Affordable 4-digit panel meters?

I can find lots of LCD & LED 3-1/2 panel meters for under US$20. But look for
4 digits and the price triples.
Is this just my experience, or is this pretty standard pricing?
I'm flexible re. type (prefer LCD), background lighting (not necessary),
color (prefer green), and size (have ~25mm x 50mm panel openings waiting to
be filled).
I've looked at Mouser & Digikey. Spendy!
Where else to look?
Thanks,
Reply to
Usual Suspect
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I'd appreciate knowing your sources on the 3 1/2 digit panel meters that you have first hand experience. Basically overall quality of construction, did they ship any duds, stuff like that.
Reply to
miso
There is a "PM328" DPM that is available for under $20:
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Perhaps this is the manufacturer:
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Reply to
David DiGiacomo
I would say that the $20 meters you found were probably not "standard pricing" but were probably no-names.
Very very few real-world applications can use the extra digits usefully. There are some customers that really need it, but most customers demanding more digits are on an ego-trip :-).
The demand for standalone meters seems to be getting smaller and smaller as everyone moves to microcontrollers and commodity A/D that actually matches the resolution/accuracy needed. If you need isolation then you have to think a bit. In a lot of one-off applications it doesn't pay to think, you just buy the standalone meter!
Tim.
Reply to
Tim Shoppa
Want to replace the analog meters in my bench PS with digits. It goes beyond 20, so I'll need 4-digit meters, yes? I'd like more than 1 decimal place.
Maybe I've got it wrong... How do these meters work? Do they show the max decimal places possible (
Reply to
Usual Suspect
Typically the surplus 3.5 or 4.5 digit DPM unit itself is either 0-2V full scale, or 0-200mV full scale.
Some units can be jumpered for either, and some other ranges (including current ranges) are available. If you buy from a distributor you will have much better choice of ranges compared to buying a surplus unit.
You are responsible for adding the dividers/shunts if you want, and you are responsible for putting the decimal point where you want.
If you want 0.1V resolution, then a 3.5 digit meter gets 0.1V through 199.9V. Or at 0.01V resolution, a 3.5 digit meter gets 0.01V through 19.99V. As commonly incorporated into low-end power supplies, you might find a slide switch that changes the divider and the decimal point.
I would seriously question the need (other than "ego trip") of going to a 4 digit meter. Especially if (for example) you aren't buying 0.1% or better resistors for your divider or shunt already.
You also may have to look at where the power to the DPM module is coming from if you do not have a separate isolated power source just for the meter and you need to float the meter reference above ground. One often-seen option is a battery.
Tim.
Reply to
Tim Shoppa
"Tim Shoppa" wrote in news: snipped-for-privacy@o5g2000hsb.googlegroups.com:
If you are powering from the same regulator that powers a sensitive circuit that is outputting millvolts for measurement, take care, especially if you're using an LED meter. The meter can change the load, the load regulation might allow the other circuit's output to change, in turn changing the meter reading...
The easiest way to avoid this really vicious cycle is to use separate regulation for the meter and the measured, or even to isolate them with separate transformer windings, if battery power is not important.
There may be other, better advise to come on this subject. I hope so, cos I'll be watching it avidly if there is.
Reply to
Lostgallifreyan
I have some PM128 3 1/2 digit panel meters for sale @ $12.00 + shipping.
Listing on my web site at:
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Ed, W1AAZ
Reply to
Ed
__________________________________________
Why over work the human operator ? Use a ARM STR710FZ2T6 mcu.. Thats what im doin .
I will hook my MFJ209 to it and create a DMM . A super MultiMeter ... Test Coax , read the true inductance and capactance and Q .....read real stuff as the circuit is actually working ...
Reply to
Werty
Since this is apparently a one-off, observe that MPJA has 4-1/2 digits for $18.95
Reply to
zwsdotcom

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