How do you read a Sperry ohms meter?

[ba_50]

Hi,

I have a Sperry SP-152A needle tester (multi-meter) and the instruction manual was worthless.

It has 3 dial positions 1, Rx10, and 1K. I assume 1 is the lowest setting.

Does anyone want to try and explain how it works? My knowlege on electronics is about ziltch.

Is there a book I could get on the subject of multimeters? The library couldn't get me one.

If I wanted to test for something in the 500 ohm range would it be on the 1 setting?

Thanks.

 

[Boatist]

Re: How do you read a Sperry ohms meter?

To read Something near 500 Ohms that you know has no voltage on it.

First must have a good battery in the meter.

Black lead goes to the common plug.

Red Lead goes to the V/Ohms/A.

Put the switch in the Ohms times 10 postion.

Touch your Red and Black leads together.

Turn the knob to adjust the meter to 0 (zero).

Zero Ohms is the top scale with the meter needle all the way to the right over the 0.

Put one lead on each side of the device you want to read.

On the times 10 scale 500 Ohms will read 50.

If the circuit has VOLTAGE on it do not try and read with meter set to OHMS.

 

[JB]

Re: How do you read a Sperry ohms meter?

First, ba 50, you need to understand two things about resistance reading on an analog multimeter:

1. Full deflection of the needle is zero resistance, zero deflection is infinity (open circuit).

2. The scale for resistance is nonlinear, so we use different ranges to try to get mid-scale deflection while reading the resistance we expect.

Get those things clear, then follow the excellent instructions Boatist has offered.

Good luck.

 

[ba_50]

Re: How do you read a Sperry ohms meter?

Thanks a lot. My reading checked out with the boat mechanics. A friend of mine read it wrong possibly due to a light stroke. I hope that isn't the problem. He was a mechanic too.

 

[ba_50]

Re: How do you read a Sperry ohms meter?

I tried to measure the coils this morning and realized I'm still not sure how to read the 1 and 1K settings? They talk about low and high settings. I assume 1 is the lowest setting and 1K is the highest. Can you explain those for me? Thanks again.

 

[JB]

Re: How do you read a Sperry ohms meter?

The Ohmmeter part of your multimeter has a battery, ba 50.

The different ranges for resistance reading apply different amounts of voltage to the resistance you are testing. To get half, or mid-scale deflection on the meter, typically requires .5 milli-amp.

In the X1 scale the meter would apply a very small voltage. In the X1K range the applied voltage would be 1000 times more, to get the same deflection with 1000 times as much resistance.

In the X1 scale you would read the resistance off of the meter scale as printed, in the X1K scale you multiply the reading by 1000 (1K) to get the resistance the meter is measuring.

 

[ba_50]

Re: How do you read a Sperry ohms meter?

JB,

You have been a great help. Thanks again. Bob

 

[Saskatoon2005]

Re: How do you read a Sperry ohms meter?

I even learned something from you JB, you are a great source of help to many people on here. I used to get those Radio Shack electronic kits for birthdays and Christmas' so I learned alot about electronic parts, and am able to understand lots on the subject, but it has been a while since dealing with it. Reading your postings above kinda turned on a light in my head and I nodded to myself and was like," Hey yeah, I remember that!" So thanks JB for turning on the light...LOL! d