Please explain my meter to me.

[ieezitin]

Could someone please explain all the functions of my multy meter and what it can and or cannot do. and how to use it.
Below is the picture of my meter so you can reference from there.

Many Thanks     Anthony.

[tinkerer]

You can download the manual from http://www.retrevo.com/search/v2/jsp/mytrevo/myTrevo.jsp?page=man.
That will get you started. Then take a course in AC/DC theory and that will get you a little further. Just kidding, the manual should help a lot.

[sorveltaja]

Anthony, if you start of the green coloured ohm-scale, on the left side is diode tester/ continuity tester. Rest of the green scale is to choose, what resistor values you need to measure.

Next thing in the clockwise is the black scale. It is a DC voltage scale. With that, you can measure things like 1.5V or 9V batteries, that have + and - poles.
When measuring, at first, always set the meter to its highest voltage value.

Red scale is for an AC voltage. Similar to what is used on tv's and other home devices.

Next are ACA, and DCA scales. Both measure currents. Never put the probes straight to the current source, as it might damage the multimeter. Serial resistance is most probably required for that operation.

What's left is the hFE-portion. With that, you can measure transistor values, when they are inserted to that blue socket.

Hope this helps .

[Bernd]

Too add further to sorveltaja's fine explaination.

On the Ohm scale the left most symbol is a diode. Use this to check if a diode is either open or working. You should hear a sound. If not reverse the leads. If you still don't have a sound then the diode is open (like a filiment on a blown bulb) or if it makes a sound if it's connected either way it's no good. Checking must be done with the diode out of the circuit board.

On the amp scale you need to move the black lead to the black hole marked 2 A Max when checking for a current under 2 amps and all the way to the left if your current is going to be more than 2 amps, but less than 10 amps.

Got more questions, just ask.

Bernd

[John Rudd]

What's left is the hFE-portion. With that, you can measure transistor values, when they are inserted to that blue socket.

hFE is the current gain of a transistor...its a function of collector current/ base current...

Unless you are into electronics... ( if you are you would know) Don't worry about it


If you wanna know we can discuss that later..

[ieezitin]

Gentlemen.

I thank you all for your posts, Tinkerer the manual for the meter helps a lot thank you for the link.

Ok. Sorveltaja / Bernd I read both and let me see if I have this correct. I think I know what a diode is, I believe its function is to let current pass only one way a little bit like a check valve in a piping system, a resistor is a piece that when you lets say put 12 volt 2 amp current to one end out the other comes 9 volt 1 amp right? And the drop in voltage and amps is the resistance I think.  So on the green scale of the meter the values are shown of what the particular resistor is resisting, and the one set on the scale that has the black arrow with a line through it and the music sign is the test of the diode ( open or closed).
Question here. In the diode tester position, is it true that if I had lets say had a cable with 3 wires in it and they are all the same color and I wanted to know what wire is what, and if I connect one probe to one end of one wire and try all the other ends with the other probe and it bleeps,  the one that bleeps is the one wire that is connected to the other probe? And does this mean continuity, is this what that means?

The DCV / ACV I know, example if I put the two probes into the wall socket set the dial on  200 ACV the meter reads 125 that’s telling me that there is 125 volts ac which is what we use here in the US.

Now on the DCA / ACA I am really lost. You both say do not go to source current to find your amperage values well how do you do it.

HFE ok I give up.

Thank you all again. I am learning a lot.    Anthony.

[Bluechip]

Anthony

Why not just Google something like 'Using a Multimeter' ?

http://www.doctronics.co.uk/meter.htm#digital

This is the first one ( of many ) I got.

Before you destroy yourself/meter/circuit  .... not joking ...

Seen it, done it, survived it. Some don't.  120VAC/240VAC bites. And bites hard. You need to know what you're doing, and why you are doing it.
Otherwise some thing will let go. Usually the meter, but not always ..

Dave BC 

[tinkerer]

You check continuity in the ohms position with no power applied. You can check continuity with power applied in the volts position, but there must be a voltage drop across the points you are testing.

[Bernd]

Anthony,

Think of a diode as a one way valve. The hydraulic anlogy would be that the valve will only let the fluid, in this case electricity, flow one way but not the other. One use of a diode is to rectify AC to, what is known as half wave, DC. Four diodes wired together a certain way will give you a rectifier. This will give you full DC voltage. A full bridge rectifier is used in a circuit in a DC power supply. If I remember correctly a diode will drop .7 volt.

Yes, you can used the diode position to find the correct wire out of the three.

Individual components should all be check "out of circuit" if possible. Reason being there might be another path connected with the component that you want to check.

When using resistors in circuits you also need to consider the wattage of the resistor. Common wattges are 1/8W, 1/4w, 1/2W, 1W and so on up. I don't know how high they go.

Yes, the green scale will tell you the resistance. Try it out by checking a couple of resistors. I've uploaded a convenient resistor chart. Copy it and print it out.



When checking any value of voltage or current always set the meter to the highest setting if the voltage is unknow to you. Lets say you want to check the voltage of a transformer that is a step up transformer, in other words you put in 120volts and it doubles it to 240volts. Set the meter to at least the next higher setting. In your meter's case it would be 700volts since the 200 setting would not be high enough.

When checking amperage the meter actually needs to be put "into" the line. In other words you need to connect the meter with the current flowing through the meter. This is best learned by working with a 12 volt power supply.

Let me see if I can find a diagram or draw one up on how this is done.

Bernd

[75Plus]

Continuing Bernd's hydraulic analogy. a resistor is similar to a restrictor plate or orifice and a capacitor works like an accumulator.

One more item that should be addressed is amps supplied to a circuit. No matter what the power supply can supply in amps the load will draw only the current, (amperage), to operate the circuit. In the case of a motor, with no load applied, the current drawn will be low. As the load increases the current will increase also. If you have a fixed load, such as a 12 volt, 12 watt, light bulb the current flow will be 1 amp with 12 volts applied. There is no way to send more current into the bulb if the voltage remains constant.

Joe

[Bernd]

Thanks for adding that Joe. I'd completley forgotten about the rest of the hydraulic anlogy.

Bernd

[ieezitin]

Gentlemen.

Thank you for helping me understand.

Bluechip, thank you.  I did google and try to get some idea and it only worked so far, experience from people who know is ten times better, plus I had questions that needed to be answered. every time I got explanations when I researched it they were written as if I knew the basics of components. 

Tinkerer, Bernd. Great explanations which made sense to me I now have a better basic understanding of what I am dealing with and I will experiment with parts from old trash electronics I have laying around and I will be safe.

One more time thank you all.      Anthony.

[Bernd]

Just thought of the other hydraulic anology. Voltage = Volume and Current = Pressure.   

If I'm wrong I'm sure somebody will let me know. 

Bernd

[kvom]

Just thought of the other hydraulic anology. Voltage = Volume and Current = Pressure.

I think it's the opposite.

[spuddevans]

Here's another analogy, imagine a road with cars on it travelling at a speed. The road is the wire, the amount of cars = Currant and the speed of the cars = voltage.

A single lane road could allow a lesser amount of cars on it at some very high speeds, but a 6-lane highway will allow many many more cars to travel at both low and high speeds. In electronics, a reletively thin wire can carry some very high voltages (high speed cars) but only at lower currants (amount of cars), whereas a thicker cable will carry much heavier currants at both lower and higher voltages.

This is why the cables in your car are thicker than those in your home electrics, the car works on a reletively low voltage (12-14 volts) compared to the house that (in the uk) runs on 230Volt (or 110 volts in the US). So to power the same 100 watts, the car cable will have to handle around 8.3 Amps compared to the house cable will carry only 0.43 Amp ( in the uk, 0.9 Amp in the US ), raise the power to 1000 Watts and the cable size differences get even more obvious.


Tim

[tinkerer]

Here is a great explaination of Ohm's Law.
http://www.the12volt.com/ohm/ohmslaw.asp

[Bernd]

Just thought of the other hydraulic anology. Voltage = Volume and Current = Pressure.

I think it's the opposite.

Your right Kirk it's Voltage = Pressure and Current = Volume.

I knew I'd get straightened out if I was wrong. 

Bernd

[ieezitin]

Tim

Well put. Through that descriptive explanation all the parts like diodes, resisters and others make sense. Diodes are one way streets, resisters are two lane road merging into one lane, transformers are like you driving on one lane then filtering onto a 6 lane high way.
Now I think its relatively easy the only thing I need to find out now is the reasons for using all these parts and why. And I am sure that’s a whole other story in its self.

Anthony.