Need precision divider resistors

Phil Pilgrim (PhiPi)

A friend of mine is refurbishing a large vessel for commercial fishing. He bought a digital panel meter that accepts voltage inputs to 200mV full scale. He needs 2V full scale. The module includes pads for a voltage divider, along with decimal-point-selector pads. To accomplish his requirements, the doc sheet that came with the meter specifies two ½W, 0.05%, metal-film resistors valued at 1 Megohm and 9 Megohms. Surely DigiKey or Mouser must have such things in their immense Ohmic bestiaries, right?

Nope. I'm at a loss. Any ideas where I can find such resistors in stock and ready to ship in onesie-twosie quantities?

Thanks,
-Phil

Publison

Best I could find quickly that may not work:

https://www.goldmine-elec-products.com/prodinfo.asp?number=G21520
https://www.goldmine-elec-products.com/prodinfo.asp?number=G22848

in series.

.05% seems pretty tight for a panel meter.

Tracy Allen

Caddock type 1776 at Mouser.

Phil Pilgrim (PhiPi)

Thanks for checking. The 9M resistor is the real stinker, I'm afraid. My temptation is just to buy 200 1% or 5% resistors and check them all with my Agilent ohmmeter to find the closest candidates. Of course, that doesn't do anything to alleviate bad tempco specs.

-Phil

Tracy Allen

Also, http://www.caddock.com/Online_catalog/Mrktg_Lit/Type1776.pdf
Digikey has them too. You'd have to "bend" it to fit the existing pads.

Phil Pilgrim (PhiPi)

That's it! Thanks, Tracy! IIRC, I searched divider arrays but limited my search to those with three pins. D'oh!

-Phil

Tubular

Well, I learned something today already. These forums are invaluable

Tracy Allen

At $15, you get what you pay for!

Phil Pilgrim (PhiPi)

I think that's more than my friend paid for the panel meter module! But that's okay: it'll certainly do the job. And if he reimburses me in smoked salmon, even better!

-Phil

Tracy Allen

Indeed. And check out the sumergible pump on sale at goldmine-elec, to keep your salmon precisely fresh in the bucket before it reaches the smoker.

Phil Pilgrim (PhiPi)

Wow! That's a great price, and Rule is a respected brand of pumps.

-Phil

Phil Pilgrim (PhiPi)

Divider ordered. When I told my friend how much it cost, he said he wanted it mounted on the front panel so everyone could see it!

-Phil

Genetix

Phil,

More than likely that meter uses a 7106/7107 as do a lot of cheap meters.

Phil Pilgrim (PhiPi)

It uses a GC7129BD.

-Phil

jmg

Phil Pilgrim (PhiPi) wrote: »

... the doc sheet that came with the meter specifies two ½W, 0.05%, metal-film resistors valued at 1 Megohm and 9 Megohms. ..

Does the meter have over 2,000M Ohms input impedance ?

Phil Pilgrim (PhiPi)

Input impedance is spec'd at ">100Mohms". And, yes, I do understand the reason for your question.

The module includes a trimpot to compensate for slight calibration discrepancies. I plan to use it, along with my Agilent precision voltmeter, to adjust the calibration over a range of inputs in order to minimize the RMS error.

-Phil