[guest1632]

Hi all,

I was givin some money to buy a Talking Multimeter. The neat thing is it has a capacitance bridge, and a frequency counter. Now the question.:

This particular meter will measure up to just under 400 Mils. Is that typical for any meter? I guess if you wanted to measure the current higher than 400 Mils, you'd have to use a set of resistors ahead of what you are measuring?

Ray

[JohnR]

Ray, I meant to find my meter and check its current capacity earlier today, but have failed. I assume you are asking about current measurement (400 mA max). Mine would be either 200 mA or 2A. A typical multimeter is simply not built to handle high currents.

In practice, for building DIY gear, I don't remember the last time I actually used current measurement. If you can measure a (differential) voltage and know a resistance value, the current is of course easily calculated. (For general work you don't need high precision.) If a higher current needs to be measured then a small resistor in the current path would be the way to do it. This is in fact how bias current in tube amps is measured, for instance.

[Dan Banquer]

Hi all,

I was givin some money to buy a Talking Multimeter. The neat thing is it has a capacitance bridge, and a frequency counter. Now the question.:

This particular meter will measure up to just under 400 Mils. Is that typical for any meter? I guess if you wanted to measure the current higher than 400 Mils, you'd have to use a set of resistors ahead of what you are measuring?

Ray

Many of the Fluke meters will measure up to 10 amps if I remember correctly,but please feel free to check their web site.
I would like to offer one word of advise to DIY folks. In many cases you really are better off spending more money on better test gear. I think good meters are one of them.
d.b.
             d.b.

[Gordy]

My Simpson 260 has four ranges: 500, 100, 10 and 1ma.  It also has probe sockets for 50u amps and 10 amps but, it's not a typical VOM and was given to me by a retiree 20 some years ago. 

[guest1632]

Hi all,

I was givin some money to buy a Talking Multimeter. The neat thing is it has a capacitance bridge, and a frequency counter. Now the question.:

This particular meter will measure up to just under 400 Mils. Is that typical for any meter? I guess if you wanted to measure the current higher than 400 Mils, you'd have to use a set of resistors ahead of what you are measuring?

Ray

Hi Dan,

You're probably right. Unfortunately, I have to get what is available. I think there is another Talking meter, but we're looking at something like $650 for it. This one is only $50. Don't know how good the accuracy is.

Ray
Many of the Fluke meters will measure up to 10 amps if I remember correctly,but please feel free to check their web site.
I would like to offer one word of advise to DIY folks. In many cases you really are better off spending more money on better test gear. I think good meters are one of them.
d.b.
             d.b.

[guest1632]

Ray, I meant to find my meter and check its current capacity earlier today, but have failed. I assume you are asking about current measurement (400 mA max). Mine would be either 200 mA or 2A. A typical multimeter is simply not built to handle high currents.

In practice, for building DIY gear, I don't remember the last time I actually used current measurement. If you can measure a (differential) voltage and know a resistance value, the current is of course easily calculated. (For general work you don't need high precision.) If a higher current needs to be measured then a small resistor in the current path would be the way to do it. This is in fact how bias current in tube amps is measured, for instance.

Hi John,

Thanks for the info. I've got to measure on my SS amp, the correct bias, which is about 150 Mils against a 10K Ohm set of resistors. So that's about right.

I do have a Radio Shack Talking meter. It's not working right. So I got this one instead. The Radshack meter I remember a bunch of hams had checked it out, and it wasn't that accurate. So hopefully this new one will be better.

Ray

[Dan Banquer]

If one of these is in your price range I would recommend it. Having an AC rms meter good from 20 Hz to 20 kHz sure comes in handy.
http://www.techni-tool.com/static-products/fluke/374TE087.html

d.b.

[samplesj]

If one of these is in your price range I would recommend it. Having an AC rms meter good from 20 Hz to 20 kHz sure comes in handy.
http://www.techni-tool.com/static-products/fluke/374TE087.html

d.b.

You keep missing that he is looking for an audible meter.  Ray has vison problems and can't see the screen on the ones you keep recommending.

[Dan Banquer]

If one of these is in your price range I would recommend it. Having an AC rms meter good from 20 Hz to 20 kHz sure comes in handy.
http://www.techni-tool.com/static-products/fluke/374TE087.html

d.b.

You keep missing that he is looking for an audible meter.  Ray has vison problems and can't see the screen on the ones you keep recommending.

Thank you for that bit of info, as I was totally unaware of this. Unfortunately  I know of nothing at the moment that would help here.

This is something I found in a google search: I hope this might be of some help. I will look more later on this week if I can. http://www.nfbcal.org/nfb-rd/0238.html

   d.b.

[art]

I would not advise trying to measure bias by using a current meter. It would be better to measure the voltage drop across the appropriate resistor in the circuit.

Pat

[jrebman]

As Ray now knows, I have an HHM2a from Omega Instruments which is a talking DMM with IR temperature measurement, true RMS AC voltage measurement from 20 Hz to 50 KHz (or maybe it is 50 Hz to 20 KHz), current measurment to 4 amps, DC voltage to 1000 and AC to 750.

Unfortunately, it is expensive, and also no longer made.  The company was also reluctant (and in fact wouldn't) sell me the meter because I am blind (despite my telling them that I am an EE and have extensive experience with HV power systems) and had to have my father order the meter for me.

There are various USB and PCI bus based A/D and instrumentation modules and supporting software, but these also tend to be expensive (though there are some less expensive USB scope modules that should also work as DMMs) but the problem here is that the accessibility of the control and measurement software is a total crap shoot as to whether or not it will actually work with a screen reader... and so far my experience is that most of them will not.

IBM does make a PC based electronics lab system for schools and universities that is supposed to be accessible with a screen reader, but from what I remember the system is pretty expensive.

I did some lab accommodation consulting for a blind EE student several years back at my local university and at the time most of the available solutions were either very expensive, too limited, or the screen reader support not there to make it practical to use.  Things may have changed since then, and I do have a couple of scope modules on my hit list to look into, but at this point there is nothing I can recommend beyond the $50 meter that both Ray and I have now.

It's kind of funny since I can get almost any other measuring tool I want -- digital micrometers, vernier calipers, scales, blah, blah, blah, but very little in the way of electrical equipment.  I guess blind folks are supposed to stick to mechanical things and stay away from electrical ones .

If I had a decent scope, an accurate and sensitive color detector, and a good way to work with tactile schematics I could be completely independent with my DIY projects.

I can't complain though because I'm sure things are much better now than they were 25 years or more ago.

-- Jim

[Dan Banquer]

There may be some additional possibilities here:
http://www.audiocircle.com/index.php?topic=43861.0

Your basic premise is sound: get the info onto a computer and go from there.
            d.b.

[guest1632]

There may be some additional possibilities here:
http://www.audiocircle.com/index.php?topic=43861.0

Your basic premise is sound: get the info onto a computer and go from there.
            d.b.

Thanks Dan.

Ray