Where to procure meters?
magnet18, Thu May 12 2011, 02:46AMHey all, I need to get 3 AC voltmeters, 0-15 volts, 3 AC voltmeters, 1-110V, 3 AC ammeters, 0-5A, 3 DC voltmeters, 0-15 volts, and 3 DC ammeters, 0-5A.
And I would like to get these without going broke.
And I want them to match visually by type, not ALL of them(unless it's cheap), I just want the AC voltmeters to match, and the DC voltmeters to match, and etcetera.
Does anybody have any clue as to how to get these cheap? The cheapest I can find online is $15 a piece, so new is obviously not the way to go, since I need 15. That is $125. Not happening.
Thoughts?
Re: Where to procure meters?
Patrick, Thu May 12 2011, 03:25AM
Do you mean the meter movements, like analog ones?
Patrick, Thu May 12 2011, 03:25AM
Do you mean the meter movements, like analog ones?
Re: Where to procure meters?
Steve Conner, Thu May 12 2011, 09:40AM
Best advice I can give is to keep an eye on Ebay, try surplus stores and so on. Matching sets of analog meters are tricky to find.
Steve Conner, Thu May 12 2011, 09:40AM
Best advice I can give is to keep an eye on Ebay, try surplus stores and so on. Matching sets of analog meters are tricky to find.
Re: Where to procure meters?
Proud Mary, Thu May 12 2011, 10:09AM
Wouldn't a switching scheme of some sort enable you to use fewer meters?
As for finding matching moving coil panel meters of good quality, I'd suggest looking for ebay sellers in eastern Europe - Latvia, Lithuania, Bulgaria, Romania - where large stocks of technical inventory were abandoned after the collapse of the Soviet empire.
Even so, once freight charges have been added, you must not expect to get your 15 meter movements for pennies.
Economics has always been central to engineering design, so you must first decide your budget for this project, and then work out how your goals can be achieved within these financial limits.
Proud Mary, Thu May 12 2011, 10:09AM
Wouldn't a switching scheme of some sort enable you to use fewer meters?
As for finding matching moving coil panel meters of good quality, I'd suggest looking for ebay sellers in eastern Europe - Latvia, Lithuania, Bulgaria, Romania - where large stocks of technical inventory were abandoned after the collapse of the Soviet empire.
Even so, once freight charges have been added, you must not expect to get your 15 meter movements for pennies.
Economics has always been central to engineering design, so you must first decide your budget for this project, and then work out how your goals can be achieved within these financial limits.
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 11:41AM
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
Start winding some coils, get a pack of 30 identical magnets, and see what happens (use a DMM to calibrate them)
(I stripped a moving coil meter down once, there isn't that much involved)
I appreciate that you need 5 different types of meter, but this can be achieved using resistors and diodes (I think). It could be quite a worthwhile little project.
EDIT: If digital meters will be suitable, there are chips available, and circuits online. 15 LCD's or whatever shouldn't cost too much.
Ash Small, Thu May 12 2011, 11:41AM
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
Start winding some coils, get a pack of 30 identical magnets, and see what happens (use a DMM to calibrate them)
(I stripped a moving coil meter down once, there isn't that much involved)
I appreciate that you need 5 different types of meter, but this can be achieved using resistors and diodes (I think). It could be quite a worthwhile little project.
EDIT: If digital meters will be suitable, there are chips available, and circuits online. 15 LCD's or whatever shouldn't cost too much.
Re: Where to procure meters?
Patrick, Thu May 12 2011, 02:07PM
Patrick, Thu May 12 2011, 02:07PM
Ash Small wrote ...
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
Start winding some coils, get a pack of 30 identical magnets, and see what happens (use a DMM to calibrate them)
(I stripped a moving coil meter down once, there isn't that much involved)
I appreciate that you need 5 different types of meter, but this can be achieved using resistors and diodes (I think). It could be quite a worthwhile little project.
EDIT: If digital meters will be suitable, there are chips available, and circuits online. 15 LCD's or whatever shouldn't cost too much.
Yeah but their pretty precise engineered devices. I dont know about building them, id go with LED or LCD's then theyll be the same and cheap.If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
Start winding some coils, get a pack of 30 identical magnets, and see what happens (use a DMM to calibrate them)
(I stripped a moving coil meter down once, there isn't that much involved)
I appreciate that you need 5 different types of meter, but this can be achieved using resistors and diodes (I think). It could be quite a worthwhile little project.
EDIT: If digital meters will be suitable, there are chips available, and circuits online. 15 LCD's or whatever shouldn't cost too much.
Re: Where to procure meters?
Proud Mary, Thu May 12 2011, 02:08PM
What, the cost of a light engineering factory once you've finished your apprenticeship as an instrument maker?
Proud Mary, Thu May 12 2011, 02:08PM
Ash Small wrote ...
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
What, the cost of a light engineering factory once you've finished your apprenticeship as an instrument maker?
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 05:32PM
A pillar drill should be sufficient. Magnet 18 says he has one in this thread:
and that he has access to other tools.
A moving coil meter only has one moving part, the coil, usually pivoting on a pin. (I believe some have a return spring, similar to a watch spring, but other types of spring should work, with a suitable tension adjuster (nut and bolt, for example). Some, I believe just use gravity)
You basically 'tune' it by altering the number of turns on the coil, altering spring tension, or by 'biasing' with resistors (if that is the correct terminology.)
As Patrick points out, solid-state may be simpler, depending on personal preferance and ability, but once you devise a suitable pivot mechanism (pin, sharpened at both ends, between two centre-popped plates, separated by nuts, bolts and washers) the rest is just basic electro-magnetic theory and epoxy, etc.
It would cost pennies (or cents, depending on location)
Print off the graduated faces on a printer using a CAD or graphics package, and cannibalise some old CD cases for the windows.
Care obviously needs to be taken when positioning the magnets and epoxying them in, but final calibration can be done by altering number of windings, spring tension and biasing resistors if required.
Hardly complicated!
Rolling your own means YOU have TOTAL CONTROL over quality, accuracy, etc, limited only by what you use to calibrate it against.
( a better approach may be to mark off the graduations by hand, while comparing with a DMM or whatever)
Ash Small, Thu May 12 2011, 05:32PM
Proud Mary wrote ...
What, the cost of a light engineering factory once you've finished your apprenticeship as an instrument maker?
Ash Small wrote ...
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
What, the cost of a light engineering factory once you've finished your apprenticeship as an instrument maker?
A pillar drill should be sufficient. Magnet 18 says he has one in this thread:
and that he has access to other tools.
A moving coil meter only has one moving part, the coil, usually pivoting on a pin. (I believe some have a return spring, similar to a watch spring, but other types of spring should work, with a suitable tension adjuster (nut and bolt, for example). Some, I believe just use gravity)
You basically 'tune' it by altering the number of turns on the coil, altering spring tension, or by 'biasing' with resistors (if that is the correct terminology.)
As Patrick points out, solid-state may be simpler, depending on personal preferance and ability, but once you devise a suitable pivot mechanism (pin, sharpened at both ends, between two centre-popped plates, separated by nuts, bolts and washers) the rest is just basic electro-magnetic theory and epoxy, etc.
It would cost pennies (or cents, depending on location)
Print off the graduated faces on a printer using a CAD or graphics package, and cannibalise some old CD cases for the windows.
Care obviously needs to be taken when positioning the magnets and epoxying them in, but final calibration can be done by altering number of windings, spring tension and biasing resistors if required.
Hardly complicated!
Rolling your own means YOU have TOTAL CONTROL over quality, accuracy, etc, limited only by what you use to calibrate it against.
( a better approach may be to mark off the graduations by hand, while comparing with a DMM or whatever)
Re: Where to procure meters?
Proud Mary, Thu May 12 2011, 06:04PM
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
Proud Mary, Thu May 12 2011, 06:04PM
Ash Small wrote ...
A pillar drill should be sufficient. Magnet 18 says he has one in this thread:
and that he has access to other tools.
A moving coil meter only has one moving part, the coil, usually pivoting on a pin. (I believe some have a return spring, similar to a watch spring, but other types of spring should work, with a suitable tension adjuster (nut and bolt, for example). Some, I believe just use gravity)
You basically 'tune' it by altering the number of turns on the coil, altering spring tension, or by 'biasing' with resistors (if that is the correct terminology.)
As Patrick points out, solid-state may be simpler, depending on personal preferance and ability, but once you devise a suitable pivot mechanism (pin, sharpened at both ends, between two centre-popped plates, separated by nuts, bolts and washers) the rest is just basic electro-magnetic theory and epoxy, etc.
It would cost pennies (or cents, depending on location)
Print off the graduated faces on a printer using a CAD or graphics package, and cannibalise some old CD cases for the windows.
Care obviously needs to be taken when positioning the magnets and epoxying them in, but final calibration can be done by altering number of windings, spring tension and biasing resistors if required.
Hardly complicated!
Rolling your own means YOU have TOTAL CONTROL over quality, accuracy, etc, limited only by what you use to calibrate it against.
( a better approach may be to mark off the graduations by hand, while comparing with a DMM or whatever)
Proud Mary wrote ...
What, the cost of a light engineering factory once you've finished your apprenticeship as an instrument maker?
Ash Small wrote ...
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
If I needed 15 identical meters I'd look into what was involved in making them.
The setup costs will be the same for one as for 15.
What, the cost of a light engineering factory once you've finished your apprenticeship as an instrument maker?
A pillar drill should be sufficient. Magnet 18 says he has one in this thread:
and that he has access to other tools.
A moving coil meter only has one moving part, the coil, usually pivoting on a pin. (I believe some have a return spring, similar to a watch spring, but other types of spring should work, with a suitable tension adjuster (nut and bolt, for example). Some, I believe just use gravity)
You basically 'tune' it by altering the number of turns on the coil, altering spring tension, or by 'biasing' with resistors (if that is the correct terminology.)
As Patrick points out, solid-state may be simpler, depending on personal preferance and ability, but once you devise a suitable pivot mechanism (pin, sharpened at both ends, between two centre-popped plates, separated by nuts, bolts and washers) the rest is just basic electro-magnetic theory and epoxy, etc.
It would cost pennies (or cents, depending on location)
Print off the graduated faces on a printer using a CAD or graphics package, and cannibalise some old CD cases for the windows.
Care obviously needs to be taken when positioning the magnets and epoxying them in, but final calibration can be done by altering number of windings, spring tension and biasing resistors if required.
Hardly complicated!
Rolling your own means YOU have TOTAL CONTROL over quality, accuracy, etc, limited only by what you use to calibrate it against.
( a better approach may be to mark off the graduations by hand, while comparing with a DMM or whatever)
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 06:22PM
It's around 35 years since I stripped one down and repaired it (when I was 12 or 13), but I remember it was very simple.
If I was Magnet18, I'd get one, even a non-working one, strip it down, and have a look at what's involved.
Maybe the simplest way to settle this 'debate' would be for me to make one and post details in the 'projects' thread?
Ash Small, Thu May 12 2011, 06:22PM
Proud Mary wrote ...
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
It's around 35 years since I stripped one down and repaired it (when I was 12 or 13), but I remember it was very simple.
If I was Magnet18, I'd get one, even a non-working one, strip it down, and have a look at what's involved.
Maybe the simplest way to settle this 'debate' would be for me to make one and post details in the 'projects' thread?
Re: Where to procure meters?
Proud Mary, Thu May 12 2011, 06:36PM
You clearly have skills a whole order of magnitude greater than my own very modest capabilities, and it was wrong of me to judge you by the standards of ordinary men.
Proud Mary, Thu May 12 2011, 06:36PM
Ash Small wrote ...
It's around 35 years since I stripped one down and repaired it (when I was 12 or 13), but I remember it was very simple.
If I was Magnet18, I'd get one, even a non-working one, strip it down, and have a look at what's involved.
Maybe the simplest way to settle this 'debate' would be for me to make one and post details in the 'projects' thread?
Proud Mary wrote ...
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
It's around 35 years since I stripped one down and repaired it (when I was 12 or 13), but I remember it was very simple.
If I was Magnet18, I'd get one, even a non-working one, strip it down, and have a look at what's involved.
Maybe the simplest way to settle this 'debate' would be for me to make one and post details in the 'projects' thread?
You clearly have skills a whole order of magnitude greater than my own very modest capabilities, and it was wrong of me to judge you by the standards of ordinary men.
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 06:56PM
Flattery will get you nowhere, PM.
But seriously, the hardest part I can see is being able to operate a centre-punch correctly.
I generally use a CAD package to print out a template, then sellotape it to the metal stock. It's hardly 'rocket science', but it does involve a modicum of 'skill and dexterity', which generally comes with practice (or is it perseverance?).
Ash Small, Thu May 12 2011, 06:56PM
Flattery will get you nowhere, PM.
But seriously, the hardest part I can see is being able to operate a centre-punch correctly.
I generally use a CAD package to print out a template, then sellotape it to the metal stock. It's hardly 'rocket science', but it does involve a modicum of 'skill and dexterity', which generally comes with practice (or is it perseverance?).
Re: Where to procure meters?
magnet18, Thu May 12 2011, 07:47PM
I think winding some galvos might be the best option if I can pull it off, though I think I'll go with the stationary coil/ iron needle design.
magnet18, Thu May 12 2011, 07:47PM
Proud Mary wrote ...
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
I can make a clock out of 40xx chips, does that count?If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
I think winding some galvos might be the best option if I can pull it off, though I think I'll go with the stationary coil/ iron needle design.
Re: Where to procure meters?
Patrick, Thu May 12 2011, 08:03PM
Patrick, Thu May 12 2011, 08:03PM
magnet18 wrote ...
I think winding some galvos might be the best option if I can pull it off, though I think I'll go with the stationary coil/ iron needle design.
If you can do any of this -- ill be impressed, im not so foolish to even attempt it.Proud Mary wrote ...
If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
I can make a clock out of 40xx chips, does that count?If you have the skill, know how, and facilities to make, for example only, a pocket watch out of metal stock, you might very well be able to make an accurate moving coil meter, but who can say?
I think winding some galvos might be the best option if I can pull it off, though I think I'll go with the stationary coil/ iron needle design.
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 08:23PM
Thinking about it, I think the one I pulled apart all those years ago may have been a stationary coil design. Not sure, but I may have been mislead by the fact that they are generally referred to as 'moving coil meters'. (It was a long time ago....)
I think it's certainly worth considering, especially if you want 15 of them, and don't want to pay much for them.
And calibrating them yourself means they will be as accurate as you choose to make them. (ie, they should be a lot more accurate than 'cheap' ones from Ebay). Plus, they will all be identical.
Just my 2 cent's worth.
Ash Small, Thu May 12 2011, 08:23PM
magnet18 wrote ...
I think winding some galvos might be the best option if I can pull it off, though I think I'll go with the stationary coil/ iron needle design.
I think winding some galvos might be the best option if I can pull it off, though I think I'll go with the stationary coil/ iron needle design.
Thinking about it, I think the one I pulled apart all those years ago may have been a stationary coil design. Not sure, but I may have been mislead by the fact that they are generally referred to as 'moving coil meters'. (It was a long time ago....)
I think it's certainly worth considering, especially if you want 15 of them, and don't want to pay much for them.
And calibrating them yourself means they will be as accurate as you choose to make them. (ie, they should be a lot more accurate than 'cheap' ones from Ebay). Plus, they will all be identical.
Just my 2 cent's worth.
Re: Where to procure meters?
Proud Mary, Thu May 12 2011, 08:40PM
Designing and manufacturing those spiral springs so they provide a linear and proportional reaction across the whole scale looks a ticklish business, even for those who breezed through the selection of ferromagnetic alloys, machining, tapping, annealing, degaussing, and all the rest.
Proud Mary, Thu May 12 2011, 08:40PM
Designing and manufacturing those spiral springs so they provide a linear and proportional reaction across the whole scale looks a ticklish business, even for those who breezed through the selection of ferromagnetic alloys, machining, tapping, annealing, degaussing, and all the rest.
Re: Where to procure meters?
magnet18, Thu May 12 2011, 08:42PM
I'm thinking this doesn't look too bad
Wrap the coil around a pencil, careful cutting of tin-plated steel for the needle, the hardest part I see is a low-friction pivot...
magnet18, Thu May 12 2011, 08:42PM
I'm thinking this doesn't look too bad
Wrap the coil around a pencil, careful cutting of tin-plated steel for the needle, the hardest part I see is a low-friction pivot...
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 09:09PM
I did describe a simple low-friction pivot above.
I also agree that this would be the hardest part, but I think I've provided enough info.
If you require more info I'll be happy to elaborate.
EDIT: I seem to remember the one I rebuilt had what looked like a 'bow tie' on the bottom of the needle.
Ash Small, Thu May 12 2011, 09:09PM
I did describe a simple low-friction pivot above.
I also agree that this would be the hardest part, but I think I've provided enough info.
If you require more info I'll be happy to elaborate.
EDIT: I seem to remember the one I rebuilt had what looked like a 'bow tie' on the bottom of the needle.
Re: Where to procure meters?
magnet18, Thu May 12 2011, 09:15PM
It would appear that you did... I'll give it a go.
As for the spring, how bout this, mount the whole thing sideways and throw the spring out altogether? Gravity is still good for a couple things I guess...
(for what it's worth I have access to lathes, band saws, drill presses, mills, plasma cutters... ect.
Friends are good, especially when they're directors of large corporations.)
magnet18, Thu May 12 2011, 09:15PM
It would appear that you did... I'll give it a go.
As for the spring, how bout this, mount the whole thing sideways and throw the spring out altogether? Gravity is still good for a couple things I guess...
(for what it's worth I have access to lathes, band saws, drill presses, mills, plasma cutters... ect.
Friends are good, especially when they're directors of large corporations.
)Re: Where to procure meters?
Ash Small, Thu May 12 2011, 09:33PM
Try it, but planar springs (watch springs) aren't that difficult to wind, especially if you incorporate a tensioner mechanism. (they usually have a 'zero' adjustment) You just have to utilize the same method for all of them for conformity.
I doubt you'll need access to the other equipment, but it may come in useful for batch production once you've developed the prototype.
I'd still reccomend getting hold of one and taking it to bits, even if it doesn't work. Maybe your school has a defective one? (that's how I got my first one)
EDIT: Maybe this thread, or the majority of it, should be moved from 'sale and trade' to another forum?
Ash Small, Thu May 12 2011, 09:33PM
Try it, but planar springs (watch springs) aren't that difficult to wind, especially if you incorporate a tensioner mechanism. (they usually have a 'zero' adjustment) You just have to utilize the same method for all of them for conformity.
I doubt you'll need access to the other equipment, but it may come in useful for batch production once you've developed the prototype.
I'd still reccomend getting hold of one and taking it to bits, even if it doesn't work. Maybe your school has a defective one? (that's how I got my first one)
EDIT: Maybe this thread, or the majority of it, should be moved from 'sale and trade' to another forum?
Re: Where to procure meters?
Patrick, Thu May 12 2011, 10:16PM
youll wnat to look up "jewel" thingies that the professionally made instrument use,which give ultra low friction. I have no idea if theis is wise or possible.
Patrick, Thu May 12 2011, 10:16PM
youll wnat to look up "jewel" thingies that the professionally made instrument use,which give ultra low friction. I have no idea if theis is wise or possible.
Re: Where to procure meters?
Ash Small, Thu May 12 2011, 11:01PM
I'd argue that the cheaper 'professionally made' instruments don't use 'jewel' technology.
Magnet18 started this thread by emphasising that the limiting factor was his budget.
A self-lubricating phosphor-bronze may have adsvantages, but what I've suggested above won't have much friction anyway.
Minimizing friction while remaining 'within budget' is the priority though, I agree.
Ash Small, Thu May 12 2011, 11:01PM
Patrick wrote ...
youll wnat to look up "jewel" thingies that the professionally made instrument use,which give ultra low friction. I have no idea if theis is wise or possible.
youll wnat to look up "jewel" thingies that the professionally made instrument use,which give ultra low friction. I have no idea if theis is wise or possible.
I'd argue that the cheaper 'professionally made' instruments don't use 'jewel' technology.
Magnet18 started this thread by emphasising that the limiting factor was his budget.
A self-lubricating phosphor-bronze may have adsvantages, but what I've suggested above won't have much friction anyway.
Minimizing friction while remaining 'within budget' is the priority though, I agree.
Re: Where to procure meters?
Sulaiman, Thu May 12 2011, 11:35PM
One cheap option may be to buy 15 low cost analogue multimeters and
use the moving coil meter part and make new scales.
(saw off the body/switch/pcb part leaving coil/magnet/housing and clear plastic front)
Sulaiman, Thu May 12 2011, 11:35PM
One cheap option may be to buy 15 low cost analogue multimeters and
use the moving coil meter part and make new scales.
(saw off the body/switch/pcb part leaving coil/magnet/housing and clear plastic front)
Re: Where to procure meters?
magnet18, Fri May 13 2011, 12:11AM
If I did that why not just use the multimeters...
Do they sell multimeters for less than $5?
magnet18, Fri May 13 2011, 12:11AM
If I did that why not just use the multimeters...
Do they sell multimeters for less than $5?
Re: Where to procure meters?
Patrick, Fri May 13 2011, 12:17AM
I just dont see how you can possibly make your own meter movements and have them be usefully accurate. honestly I would just buy some of the Harris/ intersil ICL7107CPL 40 pin IC's and then use LED 7 segment displays.
there is an example of just such a case here on the forum.
Patrick, Fri May 13 2011, 12:17AM
I just dont see how you can possibly make your own meter movements and have them be usefully accurate. honestly I would just buy some of the Harris/ intersil ICL7107CPL 40 pin IC's and then use LED 7 segment displays.
there is an example of just such a case here on the forum.
Re: Where to procure meters?
Jrz126, Fri May 13 2011, 01:09AM
I've seen them on sale for as low as 2.99 before, but that might be an in store only deal.
Jrz126, Fri May 13 2011, 01:09AM
I've seen them on sale for as low as 2.99 before, but that might be an in store only deal.
Re: Where to procure meters?
Proud Mary, Fri May 13 2011, 01:24AM
The UK price including delivery is £2.17, about US$ 3.50. It's not easy to see how a multimeter could be much cheaper.
Proud Mary, Fri May 13 2011, 01:24AM
The UK price including delivery is £2.17, about US$ 3.50. It's not easy to see how a multimeter could be much cheaper.
Re: Where to procure meters?
magnet18, Fri May 13 2011, 01:51AM
I don't understand why a multimeter is cheaper than a dedicated meter...
I'm going to check harbor freight this weekend, see what I can find.
magnet18, Fri May 13 2011, 01:51AM
I don't understand why a multimeter is cheaper than a dedicated meter...
I'm going to check harbor freight this weekend, see what I can find.
Re: Where to procure meters?
Proud Mary, Fri May 13 2011, 08:01AM
Mass production, vertical integration, low labour costs, and mass marketing on a global scale.
Proud Mary, Fri May 13 2011, 08:01AM
magnet18 wrote ...
I don't understand why a multimeter is cheaper than a dedicated meter...
I don't understand why a multimeter is cheaper than a dedicated meter...
Mass production, vertical integration, low labour costs, and mass marketing on a global scale.
Re: Where to procure meters?
Ash Small, Fri May 13 2011, 09:59AM
The physics dictates that it is simply a question of friction on one side, and power consumed on the other.
The less friction, the less power consumed for the same accuracy.
A hard steel pin, sharpened at both ends, and pivoting between two centre-punched indentations on correctly spaced (adjusted) plates would have virtually no friction anyway. The vast majority of power consumed would be in overcoming spring tension (or gravity, depending on method used).
I really don't see the problem in building an accurate analogue meter, although a digital meter would presumably draw less power from the circuit being measured, at the expense of needing it's own supply.
However, depending on Magnet18's application, if cheap DMM's with an accuracy of 2% are going to be suitable, then use those.
It basically comes down to 'what is most suitable for the application', and Magnet18 has not disclosed details of this. He simply requested advice on analogue meters.
Ash Small, Fri May 13 2011, 09:59AM
Patrick wrote ...
I just dont see how you can possibly make your own meter movements and have them be usefully accurate.
I just dont see how you can possibly make your own meter movements and have them be usefully accurate.
The physics dictates that it is simply a question of friction on one side, and power consumed on the other.
The less friction, the less power consumed for the same accuracy.
A hard steel pin, sharpened at both ends, and pivoting between two centre-punched indentations on correctly spaced (adjusted) plates would have virtually no friction anyway. The vast majority of power consumed would be in overcoming spring tension (or gravity, depending on method used).
I really don't see the problem in building an accurate analogue meter, although a digital meter would presumably draw less power from the circuit being measured, at the expense of needing it's own supply.
However, depending on Magnet18's application, if cheap DMM's with an accuracy of 2% are going to be suitable, then use those.
It basically comes down to 'what is most suitable for the application', and Magnet18 has not disclosed details of this. He simply requested advice on analogue meters.
Re: Where to procure meters?
Steve Conner, Fri May 13 2011, 11:23AM
I think taut band suspension is the simplest.
I fully agree with the other comments in this thread though. Making a meter might look very simple, but the devil is in the details. It is a difficult precision engineering job to make an accurate one. Ash, do feel free to try it and write us a project thread, it would be very interesting.
Multimeters are cheaper than panel meters just because there's a large market for them. Anyone who does DIY, car electrics, and so on, will want a basic multimeter for his toolbox. I have seen people buy a half dozen of the cheap digital ones and zip-tie them to a board to make an instrument panel.
Steve Conner, Fri May 13 2011, 11:23AM
I think taut band suspension is the simplest.
I fully agree with the other comments in this thread though. Making a meter might look very simple, but the devil is in the details. It is a difficult precision engineering job to make an accurate one. Ash, do feel free to try it and write us a project thread, it would be very interesting.
Multimeters are cheaper than panel meters just because there's a large market for them. Anyone who does DIY, car electrics, and so on, will want a basic multimeter for his toolbox. I have seen people buy a half dozen of the cheap digital ones and zip-tie them to a board to make an instrument panel.
Re: Where to procure meters?
Ash Small, Fri May 13 2011, 11:57AM
It looks like I'll have to knock something up now, just to prove a point
Your idea of 'taught band suspension' sounds pretty simple, but may suffer from rubber degradation over time (depending on materials used.)
Once I locate my stock of supermagnets (samples from the factory just off the M1 at Barlborough Links, near Chesterfield) I'll knock up a test-rig.
Ash Small, Fri May 13 2011, 11:57AM
Steve McConner wrote ...
I think taut band suspension is the simplest.
I fully agree with the other comments in this thread though. Making a meter might look very simple, but the devil is in the details. It is a difficult precision engineering job to make an accurate one. Ash, do feel free to try it and write us a project thread, it would be very interesting.
I think taut band suspension is the simplest.
I fully agree with the other comments in this thread though. Making a meter might look very simple, but the devil is in the details. It is a difficult precision engineering job to make an accurate one. Ash, do feel free to try it and write us a project thread, it would be very interesting.
It looks like I'll have to knock something up now, just to prove a point
Your idea of 'taught band suspension' sounds pretty simple, but may suffer from rubber degradation over time (depending on materials used.)
Once I locate my stock of supermagnets (samples from the factory just off the M1 at Barlborough Links, near Chesterfield) I'll knock up a test-rig.
Re: Where to procure meters?
Steve Conner, Fri May 13 2011, 12:25PM
The band is usually made of metal, not rubber. It isn't my idea, it is an industry standard design invented by Crompton or some such company.
The simplest meter movement is the cheap and nasty moving-magnet one found in car battery chargers, that would be a good starting inspiration for a DIY design. Then you can work up to making replacement 50uA FSD movements for Avo Model 8s.
Steve Conner, Fri May 13 2011, 12:25PM
The band is usually made of metal, not rubber. It isn't my idea, it is an industry standard design invented by Crompton or some such company.
The simplest meter movement is the cheap and nasty moving-magnet one found in car battery chargers, that would be a good starting inspiration for a DIY design. Then you can work up to making replacement 50uA FSD movements for Avo Model 8s.
Re: Where to procure meters?
Ash Small, Fri May 13 2011, 01:06PM
That's what I had in mind when I suggested it to Magnet18.
I'm sure I could build replacements for AVO's, but I couldn't afford the advertising campaign necessary to capitalise on it.
I also don't have anything accurate enough to calibrate it against.
Ash Small, Fri May 13 2011, 01:06PM
Steve McConner wrote ...
The simplest meter movement is the cheap and nasty moving-magnet one found in car battery chargers, that would be a good starting inspiration for a DIY design.
The simplest meter movement is the cheap and nasty moving-magnet one found in car battery chargers, that would be a good starting inspiration for a DIY design.
That's what I had in mind when I suggested it to Magnet18.
I'm sure I could build replacements for AVO's, but I couldn't afford the advertising campaign necessary to capitalise on it.
I also don't have anything accurate enough to calibrate it against.
Re: Where to procure meters?
uzzors2k, Thu May 19 2011, 07:31PM
Here's your opportunity: I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.
uzzors2k, Thu May 19 2011, 07:31PM
Here's your opportunity:
I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.Re: Where to procure meters?
Ash Small, Thu May 19 2011, 08:02PM
250 uA FSD +-10%. You could probably improve the accuracy using resistors if required.
Ash Small, Thu May 19 2011, 08:02PM
Uzzors wrote ...
Here's your opportunity: I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.
Here's your opportunity:
I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.250 uA FSD +-10%. You could probably improve the accuracy using resistors if required.
Re: Where to procure meters?
klugesmith, Thu May 19 2011, 08:04PM
Yes, what Uzzors said. It's silly to make analog meters from scratch (except as an exercise).
But not hard to computer-print and attach your own scale cards (e.g. 0-110 volts AC, 0-5 amps DC). The meters are all the same inside, except for series or parallel resistors (and in the AC case, diodes) which you can add by yourself.
p.s. I'm another happy customer of "kwtubes" on ebay.
klugesmith, Thu May 19 2011, 08:04PM
Uzzors wrote ...
Here's your opportunity: I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.
Here's your opportunity:
I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch. Yes, what Uzzors said. It's silly to make analog meters from scratch (except as an exercise).
But not hard to computer-print and attach your own scale cards (e.g. 0-110 volts AC, 0-5 amps DC). The meters are all the same inside, except for series or parallel resistors (and in the AC case, diodes) which you can add by yourself.
p.s. I'm another happy customer of "kwtubes" on ebay.
Re: Where to procure meters?
Ash Small, Thu May 19 2011, 11:28PM
I agree
But if you have no money you have no choice.
Total cost of these is ~$35 and they will still need resistors to calibrate to the required ranges, and to achieve accuracy greater than 10%.
They are still 250 uA FSD, but I'd agree this is the way to go.
I did consider suggesting trying to obtain meters from old cassette players, but thought this might not be very productive, plus they are quite small.
BTW I'm planning to get some neodymium magnets from Maplin next week. ~£1.50 each, so I can 'knock up' some larger, more accurate meters, just to prove a point.
I would advise Magnet18 that if he has $35 he should buy the ones Uzzor's reccommended, though......and obtain plenty of resistors.....
Ash Small, Thu May 19 2011, 11:28PM
Klugesmith wrote ...
Yes, what Uzzors said. It's silly to make analog meters from scratch (except as an exercise).
But not hard to computer-print and attach your own scale cards (e.g. 0-110 volts AC, 0-5 amps DC). The meters are all the same inside, except for series or parallel resistors (and in the AC case, diodes) which you can add by yourself.
p.s. I'm another happy customer of "kwtubes" on ebay.
Uzzors wrote ...
Here's your opportunity: I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.
Here's your opportunity:
I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch. Yes, what Uzzors said. It's silly to make analog meters from scratch (except as an exercise).
But not hard to computer-print and attach your own scale cards (e.g. 0-110 volts AC, 0-5 amps DC). The meters are all the same inside, except for series or parallel resistors (and in the AC case, diodes) which you can add by yourself.
p.s. I'm another happy customer of "kwtubes" on ebay.
I agree
But if you have no money you have no choice.
Total cost of these is ~$35 and they will still need resistors to calibrate to the required ranges, and to achieve accuracy greater than 10%.
They are still 250 uA FSD, but I'd agree this is the way to go.
I did consider suggesting trying to obtain meters from old cassette players, but thought this might not be very productive, plus they are quite small.
BTW I'm planning to get some neodymium magnets from Maplin next week. ~£1.50 each, so I can 'knock up' some larger, more accurate meters, just to prove a point.
I would advise Magnet18 that if he has $35 he should buy the ones Uzzor's reccommended, though......and obtain plenty of resistors.....
Re: Where to procure meters?
magnet18, Thu May 19 2011, 11:36PM
HUZZAWAAH!! :D:D
Don't expect to see these for sale tomorrow :D
magnet18, Thu May 19 2011, 11:36PM
Uzzors wrote ...
Here's your opportunity: I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.
Here's your opportunity:
I'd rather spend my time scaling a bunch of micro-ammeters to whatever ranges I needed rather than make fifteen from scratch.HUZZAWAAH!! :D:D
Don't expect to see these for sale tomorrow :D
Re: Where to procure meters?
klugesmith, Fri May 20 2011, 01:42AM
It's worthwhile noting that "Magic Eye" tubes, used as signal strength meters in pre-transistor radios and tape recorders, were cheaper than mechanical meters.
(image credit: Ake Holm)
If you already have the infrastructure to produce vacuum tubes, and the equipment already has appropriate filament and anode voltages, then a magic eye is just a few bits of welded wire and sheet metal in a glass bulb. Inherently well matched to the signal voltages and impedances, with no magnets, bearings, springs, coils, pointers, lamps, ...
[edit] and I guess mechanical meters had plenty of cost-reductions not yet invented.
klugesmith, Fri May 20 2011, 01:42AM
Ash Small wrote ...
... But if you have no money you have no choice.
... Total cost of these is ~$35 and they will still need resistors to calibrate to the required ranges, and to achieve accuracy greater than 10%. ...
... But if you have no money you have no choice.
... Total cost of these is ~$35 and they will still need resistors to calibrate to the required ranges, and to achieve accuracy greater than 10%. ...
It's worthwhile noting that "Magic Eye" tubes, used as signal strength meters in pre-transistor radios and tape recorders, were cheaper than mechanical meters.
(image credit: Ake Holm)
If you already have the infrastructure to produce vacuum tubes, and the equipment already has appropriate filament and anode voltages, then a magic eye is just a few bits of welded wire and sheet metal in a glass bulb. Inherently well matched to the signal voltages and impedances, with no magnets, bearings, springs, coils, pointers, lamps, ...
[edit] and I guess mechanical meters had plenty of cost-reductions not yet invented.
Re: Where to procure meters?
magnet18, Fri May 20 2011, 01:46AM
Pac man?
And unfortunately, I have no possible way to produce vacuum tubes anytime soon.
magnet18, Fri May 20 2011, 01:46AM
Pac man?
And unfortunately, I have no possible way to produce vacuum tubes anytime soon.
Re: Where to procure meters?
magnet18, Sat Jun 04 2011, 08:05PM
Awesome, 15 meters just arrived from lithuania...
Now I just need to switch some resistors...
magnet18, Sat Jun 04 2011, 08:05PM
Awesome, 15 meters just arrived from lithuania...
Now I just need to switch some resistors...
Re: Where to procure meters?
Conundrum, Sat Jun 04 2011, 09:29PM
Guys, if anyone is interested I have the following for sale/trade.
Eight or so long thin NIB magnets, suitable for DIY meters.
Some surplus 2.5" and 1.8" HDD mechanisms including the ribbon and magnets.
Various nice round panel meters, one with zero + - (centred), and some random salvaged old school voltmeters and ammeters which may be repairable if you have the time.
The paper scales need replacing but at least two work.
Due to unforeseen godzillabill I am happy to trade or sell these, you will need to pay postage however.
Please PM me for pics and full list.
EDIT:- A "Ghetto" hack for those who like that cool green CRT glow is to obtain a surplus G0 NV tube, as these are sensitive to infrared.
Install array of infrared LEDs behind a Nokia 3310 screen and you can write custom characters including that magic eye that looks so cool.
Even better these tubes do not get screen burn, and the required drive current is in the microamps.
Catch is they need 12KV IIRC but they are available really cheap to free because to use them as NV requires ridiculous levels of infrared making them worthless for their intended application.
Regards, -Andre
Conundrum, Sat Jun 04 2011, 09:29PM
Guys, if anyone is interested I have the following for sale/trade.
Eight or so long thin NIB magnets, suitable for DIY meters.
Some surplus 2.5" and 1.8" HDD mechanisms including the ribbon and magnets.
Various nice round panel meters, one with zero + - (centred), and some random salvaged old school voltmeters and ammeters which may be repairable if you have the time.
The paper scales need replacing but at least two work.
Due to unforeseen godzillabill I am happy to trade or sell these, you will need to pay postage however.
Please PM me for pics and full list.
EDIT:- A "Ghetto" hack for those who like that cool green CRT glow is to obtain a surplus G0 NV tube, as these are sensitive to infrared.
Install array of infrared LEDs behind a Nokia 3310 screen and you can write custom characters including that magic eye that looks so cool.
Even better these tubes do not get screen burn, and the required drive current is in the microamps.
Catch is they need 12KV IIRC but they are available really cheap to free because to use them as NV requires ridiculous levels of infrared making them worthless for their intended application.
Regards, -Andre
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