Obviously I still need to measure all the 3.3/5/12v cables and sum (+) each group like superdad said?

cheers!