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Measure Your Magnetism!
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deleted-338773
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Measure Your Magnetism!
My multimeter isn't showing any thing! Why?
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deleted-249560
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Re: Measure Your Magnetism!
Bummer. When you say it doesn't show anything, what does that mean? The display is completely blank? It always shows 0.00? It always shows something else?
You can check that the meter is working by turning it on, putting the red led in the socket marked for 'volts', 'DCV' or some other indication. The manual that came with the meter will tell you how your specific one work. Put the black lead in the black socket which is probably marked as 'COM', 'Common' or 'GND'. Set the meter to the 20V range if it has manual range setting. Touch the red lead of the meter to one connector on the 9V battery and the other lead to the other connector. The meter should read either 9.00 or -9.00, depending on which lead you put where.
With the circuit built, but the black lead of the meter in with one of the black connections in the diagram. Any will do - the long row of holes with the blue line next to it is fine. Touch the red lead to the leftmost pin of the voltage regulator. You should see 9.00V (more or less). Move that red lead to the rightmost pin and you should see 5.00V (more of less). Then with no magnets nearby, the rightmost pin (orange wire in the photo) should show you 2.50V (more or less). If you see all of that than you've wired it correctly.
Can you describe what you see (or don't see)?
Howard
You can check that the meter is working by turning it on, putting the red led in the socket marked for 'volts', 'DCV' or some other indication. The manual that came with the meter will tell you how your specific one work. Put the black lead in the black socket which is probably marked as 'COM', 'Common' or 'GND'. Set the meter to the 20V range if it has manual range setting. Touch the red lead of the meter to one connector on the 9V battery and the other lead to the other connector. The meter should read either 9.00 or -9.00, depending on which lead you put where.
With the circuit built, but the black lead of the meter in with one of the black connections in the diagram. Any will do - the long row of holes with the blue line next to it is fine. Touch the red lead to the leftmost pin of the voltage regulator. You should see 9.00V (more or less). Move that red lead to the rightmost pin and you should see 5.00V (more of less). Then with no magnets nearby, the rightmost pin (orange wire in the photo) should show you 2.50V (more or less). If you see all of that than you've wired it correctly.
Can you describe what you see (or don't see)?
Howard
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deleted-338773
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Re: Measure Your Magnetism!
It Only shows 0.00 and a battery sign and I've calibrated it to 20v max
Last edited by deleted-338773 on Wed Jan 27, 2016 7:34 am, edited 1 time in total.
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deleted-338773
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Re: Measure Your Magnetism!
hpw do I add an image
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deleted-338773
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Re: Measure Your Magnetism!
Whenever I insert the Hall Effect Sensor, it briefly displays numbers under 1 then it disappears to 0.00
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deleted-249560
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Re: Measure Your Magnetism!
Seeing your setup would help. To post an image you have to upload it to a server somewhere, then in your message here, click on the 'Img' button above. You'll see [ img ][/ img ] appear (without the extra spaces in it) and you simply put the URL of your image in between the ']' and '['.
Check that if your meter has two places for a red lead that you have it one that says 'V' and not one that says 'A'. Please post a shot of your setup and maybe we can get you going.
Oh sorry - you can put pictures on just about any free image posting service like http://postimage.org or http://s5.photobucket.com .
Howard
Check that if your meter has two places for a red lead that you have it one that says 'V' and not one that says 'A'. Please post a shot of your setup and maybe we can get you going.
Oh sorry - you can put pictures on just about any free image posting service like http://postimage.org or http://s5.photobucket.com .
Howard
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deleted-338773
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deleted-338773
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Re: Measure Your Magnetism!
A better one!
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deleted-249560
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Re: Measure Your Magnetism!
I was hoping that the second better image was viewable, but it's not. There was something wrong with the way you posted it. From what I can see in the first one, your meter is a DT-830B? If it is, then it looks like you have the leads plugged into the right place. I don't see any obvious wiring mistakes but it's a very fuzzy picture.
On Monday I suggested that you use the meter to measure the battery voltage, then the regulator output, and finally the output of the magnetic sensor. Can you try that and let's make sure your meter is working?
If you can try resending the second better photo, please do.
Howard
On Monday I suggested that you use the meter to measure the battery voltage, then the regulator output, and finally the output of the magnetic sensor. Can you try that and let's make sure your meter is working?
If you can try resending the second better photo, please do.
Howard
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deleted-338773
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Re: Measure Your Magnetism!
I don't get it. My multimeter is working fine, I checked it with the steps you provided. All it displays it 7.3 V when I put my meter to a max of 20DCV. Whenever I touch a rare-earth magnet to it, it stays at 7.3. What do I do.
Better Image:
http://postimg.org/image/mthokxswl/
Better Image:
http://postimg.org/image/mthokxswl/
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deleted-249560
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Re: Measure Your Magnetism!
That image is a lot more readable. Thanks.
In general, black or green wires are assumed to be negative or ground when possible, and red or white is considered positive. When you connected your meter, you put the 9V battery into the breadboard just fine but then connected the black lead of the meter through a red test lead and the red lead of the meter to your board with a black test lead. It's very confusing and makes it hard to tell for sure what you're doing.
What is apparent though is that the voltage regulator, the larger of the two chips doesn't have a connection to the negative side, or ground. The middle pin needs to be connected to the blue (negative or minus) power bus. Also the middle pin of the magnetic sensor needs to be connected to the negative side or ground as well.
It's always good to double check your wiring. It looks like you left out two critical wires.
To make the next picture less confusing - please switch out the red and black test leads so that you have a red lead clipped to the red meter probe and a black clip connected to the black meter probe. Put the other black clip end to the green wire coming from the blue bus as you had it.
Then:
1) Using the red clip at the other end of the lead clipped to the red meter probe, touch the positive connection to the battery. You should see 9V.
2) Touch the leftmost pin of the regulator chip. You have it connected properly to the red bus on your breadboard. It too should show 9V.
3) Touch the rightmost pin of the regulator which is also the leftmost pin of the magnetic sensor. It should read 5 volts.
4) Touch the rightmost pin of the magnetic sensor which is shown in your picture with a green wire. Either the pin or the wire is fine - it should read 2.5V.
5) Assuming you got this far, move a magnet near the sensor and the voltage should change.
I'm a little concerned that you're seeing 7.5V on the output of the sensor since it's not designed to run at voltages over 5 volts. It's possible that with your changing things you damaged one or both of the chips - or *hopefully* the problem is simply the two wires you left out.
Howard
In general, black or green wires are assumed to be negative or ground when possible, and red or white is considered positive. When you connected your meter, you put the 9V battery into the breadboard just fine but then connected the black lead of the meter through a red test lead and the red lead of the meter to your board with a black test lead. It's very confusing and makes it hard to tell for sure what you're doing.
What is apparent though is that the voltage regulator, the larger of the two chips doesn't have a connection to the negative side, or ground. The middle pin needs to be connected to the blue (negative or minus) power bus. Also the middle pin of the magnetic sensor needs to be connected to the negative side or ground as well.
It's always good to double check your wiring. It looks like you left out two critical wires.
To make the next picture less confusing - please switch out the red and black test leads so that you have a red lead clipped to the red meter probe and a black clip connected to the black meter probe. Put the other black clip end to the green wire coming from the blue bus as you had it.
Then:
1) Using the red clip at the other end of the lead clipped to the red meter probe, touch the positive connection to the battery. You should see 9V.
2) Touch the leftmost pin of the regulator chip. You have it connected properly to the red bus on your breadboard. It too should show 9V.
3) Touch the rightmost pin of the regulator which is also the leftmost pin of the magnetic sensor. It should read 5 volts.
4) Touch the rightmost pin of the magnetic sensor which is shown in your picture with a green wire. Either the pin or the wire is fine - it should read 2.5V.
5) Assuming you got this far, move a magnet near the sensor and the voltage should change.
I'm a little concerned that you're seeing 7.5V on the output of the sensor since it's not designed to run at voltages over 5 volts. It's possible that with your changing things you damaged one or both of the chips - or *hopefully* the problem is simply the two wires you left out.
Howard
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deleted-338773
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Re: Measure Your Magnetism!
I already tried grounding it, still nothing different. The multimeter is working fine.
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deleted-249560
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Re: Measure Your Magnetism!
If I knew the results of the tests I suggested, I could help you further. Without knowing what voltages appeared when you tested them there's not much else to suggest.
You put the two missing wires in place - that's a critical step. Can you shoot another picture showing as much detail of the wiring as possible?
Looking at the chips so that you can see the markings on them, when you put the black lead of the meter to ground (battery negative) and the red lead to the leftmost pin of the voltage regulator (bigger of the two chips), what voltage did you see?
When you touch the lead to the center pin of the voltage regulator, what voltage did you see?
When you touch the lead to the rightmost pin of the voltage regulator, what voltage did you see?
When you touch the lead to the leftmost pin of the magnetic sensor, what voltage did you see?
When you touch the lead to the center pin of the magnetic sensor, what voltage did you see?
When you touch the lead to the rightmost pin of the magnetic sensor, what voltage did you see?
Please shoot a new picture of the wiring after you fixed it and post your answers to the questions. Otherwise I don't have any other suggestions for you. With that information I might be able to tell you if you have a problem with one of the chips or something.
Howard
You put the two missing wires in place - that's a critical step. Can you shoot another picture showing as much detail of the wiring as possible?
Looking at the chips so that you can see the markings on them, when you put the black lead of the meter to ground (battery negative) and the red lead to the leftmost pin of the voltage regulator (bigger of the two chips), what voltage did you see?
When you touch the lead to the center pin of the voltage regulator, what voltage did you see?
When you touch the lead to the rightmost pin of the voltage regulator, what voltage did you see?
When you touch the lead to the leftmost pin of the magnetic sensor, what voltage did you see?
When you touch the lead to the center pin of the magnetic sensor, what voltage did you see?
When you touch the lead to the rightmost pin of the magnetic sensor, what voltage did you see?
Please shoot a new picture of the wiring after you fixed it and post your answers to the questions. Otherwise I don't have any other suggestions for you. With that information I might be able to tell you if you have a problem with one of the chips or something.
Howard
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deleted-338773
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Re: Measure Your Magnetism!
I get 0.00 volts for all of them except for when I touch the leads to the 9V battery, in which I get 2.5 volts (my multimeter is calibrated at 20 VDC-
deleted-338773
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Re: Measure Your Magnetism!
Here's two pictures. I have to hand in the project this Friday. Oh, I just remembered. My equipment isn't from Jameco as indicated in the idea.
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deleted-249560
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Re: Measure Your Magnetism!
Thanks for the updated pictures and checking things. A top-down view of the board would help if you could do that.
If you touched the multimeter leads directly to the battery and got 2.5 volts, that's bad. If the multimeter were working correctly it would display something near 9 volts. Whether you got the stuff from Jameco or not doesn't matter. Inexpensive meters sometimes do have problems and a broken one isn't very useful.
Looking at your wiring though, let's imagine you were looking at the magnetic sensor (smaller chip) from the front where you could read the markings on it. From what i can tell it's plugged into rows 36, 37 and 38. You have a small orange wire going into row 36 from row 33 which *should* be the 5 volts from the voltage regulator. Row 37 has a small red wire going to your negative or ground, and row 38 is the output from the sensor. The meter appears to be plugged into that row and if things were working, the meter should be showing 2.5 volts. It's clearly not.
If you did go through each pin as I suggested and saw 0 volts on all of them except for touching the battery itself and seeing 2.5 volts, you either have a dead battery or a broken meter. Can you measure something else? Do you have a AA or some other sort of cylindrical battery you can measure? Leave the meter set for 20V and try that. You should see something like 1.5 volts on a new battery. Put two of them end to end, pointing the same way with the button of one touching the flat side of the other. Put the red meter lead on the button and the black on the flat side - you should see 3 volts.
If you do see 1.5 volts with one and 3 volts with two, you have a dead 9 volt battery. If you see 0 or something really low on the other batteries, you have a broken meter. Try that and write back please.
Howard
If you touched the multimeter leads directly to the battery and got 2.5 volts, that's bad. If the multimeter were working correctly it would display something near 9 volts. Whether you got the stuff from Jameco or not doesn't matter. Inexpensive meters sometimes do have problems and a broken one isn't very useful.
Looking at your wiring though, let's imagine you were looking at the magnetic sensor (smaller chip) from the front where you could read the markings on it. From what i can tell it's plugged into rows 36, 37 and 38. You have a small orange wire going into row 36 from row 33 which *should* be the 5 volts from the voltage regulator. Row 37 has a small red wire going to your negative or ground, and row 38 is the output from the sensor. The meter appears to be plugged into that row and if things were working, the meter should be showing 2.5 volts. It's clearly not.
If you did go through each pin as I suggested and saw 0 volts on all of them except for touching the battery itself and seeing 2.5 volts, you either have a dead battery or a broken meter. Can you measure something else? Do you have a AA or some other sort of cylindrical battery you can measure? Leave the meter set for 20V and try that. You should see something like 1.5 volts on a new battery. Put two of them end to end, pointing the same way with the button of one touching the flat side of the other. Put the red meter lead on the button and the black on the flat side - you should see 3 volts.
If you do see 1.5 volts with one and 3 volts with two, you have a dead 9 volt battery. If you see 0 or something really low on the other batteries, you have a broken meter. Try that and write back please.
Howard