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dhe

Lesson within the lesson - Humor

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I joined a website called ohmify to help me understand electronics better. I've gotten to the point of measuring amperage in a circuit.

I managed to blow the fuse in my meter.

The lesson - you need to have a rough guess of the amperage in your circuit so you can set your (cheap) meter to the right setting so you don't blow the fuse.

 

The lesson, inside the lesson - there is a reason amp meters are of the clamp on type! 😃

 

 

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But never forget Murphy's law of transistors:

 

Any transistors in a circuit may blow to protect the fuse. 

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4 hours ago, WhataKowinkydink said:
5 hours ago, mizapf said:

I always start with 20A setting. 🙂

 

Yeah you can't got wrong setting to a higher Amperage.

AFAIK ...changing the setting, wont effect the amount of current(I) flowing through a DMM. Besides, doing so would defeat the purpose.

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The typical situation is when people new to electricity connect the Ammeter like a it is a voltmeter, across the load.

This causes all the current that the power source can deliver to flow through the ammeter. 

It's hard in the beginning, to remember to put the ammeter in series with the load.

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My meter:

image.thumb.png.be580bb13fdfd7bc12fdf104e9a76502.png

 

It does have up to 10 Amps setting, you have to change the side the probe is plugged in to, and milliamps and microamps (probe plugged in to side shown in photo).

So Mizapf suggestion makes perfect sense.

There are to ceramic fuses.

A 10A, 250V that protects the 10A connector and A 250 mA at 250V on the other side.

I have a box of fuses on their way.

 

Oddly, have had meters since I was 15, never tried to read amps before because I didn't understand the concepts. I believe I'm not alone, I went to your tube and there are lots of meter unboxing with a demo of reading voltage and continuity, but about 90% never discuss checking amperage.

 

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4 hours ago, dhe said:

My meter:

image.thumb.png.be580bb13fdfd7bc12fdf104e9a76502.png

 

It does have up to 10 Amps setting, you have to change the side the probe is plugged in to, and milliamps and microamps (probe plugged in to side shown in photo).

So Mizapf suggestion makes perfect sense.

There are to ceramic fuses.

A 10A, 250V that protects the 10A connector and A 250 mA at 250V on the other side.

I have a box of fuses on their way.

 

Oddly, have had meters since I was 15, never tried to read amps before because I didn't understand the concepts. I believe I'm not alone, I went to your tube and there are lots of meter unboxing with a demo of reading voltage and continuity, but about 90% never discuss checking amperage.

 

 

BigClive is always a good source of information.

"How to use your trashy meter without blowing it up (much)"

 

 

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18 hours ago, dhe said:

I managed to blow the fuse in my meter.

 

18 hours ago, dhe said:

The lesson - you need to have a rough guess of the amperage in your circuit so you can set your (cheap) meter to the right setting so you don't blow the fuse.

 

18 hours ago, mizapf said:

I always start with 20A setting. 🙂

 

 

4 hours ago, dhe said:

My meter:

image.thumb.png.be580bb13fdfd7bc12fdf104e9a76502.png

 

It does have up to 10 Amps setting, you have to change the side the probe is plugged in to, and milliamps and microamps (probe plugged in to side shown in photo).

So Mizapf suggestion makes perfect sense.

There are to ceramic fuses.

A 10A, 250V that protects the 10A connector and A 250 mA at 250V on the other side.

I have a box of fuses on their way.

 

Oddly, have had meters since I was 15, never tried to read amps before because I didn't understand the concepts. I believe I'm not alone, I went to your tube and there are lots of meter unboxing with a demo of reading voltage and continuity, but about 90% never discuss checking amperage.

 

I must say, I have never seen a meter configured this way before(two fuses, shared V/I on same probe)! That would make a difference...:grin: didn't mean to step on any toes.:roll:

 

While moving the HOT probe between the meter's ports may be somewhat of a selection change, perhaps more importantly it changes the MAXIMUM RATINGS, and should in best practice be necessarily required in order to change the probes resistance.:twisted:

 

One important thing for Test Techs, is the ability to differentiate between electrical parameters, ratings, ranges, and device options. An auto-ranging meter might tend to defeat this goal somewhat. As it moves the decimal point for you.:ponder:

 

The ability to take current and voltage measurements from the same probe connector means the operator can create a short circuit just by turning the dial! This puts an additional measure of critical responsibility on the user.:?

 

Not to be overlooked, is that the use of a HIGH-Z, voltage-only, probe connection, would not only protect the circuits being tested, but could also save the tech from being electrocuted!:o Maybe that's why my school used the CIRCUITMATE DM-10.|:)

 

           chrysler-corp-gold-tool-award_1_1c731a987dbdbf5c614ed6489feac5b8.thumb.jpg.9ddb243a2bd7f28f1e0d4e8bd6fb31b2.jpg

 

  ...This one's been rebranded.

Edited by HOME AUTOMATION
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15 hours ago, dhe said:

Oddly, have had meters since I was 15, never tried to read amps before because I didn't understand the concepts. I believe I'm not alone, I went to your tube and there are lots of meter unboxing with a demo of reading voltage and continuity, but about 90% never discuss checking amperage.

That's because, as mentioned above, it's harder to check current. Voltage - just tap any two points and read. Continuity - check two points again, hopefully after remembering to turn off the power. But current - you need to insert the meter into the circuit - current must pass THROUGH it. That usually means disconnecting wires (or even cutting them!) and somehow attaching the meter so that whatever you are measuring can run.

 

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Thanks for the link on how-to a multimeter...  I've been able to use mine successfully over these years w/o blowing it out...  I just move knobs around until I find something that looks as expected.  Now, hopefully, I'll know...  I want to ohmify, too!

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I started formally in basic electronics and electricity in 1984, upon going in the US Navy.  Here is a good reference to get you going, they really start you with the basic fundamentals

 

https://maritime.org/doc/neets/mod01.pdf

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