Extech LCR Primer?

[PoorMan]

Can anyone give me a quick rundown on these things and the benefits of having one relative to winding? I believe they can measure resonant peak (amongst other things)? Are they user friendly? I know pretty much zero about them.

Thanks!

[DrStrangelove]

QC

Can anyone give me a quick rundown on these things and the benefits of having one relative to winding? I believe they can measure resonant peak (amongst other things)? Are they user friendly?

They're friendly enough. The benefit is better quality control; they measure inductance and AC resistance which can indicate problems that a DC ohmmeter can't show.

The Extech doesn't do resonant peak measurements but it determines Q-factor at the test frequency (100 and/or 1000Hz).

-drh

[SkinnyWire]

They're easy to use and accurate. You don't need one, but they're handy for providing additional parameters to check against as you build similar types repeatedly and they're a good tool when spec'ing pickups sent in for rewind or blueprinting.

I believe a thread on the old board explained how they can be used to measure DC resistance as well, but at 120 Hz it will give you an indication if you're way off with your DVM. For example, I've got a pickup in for blueprinting right now and the guy said it was 8.3k. My DVM says it's 8.15k and the Extech says at 120Hz it's 8.2-ish (don't recall the exact value, but under 8.3k). It's normal for it to read a bit higher since it's not a DC measurement.

Having the inductance gets you one step closer to determining the resonant frequency and saves you having to set up a rig to determine the inductance "manually/by calculation". The one thing I haven't figured out is if the capacitance measurements are at all meaningful as relates to a humbucker. However, individual coil inductance both unloaded (no steel) and loaded as well as overall inductance are things I check with every coil to determine how well I'm doing at reproducing each wind.

It's a nice piece of equipment, and you should be able to write it off on your taxes.

[Joe Gwinn]

Having the inductance gets you one step closer to determining the resonant frequency and saves you having to set up a rig to determine the inductance "manually/by calculation". The one thing I haven't figured out is if the capacitance measurements are at all meaningful as relates to a humbucker.

Extech capacitance measurements on a pickup are not simply meaningless, they are complete nonsense. This is not a problem with the Extech.

[SkinnyWire]

Extech capacitance measurements on a pickup are not simply meaningless, they are complete nonsense. This is not a problem with the Extech.

Sorry for the confusion. I didn't mean to hint that it was a problem with the meter itself, just that measurement results didn't seem to mean a whole lot vis-a-vis capacitance when measuring pickup coils.

I think you had posted the method for calculating distributed capacitance a couple of years back, which is what I was comparing against when I got the Extech. I chose to trust the math, not the meter.

To be clear, I think the meter is great. Anything that can make things easier to do and at a reasonable cost is a good thing.

[Joe Gwinn]

Sorry for the confusion. I didn't mean to hint that it was a problem with the meter itself, just that measurement results didn't seem to mean a whole lot vis-a-vis capacitance when measuring pickup coils.

I didn't take it as a criticism of the meter, but wanted to head off that theory. No such meter can measure the self-capacitance of an inductor below resonance, and the meter has no way to tell what's hooked to its terminals aside from what the user tells it by punching buttons on the panel.

[mick]

While we are on the subject of measurements and such , do any of you have your room at a constant temperature...? because as we know temp can change your readings a bit....not sure if the world wide engineering std applies here but it's a thought....

Mick

[Spence]

I wouldn't get bogged down with all that crap. Generally people want a great sound and couldn't give a shit about accuracy to the 3rd decimal. For those with 3rd decimal accuracy syndrome these is no cure that allows them to keep living but a swift kick to their testicles is an absolute tonic.

[SkinnyWire]

While we are on the subject of measurements and such , do any of you have your room at a constant temperature...? because as we know temp can change your readings a bit....not sure if the world wide engineering std applies here but it's a thought....

Mick

You're right. I keep my house/shop at a constant 73-74 degrees pretty much year around. Where I live, even winter time is in the 70s or better outside except for a few days out of the year so my air conditioner is on pretty much 24/7/365. Resistance appears to be much more temperature sensitive that inductance, and I NEVER take a reading for final spec of a pickup unless it's sat at room temperature for an hour or two after handling. Most often, I let them sit overnight. Not that it has to be done and has to be that accurate, but at least that way I know the conditions surrounding the measurements are consistent which makes it easier to spot anomalies.

[SkinnyWire]

I wouldn't get bogged down with all that crap. Generally people want a great sound and couldn't give a shit about accuracy to the 3rd decimal. For those with 3rd decimal accuracy syndrome these is no cure that allows them to keep living but a swift kick to their testicles is an absolute tonic.

You're right too. I don't know about others here, but I don't take the measurements for the customer. If the subject comes up, I let them know the bottom line on nth degree accuracy in readings. I take the measurements to tell me if something might be wrong with the coils/build and to learn a bit more about the process. I could just kick the pups out the door, and 99.999% of the time things would be fine. However, if somethings way "off" in the measurements I don't ship that coil/pickup. That way, I don't have to worry about returns and the specs give me good confidence that I've reproduced the great sound associated with the specs at hand (backed up by actual audible testing). I used to test every pickup I shipped in a guitar, but order volume soon made that unrealistic. Other peoples' testicles notwithstanding, this is the method I've developed for my own peace of mind. YMMV.

As regards the original topic, the Extech is a fine piece of equipment for the price and worth the scratch for a body interested in knowing a little bit more about what they're buidling.

[Possum]

@@@@@@

The Extech doesn't measure DC resistance, also it needs to be set to serial mode. They are useful if you need to duplicate pickups in production to check that you're in the ball park. They are also great for spotting coil shorts when sometimes a DC resistance reading won't. They are good learning tools to learn whats happening inside a coil especially if you change your winding pattern or are making an original pickup design and need to know what physical changes you make will effect what comes out of the coil into your amp. they are also great for A/B 'ing prototypes when some of them are very close to eachother and ears can't pick up the differences when ear fatigue and design burnout are in operation.....
These are also being discontinued, not being made anymore, I wonder if they are coming out with a newer better one

[soundmasterg]

Wow, they're being discontinued? Learn something new every day.....glad I got mine already!

Greg

[SkinnyWire]

The Extech doesn't measure DC resistance, also it needs to be set to serial mode. They are useful if you need to duplicate pickups in production to check that you're in the ball park. They are also great for spotting coil shorts when sometimes a DC resistance reading won't. They are good learning tools to learn whats happening inside a coil especially if you change your winding pattern or are making an original pickup design and need to know what physical changes you make will effect what comes out of the coil into your amp. they are also great for A/B 'ing prototypes when some of them are very close to eachother and ears can't pick up the differences when ear fatigue and design burnout are in operation.....
These are also being discontinued, not being made anymore, I wonder if they are coming out with a newer better one

Didn't know they were being discontinued either. Too bad. Maybe there's not a big enough market for them. Hope they're coming out with a newer one.

[soundmasterg]

Well I know that some manufacturers like Rickenbacker for instance do use the Extech also, so I can't imagine that they wouldn't have a replacement for it on plan.

Greg

[DrStrangelove]

Well I know that some manufacturers like Rickenbacker for instance do use the Extech also, so I can't imagine that they wouldn't have a replacement for it on plan.
Greg

Tecpel, a Taiwanese firm, sells an identical LCR meter.
http://www.tecpel.com/LCR_612.htm

So few things are made in the US anymore, I suspect
that Extech's meter is a rebranded one.

-drh