Hi Rich,
I can agree. I'll add that backlit LCD panels are very legible from a distance and from reasonable viewing angles.
I wish LEDs back in the 1970's were as reliable as they are today.
Things with short service spans are the new target, like Cell Phones. I've been told by OLED manufacturers that I shouldn't expect them to last as long as LCD types at this point in time. Who knows?
It blows me away that we know how, and can manufacturer things to last decades. Manufacturers choose to make short term junk. At some point we need to object vigorously.
I can agree. I'll add that backlit LCD panels are very legible from a distance and from reasonable viewing angles.
I wish LEDs back in the 1970's were as reliable as they are today.
Things with short service spans are the new target, like Cell Phones. I've been told by OLED manufacturers that I shouldn't expect them to last as long as LCD types at this point in time. Who knows?
It blows me away that we know how, and can manufacturer things to last decades. Manufacturers choose to make short term junk. At some point we need to object vigorously.
This is the DVM I use every day:-
However the 8050A on my workbench has more resolution.
For example I just measured a 9 Volt battery:
Fluke 79........................................9.33
Fluke 8050A..................................9.333
Slumberger Solartron 7075.............9.32577
The Fluke 79 has seen many years of daily use and works the same as ever. The casing is cracked and glued back together here and there but still working!
However the 8050A on my workbench has more resolution.
For example I just measured a 9 Volt battery:
Fluke 79........................................9.33
Fluke 8050A..................................9.333
Slumberger Solartron 7075.............9.32577
The Fluke 79 has seen many years of daily use and works the same as ever. The casing is cracked and glued back together here and there but still working!
It depended who made them LED 7seg displays used industrially made by HP or similar were reliable, but the market was soon flooded by cheap consumer electronics, calculators, digital alarm clocks etc and the LED 7seg displays were not so reliable.
The magnified LED displays you mentioned were hand manufactured (you could see the wires) and as you say segments stopped working.
Just a suggestion. Never leave batteries in a DVM (or other equipment) unless you check
the batteries regularly for leakage. Even if they are "leak-proof" batteries. There's no such thing.
the batteries regularly for leakage. Even if they are "leak-proof" batteries. There's no such thing.
Monocolor OLED is short in lifetime. No comparison with decades old LED displays. I have already seen failing ones in less than a years use.
Agree 100% - often come across equipment that has been damaged in this way. To reduce the risk I have a 9V rechargeable NiMh battery for my Fluke 79. This battery has seven small diameter tubular batteries inside a plastic casing, so I think the risk is reduced.
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Duracell are the worst. They will leak with full battery voltage and have for decades. Yank them, use Eveready Alkaline. Absolutely, pull batteries from stored equipment.
No battery is leak-proof. Some just have a reputation for leaking often.
Hi Rich,
Yup, I have a Fluke 79 and some others. Great meters. They will hold their calibration very well. Many other brands do not. My HP 974A meters (3) have always been in tolerance, as have my 34401A meters. The Fluke handhelds have also always been in tolerance. I've seen many cheaper meters out of tolerance (new out of the box), and some could not be adjusted to be in spec. No cert. for them. Imagine how many folks buy meters and assume they are accurate. Then there is the aging thing with calibration.
If you look at the accuracy specs and calculate an error budget, you may find the last digit is pure fiction with most low cost meters.
No battery is leak-proof. Some just have a reputation for leaking often.
Hi Rich,
Yup, I have a Fluke 79 and some others. Great meters. They will hold their calibration very well. Many other brands do not. My HP 974A meters (3) have always been in tolerance, as have my 34401A meters. The Fluke handhelds have also always been in tolerance. I've seen many cheaper meters out of tolerance (new out of the box), and some could not be adjusted to be in spec. No cert. for them. Imagine how many folks buy meters and assume they are accurate. Then there is the aging thing with calibration.
If you look at the accuracy specs and calculate an error budget, you may find the last digit is pure fiction with most low cost meters.
Maybe it depends on color (and brand probably) but the blue ones have missing/fading pixels quite soon.
Yes. Volts is perhaps the hardest to know with certainty. My Slumberger Solartron 7075 has a standard that's kept at a constant temperature in a small oven but even then. Another simple way to check is to measure the voltage across a very accurate voltage reference chip made by Analog Devices.
Its rarely a problem.
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Hi Rich,
Not for you. But others simply read whatever is on the screen.
My new Keysight meters also keep the voltage reference in an oven that is on all the time. Cross checks help confidence as well as those simple voltage reference chips. The ref inside a 3458A are expensive as sin!
Not for you. But others simply read whatever is on the screen.
My new Keysight meters also keep the voltage reference in an oven that is on all the time. Cross checks help confidence as well as those simple voltage reference chips. The ref inside a 3458A are expensive as sin!
Just flip the polarizing sheet from an old calculator to get reverse effect on LCD (bright becomes dark). Much easier to read in some conditions.
LCD compatible with 7106 are pretty common; just search for it.
And a really cheap DMM is like $2 here, a meter with needle reading volts can be around 50 cents here, you could salvage the volt meter from a car or truck, good enough for seeing what is going on in a solar panel...pretty rugged too.
The 7107 (LED version of 7106) is very much used in temperature controllers, gradually going obsolete. About $0.40 here, seems the pin outs are same for the two chips...
And meter modules are cheap, $2.50 here last I checked, they are supply powered, no battery / PSU needed. Smallest is about 20 mm, fits in holes for panel indicators.
LCD compatible with 7106 are pretty common; just search for it.
And a really cheap DMM is like $2 here, a meter with needle reading volts can be around 50 cents here, you could salvage the volt meter from a car or truck, good enough for seeing what is going on in a solar panel...pretty rugged too.
The 7107 (LED version of 7106) is very much used in temperature controllers, gradually going obsolete. About $0.40 here, seems the pin outs are same for the two chips...
And meter modules are cheap, $2.50 here last I checked, they are supply powered, no battery / PSU needed. Smallest is about 20 mm, fits in holes for panel indicators.
Very useful post.
Yes the 7106 and 7107 are very versatile and reliable chips. Glad you still have use for them.
Using a 7106 as a 7107:-
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Absolutely, I still have a bunch of both.
They were the answer for an inexpensive meter option, you could use an external reference too.
They were the answer for an inexpensive meter option, you could use an external reference too.
I was told those chips originated at Fluke and ICL tweaked them to be able to sell without royalties.
The Fluke numbered chip is a close fit to the 7106 datasheet as regards pins, type of signals I didn't try comparing accuracy.
Hi Demian,
Now where is the real truth? That story could have gone either way. Fluke may have liked the chip and bought a tweaked version (increased accuracy for example). Voltmeter on a chip was a popular product when they came out, everyone was making them.
I was designing voltmeters at the time and still have a bunch of different chips and chip sets. One big improvement was using an external voltage reference, especially for the 7107 LED version as the chip temperature can change depending on the display reading. Many other chips used an external display driver for that reason.
Now where is the real truth? That story could have gone either way. Fluke may have liked the chip and bought a tweaked version (increased accuracy for example). Voltmeter on a chip was a popular product when they came out, everyone was making them.
I was designing voltmeters at the time and still have a bunch of different chips and chip sets. One big improvement was using an external voltage reference, especially for the 7107 LED version as the chip temperature can change depending on the display reading. Many other chips used an external display driver for that reason.
A little history: https://pa3fwm.nl/technotes/tn27a-voltmeter.html
And a little more form a real source: https://www.eevblog.com/forum/testgear/old-fluke-multimeters/
And a little more form a real source: https://www.eevblog.com/forum/testgear/old-fluke-multimeters/