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I also have a couple of questions on the "meter movement" on page 27.
Where is it in the kit list? What is the part called?
Where can I buy one?
Cheers -
I also have a couple of questions on the "meter movement" on page 27.
Where is it in the kit list? What is the part called?
Where can I buy one?
Cheers
Am having the exact same issue. Its rather frustrating - I just spent a few hundred pounds on parts following the list, set up a lab .. its taken quite some time to get to this point. Very first lab in the book and he's talking about a part that's not in the list. Doesn't help that rather than being a "guided" lab where he tells you what to do, its a "figure it out on your own" deal.
Essentially its a "D'Arsonval movement" that we need, which is the mechanism inside an analog voltmeter. I am wondering if you can just buy a cheap voltmeter and pull its guts out.
I am also wondering how many more of these little "no parts" landmines are scattered throughout the book. He acknowledges in places that things will be different for home users, then promptly forgets it in the next paragraph.
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Maybe not every lab is worth doing. If you don't have an analog meter (even a V-O-M), skip over it and come back some day. Or not...
The more interesting lab is a few pages later where the topic is diode I-V curves.
If you want a nice analog meter, here is the replacement part for the venerable Simpson 260
http://www.ebay.com/itm/Simpson-260-Series-6XLP-replacement-front-meter-panel-for-VOM-multimeter-/262927460493
Or the entire meter:
http://www.ebay.com/itm/Simpson-260-series-7-analog-VOM-protected-Volt-Ohm-Milliameter-/112374043361
Everybody needs a V-O-M and the Simpson 260 has been around for decades.
I was always partial to Triplett
http://www.ebay.com/itm/Lot-2-Triplett-630-VOM-Portable-Desktop-Volt-Ohm-Milliammeter-Multimeter-Module-/112361841372
Availability varies by country, of course, but there should be something available locally.
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Hi rstofer
The thing is its not the entire meter you need, just the mechanical movement. I would like to complete it, but moving on til I can source one is certainly a thought worth entertaining, and now I have a new problem .... I have been searching through my bags and bags of parts from digikey and mouser for 20 minutes looking for my 1N914 Diode
I need some parts stores -
You should be able to find a meter on ebay, just search for analog panel meter. Does the book give any kind of specification? Current required for full scale reading might be all that's important.
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Hi rstofer
The thing is its not the entire meter you need, just the mechanical movement. I would like to complete it, but moving on til I can source one is certainly a thought worth entertaining, and now I have a new problem .... I have been searching through my bags and bags of parts from digikey and mouser for 20 minutes looking for my 1N914 Diode
I need some parts stores
Use a 1N4148
https://electronics.stackexchange.com/questions/166828/difference-between-1n914-and-1n4148-diodes
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You will run across obsolete component requirements throughout the book. The book is OLD!
So, hit up Google and see what shakes out. "replacement for 1N914" is one way to find a substitute.
I like the old 1N914 and I have a hundred or so. They are still available but the 1N4148 is easier to source.
Part of the learning experience will be substituting obsolete components and the other will be in scaling the problems. You might not have a particular resistor or capacitor value. Coming up with a substitute and intuiting how the results will change turns out to be more important than the original experiment.
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I don't think doing the hands with the analog ammeter and voltmeter(pgs 27-28) is that critical. It is clearly discussing it as a classroom exercise set up by an instructor.
But if you want to experiment with analog panel ammeters, they're very cheap on eBay.
As far as diodes used with this, the current version of this book (2016) suggests 1N4004 s which are easy to source.
The 1N914 seen in the drawing of the circuit on the following page (29) - used to draw diode IV curves -could be substituted with almost any common diode, including a 1N4004. -
You will run across obsolete component requirements throughout the book. The book is OLD!
So, hit up Google and see what shakes out. "replacement for 1N914" is one way to find a substitute.
I like the old 1N914 and I have a hundred or so. They are still available but the 1N4148 is easier to source.
Part of the learning experience will be substituting obsolete components and the other will be in scaling the problems. You might not have a particular resistor or capacitor value. Coming up with a substitute and intuiting how the results will change turns out to be more important than the original experiment.
I am using the brand new version of the student manual that was recently released (not the old spiral bound silver thing), and have got a 1N914 in the suggested kit. Good to know that finding ways round the problem will still be of use though! -
You will run across obsolete component requirements throughout the book. The book is OLD!
So, hit up Google and see what shakes out. "replacement for 1N914" is one way to find a substitute.
I like the old 1N914 and I have a hundred or so. They are still available but the 1N4148 is easier to source.
Part of the learning experience will be substituting obsolete components and the other will be in scaling the problems. You might not have a particular resistor or capacitor value. Coming up with a substitute and intuiting how the results will change turns out to be more important than the original experiment.
I am using the brand new version of the student manual that was recently released (not the old spiral bound silver thing), and have got a 1N914 in the suggested kit. Good to know that finding ways round the problem will still be of use though!
I have the latest version as well but the book itself is still OLD. Whatever updates that may have been made certainly haven't drug it into the 21st century. In some ways, this is a good thing. The book is still using DIP components instead of moving on to SMD and adapters.
There are going to be a lot of issues with obsolete components and working around that fact is part of the exercise. From a hobbyist point of view, that may be the more important lesson. There are a lot of projects on the Internet that are old enough that component availability is an issue. It's good to know how to work around that fact.
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Re: "Meter Movement"
It appears that the objective here is to learn how to design a circuit that allows one to measure Voltage, Current, and Resistance over several ranges with nothing but a power source and a few resistors and a simple meter. The exercise teaches how a VOM multi-meter (whether digital or analog) works. And it gives you the understanding how to measure and scale various electrical properties.
For example, if you were making a bench power supply, you would understand the principles of using a shunt to measure current. Doesn't matter whether you are displaying the current on a vintage D'Arsonval panel meter, or feeding an Analog to Digital converter input.
When the book says "bare meter movement" it means a simple analog panel meter. It does not mean the very fragile and delicate D'Arsonval motor mechanism INSIDE the case. Unless you intend to become an "electronic archaeologist" and repair the antique things it is sufficient to understand that the meter needle moves relative to the amount of current through the coil.
If I were doing this experiment, I would get something like: 50UA DC PANEL METER - CAT# PMD-50UA
$12.00 each" http://www.allelectronics.com/item/pmd-50ua/50ua-dc-panel-meter/1.html
Using a meter that already has all the Volt, Amp, Ohms scales printed on it (as that Ebay Simpson replacement) is "cheating" as it has already worked out the non-linear resistance scale, etc. The objective of the exercise appears to be working out the circuit configuration, resistance/shunt values, and creating your own scales, especially for resistance.
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Re: "Meter Movement"
It appears that the objective here is to learn how to design a circuit that allows one to measure Voltage, Current, and Resistance over several ranges with nothing but a power source and a few resistors and a simple meter. The exercise teaches how a VOM multi-meter (whether digital or analog) works. And it gives you the understanding how to measure and scale various electrical properties.
For example, if you were making a bench power supply, you would understand the principles of using a shunt to measure current. Doesn't matter whether you are displaying the current on a vintage D'Arsonval panel meter, or feeding an Analog to Digital converter input.
When the book says "bare meter movement" it means a simple analog panel meter. It does not mean the very fragile and delicate D'Arsonval motor mechanism INSIDE the case. Unless you intend to become an "electronic archaeologist" and repair the antique things it is sufficient to understand that the meter needle moves relative to the amount of current through the coil.
If I were doing this experiment, I would get something like: 50UA DC PANEL METER - CAT# PMD-50UA
$12.00 each" http://www.allelectronics.com/item/pmd-50ua/50ua-dc-panel-meter/1.html
Using a meter that already has all the Volt, Amp, Ohms scales printed on it (as that Ebay Simpson replacement) is "cheating" as it has already worked out the non-linear resistance scale, etc. The objective of the exercise appears to be working out the circuit configuration, resistance/shunt values, and creating your own scales, especially for resistance.
Hi Richard
I think that is what I will ultimately end up doing. Will a panel meter contain any resistors? As you say the aim is to first make a voltmeter, and then an ammeter from the same equipment. I am assuming that any pre-installed resistors would make the exercise more difficult?
EDIT: And yes you are correct, the aim of the experiment is simply to first design the circuit such that you get full deflection at 10V, and then the second one at 2mA. No cheating with pre-calibrated meters
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Will a panel meter contain any resistors?
That is why I selected the very lowest value (most sensitive) DC ammeter from the wide variety of mechanically identical meters offered on that page. The 50uA meter is the LEAST likely to contain ANY internal shunt, etc. And even if it did, it wouldn't change the objective and learning from the experiment.
All the other meters certainly contain shunts (for higher-current Ammeters), and/or series resistance (for Volt meters) and/or rectifiers (for AC meters). They are fundamentally all the same 50uA meter movement, but with various other internal components to allow measuring higher amps, volts, AC, etc.
And that is essentially the purpose of the experiment. To first measure the sensitivity of the basic meter movement, and then design the external circuit to allow measurement of other things based on that. -
I have the latest version as well but the book itself is still OLD. Whatever updates that may have been made certainly haven't drug it into the 21st century. In some ways, this is a good thing. The book is still using DIP components instead of moving on to SMD and adapters.
There are going to be a lot of issues with obsolete components and working around that fact is part of the exercise. From a hobbyist point of view, that may be the more important lesson. There are a lot of projects on the Internet that are old enough that component availability is an issue. It's good to know how to work around that fact.
Hm that is disappointing to hear, especially as someone looking to learn. Thanks again for your help however. -
Will a panel meter contain any resistors?
That is why I selected the very lowest value (most sensitive) DC ammeter from the wide variety of mechanically identical meters offered on that page. The 50uA meter is the LEAST likely to contain ANY internal shunt, etc. And even if it did, it wouldn't change the objective and learning from the experiment.
All the other meters certainly contain shunts (for higher-current Ammeters), and/or series resistance (for Volt meters) and/or rectifiers (for AC meters). They are fundamentally all the same 50uA meter movement, but with various other internal components to allow measuring higher amps, volts, AC, etc.
And that is essentially the purpose of the experiment. To first measure the sensitivity of the basic meter movement, and then design the external circuit to allow measurement of other things based on that.
Thank you, I will go down this path then. Much appreciate the help! -
I'm not thrilled either. On page 30, it mentions an experiment set up by the instructor. A footnote mentions that those doing it at home, and instructors, can get the instructions on the website. Are they there? Nope. (I just emailed them about this.)I have the latest version as well but the book itself is still OLD. Whatever updates that may have been made certainly haven't drug it into the 21st century. In some ways, this is a good thing. The book is still using DIP components instead of moving on to SMD and adapters.
Hm that is disappointing to hear, especially as someone looking to learn. Thanks again for your help however.
There are going to be a lot of issues with obsolete components and working around that fact is part of the exercise. From a hobbyist point of view, that may be the more important lesson. There are a lot of projects on the Internet that are old enough that component availability is an issue. It's good to know how to work around that fact. -
Thanks for all the advice and help guys!
A cheap analogue meter has been bought, looking forward to making the circuit.
Cheers,
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I'm not thrilled either. On page 30, it mentions an experiment set up by the instructor. A footnote mentions that those doing it at home, and instructors, can get the instructions on the website. Are they there? Nope. (I just emailed them about this.)
Did you get a reply at all? I also sent him one over a week ago but got nothing back. -
Nope, not a peep.I'm not thrilled either. On page 30, it mentions an experiment set up by the instructor. A footnote mentions that those doing it at home, and instructors, can get the instructions on the website. Are they there? Nope. (I just emailed them about this.)
Did you get a reply at all? I also sent him one over a week ago but got nothing back.
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I'm not thrilled either. On page 30, it mentions an experiment set up by the instructor. A footnote mentions that those doing it at home, and instructors, can get the instructions on the website. Are they there? Nope. (I just emailed them about this.)
The experiment on page 30 is simply to get voltage versus current for some instructor assembled 'black boxes'. All this means is that you don't get to see inside the box and by making measurements, you deduce what has to be inside.
The instructions just aren't important and are not needed. Grab a resistor or two, maybe a diode (what they are really trying to show) and a capacitor (should probably be large if you want to see the meter move slowly and maybe a current limiting resistor 10 ufd 100k?). I would put a current limiting resistor in series with the diode as well (100 Ohms?). I don't want the diode current approaching infinity just after it starts to conduct.
You are to graph voltage versus current (the capacitor will ramp or spike, the resistor will be nice and linear and the diode won't conduct until you have about 0.7V across it in the proper direction) and try to determine what is in the box. Don't forget to check both polarities. The box could have a diode in parallel with a resistor (besides the current limiting resistor) so the measurements would vary depending on polarity. Tricky, those black boxes.
Put a 9V battery in series with a 100 Ohm resistor, seal the box and work through the Thevenin equivalent circuit. Good stuff!
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If you have a large value inductor plus a series resistor, you can pretend they are in a 'black box' as well.
You should probably have the various current limiting resistors outside the box. This way you can get at both terminals of the 'hidden' device. Otherwise, you can only measure the current because the voltage will be whatever is supplied by the power supply.
Or, build 3 terminal boxes so you can get at the junction of the resistor/device. That extra resistor in parallel with the diode is still pretty tricky.
In one direction, the device looks like a simple resistor - nice and linear current vs voltage. In the other direction, the current takes off after the voltage gets to about 0.7V.
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The point is, the book expressly says that one can get the instructions on the website, but you can't, and they're unresponsive to contact. Lame.