FS: strip chart recorders - could be useful for monitoring machine parameters?

ok, peak hold circuits use one or two op amps (depending on your preferences) and are shown in almost every op amp handbook I've ever looked at. Gunner is knowlegable enough to look at the op amp handbooks. If that information is not readily available, see figure 8.5 here

A two resistor divider network (would you like me to calculate the value for you?) will null out the nominal voltage if you want to preset a value. If you would rather not preset, but have the "average" calculated, a lowpass circuit with a time constant of 10 seronds will suffice if you are doing 1 or 2 minute samples. Would you like me to provide such a low pass circuit - again, these are in just about every handbook - takes one op amp, 3 resistors and one capacitor if you use the inverting configuration with unity gain, one more resistor if you want non inverting.

Subtract the lowpassed "average" value from the line voltage (divided 10 to

1) (one op amp, 4 resistors, all 10K) to get a delta value. Make two of the peak hold circuits, configure one to hold positive peaks, one to hold negative peaks. reset each time you take a sample.

Power line input - 100K, 10K, diode, .01 uf cap to get lightly filtered input - use bridge if desired.

this is trivial op amp circuitry. to implement it would require a total of one chip -

If there is really a need for me to sketch this out, I'll do it and drop it into the drop box, but I think this is just being argumentative - If gunner really needs the schematic, he knows how to ask me.

I'm sure he does, and I certainly don't wish to be argumentative.

BTW, if you add one more cap to your lowpass you can make it a Sallen-Key topology with second-order Butterworth response. Much better performance.

Hi DoN,

That sounds like the same unit. It must have weighed over

200 lbs and took some serious sized batteries.

Have you got the manual for your unit? Most of the fault and reporting parameters were programmable on this one. You could set it to run if say the freq varied by more than 1.5 hz or some such value (it was a long time ago...). It even could tell you the ambient temperature when asked and that value could be set to alarm on too.

I wondered if you were okay or not. I hadn't seen any recent postings from you. I'm glad to hear it was just news server problem and not something more serious.

I certainly like this one

?product_id=2078&czuid=1168110516983

And I can rent it for only $400 a month!!!

Now my mortage payment was only $320 a month..so it sounds like a real winner!!

HUMMM!!! Actually..I DO have a couple APCs with 9 pin connectors on the back!

Ill damned sure check into this!

Thanks!

Gunner

"Deep in her heart, every moslem woman yearns to show us her t*ts" John Griffin

[ ... ]

I think that mine is closer to 600 pounds. It was a serious job winching it up through the trapdoor into the room where my computers live.

Yes -- sort of a generic manual for the whole series, but that can be downloaded these days.

The ambient temp was that in the UPS, not outside. :-)

So am I. Things are not really fully right again -- at least based on last night's experience. I've been on a phone call for a couple of hours while typing this.

Enjoy, DoN.