[iScream]

Hey,

As I've been luriking around here and making big DIY plans, I've assumed that my old GoldStar DM-241 will do whatever I need. It has a fet tester, so I can do matching if needed. I started thinking about it tonight though and I'm not so sure now. I bought this thing back around 1994, and it's only been used a couple times a year since about 1996. It's never been calibrated.

So, what do you guys think? Should I drop it off somewhere and have it calibrated or just toss it out and get a new one? How much does it cost to have a DMM calibrated? What cool new things can you do with a DMM today that wasn't common 10 years ago?

Thanks for any advice.

-Chris

 

[Garbz]

Calibrated? My Multimetre has never been calibrated. It cost me $10 about 10 years ago and works perfectly. It may not get the centre of the value correct but it gets the differences right. So when you are trying to match resistors 499ohm may be 501 ohm but you can be damn certain that 500ohm readings are 1ohm higher. (That was the worst possible explaination of what I was trying to say

)

Anyway it's never let me down and the only time it has is when I've needed a CRO anyway.

 

[ATAT]

Yeah.. havent needed high precision multimeters.. Hfe matching isn't that accurate, resistor matching isn't that important (just get better tolerance resistors =p)

 

[Voodoochile]

As garbz mentioned, the consistency is more important than the absolute accuracy, as far as resistor matching goes. Having a 1K resistor versus a 997.967 ohm resistor is less important than having the left and right channels match within reason.

 

[ATAT]

oh and as to new features, all I can think of is temprature =p DMMs really dont change much..

 

[iScream]

Thanks everybody. Sounds like a few bucks I can spend on nice caps or something instead of a new DMM...

-Chris

 

[tangent]

DMM calibration costs about $50 for a meter at the low end of the quality lines, such as Fluke. Therefore, it really doesn't make sense to calibrate anything costing less than about $100. Indeed, a cheaper meter probably cannot be calibrated in the first place...they're not designed for it.

 

[ericj]

Quote:

Originally Posted by tangent DMM calibration costs about $50 for a meter at the low end of the quality lines, such as Fluke. Therefore, it really doesn't make sense to calibrate anything costing less than about $100. Indeed, a cheaper meter probably cannot be calibrated in the first place...they're not designed for it.

The Sneers Crapsman dmm that appears internally to be a Fluke 15b can be calibrated, and you can get them on ebay for about $25.

In fact, if you search fluke's website for that model, the only thing you can find is the calibration instructions in a PDF.

I don't think Fluke made this meter. Fluke meters are made in washington state and have a custom ASIC in them. The Craftsman in question has the same ASIC as found in Extech meters, and was manufactured in china.

If you search for "fluke 15b" on ebay, the only listing is a seller in hong kong who says it's made by "Fluke China".

I believe this meter was manufactured by Extech for Fluke, since it's much higher quality than the average extech. But it's not really a Fluke.

It's really pretty good for $25.

ANYhoo, among the things you can potentially get in a new meter - I have no idea what the goldstar meter offers, but nicer meters have more usable AC miliamps, and you can get them with frequency counters, and capacitance and inductance functions.

My Wavetek goes up to 20,000uf and 20H. And lacks volt and amp features.

My Mastech DMM claims to count up to 2mhz. So far I've only used it in double digits of khz, and it's basically accurate vs. what i was trying to do with a 555.

There are also DMMs with sound and light meters, but what the heck for?

And finally, for basic uses, Harbor Freight has a cheezy Cen-Tech on sale for $3.