Where are all the ESR meters?

What meter?

John

You just put a restriction on that I don't like. To connect to a DVM we have to make a voltage that is proportional to the ESR. This requirement would add quite a few parts to some peoples ideas.

Nice try, Fred, but you have no idea what you're talking about. First of all, you have to be a member of this prepaid dental service group. Secondly, there are no oral surgeons in my area that belong to this plan.

There are only two offices listed, one of which I had under my former HMO plan. They don't do much more than clean teeth and do minor fillings. If you badger them long enough, you might get a referral to a oral surgeon.

The other office does braces and teeth cleaning. That's all.

I see Code 7241 is $170 for the type of oral surgery that I have to have.

Most of these plans limit you to one extraction, per visit. Some limit you to a couple, per year.

So, your final solution was a no go from every angle.

Don't you think I looked long and hard at the options? Unlike you, I have a personal stake in my life. I have visited hundreds of dental related websites, made calls and visited in person in an attempt to resolve my problem. I have been through every organization dealing with dentistry in the state of Florida, and a dentist friend in California made a lot of calls to try to help, through his resources.

Your usual blind hatred of me doesn't help, at all.

Probably the one he didn't design because he can't risk it being critisized.

The one he won't show us, because we're not worthy.

John

Does he remind you of the pompous ass doctor on M*A*S*H? Major Charles Emerson Winchester, the turd? Not as good as he thought he was, but always too big of an ass to admit his mistakes?

Come to think of it, Fred is trying to practice medicine online. Do you think.....?

Winchester was at least competent and didn't mind showing it. OTOH, Frank Burns comes to mind. ...or maybe Margaret.

Frank is more like Phil or Eeyore. Margaret did let her guard down at times, long enough to show she really was human, in spite of having to cope with the madness around her. Everyone has different ways of coping with disaster, and a MASH unit was as close to hell as anyone would want to get.

Maybe Col. Flagg, AKA 'The wind' is closer? Paranoid as hell, and didn't give a damn about anyone.

A sliding sleeve on the probe can activate the switch, if you like that approach, or your foot switch idea, or tweezer style probes, or whatever peple come up with. Some people may want to test uninstalled caps - I imagine all kinds of "test jigs" could be desireable.

Ed

The one you're not going to see...

You are a beggar and therefore not entitled to be picky. You will get the simple tooth extraction for $30 and no more.

It makes no difference how hard you tried when the end result is failure to achieve results...

You must be confusing me with your neighbors who seem to hate you on sight.

OK, here's a block diagram for my esr-meter design, from my scratchpad. Detailed circuit portions can be posted later.

Running things off a 3-0-3 (6V centre-tapped) supply is so restrictive though...........

Yes, a point of debate. The merits of the ratiometric facilities of a DPM versus an analogue divider.

At the back of my mind in making the remarks were several possibilities. Having more power from an AC supply would allow much more freedom in the design itself, including the power to drive relays. The interesting relay could be a 4PCO that shifted the front end connections from a Discharge mode to the ESR Measurement mode. The relay would come up unpowered, in the Discharge position and, (when seen to be safe), a push button would latch the relay over to make the input connections for Measurement.

When in Discharge mode the meter, (or external DMM/DVM), could be switched to look at the (discharging) DC voltage across the capacitor under test.

From that pov the analogue divider in the ESR chain would make more sense than a ratiometric DPM.

Batteries do come in shapes and sizes. A lead acid battery I can easily lift will provide more power for a short time than a wall wart. Whatever voltages are needed can be made with DC-DC converters. As a result, I suggest we let the issue of the battery float and think in terms of how much power is needed. Once we know the answers on power and voltages, we can design the power supply part of the system.

I don't like trusting the relay to not be in the measure position when the battery is charged. I think it makes more sense to design the circuit touse semiconductor devices to do the discharging when needed.

But the question is, why dischare?

We may not need to make a sine wave to feed the capacitor. The first is the way I was thinking of the design. I will simplifiy the idea so the ASCII art is simple. Consider this graph:

....*********** Current ....*.......... *****.......... ............... ..............* ....*........*! ....*.......*.! V-Cap ....*......*!.! ....**....*.!.! *...**...*..!.! .*..*.*.*...!.! ..*.*.**!...!.! ...*....!...!.! ........!...!.! TimeA ........*****.! ********!...!.! ........!...!.! TimeB ........!...*** ************!.! ........!...!.!

----!!----- ! ! TimeA-------- +---/\\/\\----+ ! ! ! Vcap--------/ O----/\\/\\----+---+---!-\\ ! ! ! >----+--- TimeB-------- ! !+/ ! ! -N*Vcap-----/ O----/\\/\\----

By grabbing the voltage starting some time after the ESL stuff has died down and some later time, the slope due to the capacitance can be removed.

Now for a variation of your design:

We are after the portion of the voltage on the capacitor that is in phase with the drive signal. The frequency components of the signal on the capacitor will all be lined up so that a gain that goes -1, 0,

Did you see the stuff I posted to abse? It was like this, but I assumed a uP and an adc, taking a lot of samples on the cap charging ramp, and doing some math to derive C and ESR.

Win stated that he didn't want a uP, which is fair, but being able to do some computation would simplify the hardware and allow better accuracy. Variable frequency would be nice, too.

John

Why are we not shocked? Why are we not disappointed?

Why are we snickering?

John