I don't need no stinking calibration

[staxquad]

I don't need no stinking calibration






22*C, warm up > 8 hours

Prime Technology - General Resistance DAS-47AL, 7 digit 0 to 1V, 0 to 10V Kelvin Varley Divider
resolution 0.1 micro volt
accuracy 0.0015%
T.C. typical 0.7ppm/*C, max 1.5ppm/*C


can select either HP 3478A, connect the  +10V reference and it will not twitch for hours, steady +10.0000VDC
my Fluke 87III shows +9.996VDC

shielded Kelvin Varley Divider at the top and reference voltage adjust shielded box at the bottom


amplifier zero adjust at the top left corner


shielded transformer box

[ftransform]

are you working on an moth fart detector?

[staxquad]

are you working on an moth fart detector?

edit:  I'm still trying to figure out what you said.  So far, either you are saying the unit is old, or it's sensitive.  For old, I hope the unit carries on; for being sensitive, right now I only have confidence in 6 of the digits which only covers my meters, nothing more.   Hope to eventually check the unit on a calibrated meter to validate the 7 digits.

you don't eat pudding?

if you don't like old, you can still get it new, only $8570 (most likely updated circuitry), also constant current but only 6 digits

http://www.newark.com/shurite-meters/das-56a/das-56a-dial-a-source-general-resistance/dp/73K4753

http://www.primetechnology.com/PartsDetails.aspx?PartsId=144&Parentid=59&ParentType=C

http://www.primetechnology.com/cp/images/PartsDocument/83658.pdf

newer versions a little too rich for my blood at $500 used on ebay

[codeboy2k]

ok.. now you done it... you made me want to build one 

[staxquad]

ok.. now you done it... you made me want to build one 

the pdfs then

[edavid]

Does it buzz as much as my DAS-56A's do?  I can't leave them on, they drive me nuts.

[ltz2000]

Does it buzz as much as my DAS-56A's do?  I can't leave them on, they drive me nuts.

Last week I helped a friend who also has a loud Dial-A-Source.

There is no cure for the sound. The transformer key design parameter seems to be the low capacitive coupling and the quietness comes far behind.

if you don't like old, you can still get it new, only $8570

Doesn't surprise me at all. A real engineers daydream and assemblers nightmare. A number of small printed circuit boards here and there and maximum amount of wire between them. Full of tiny custom metal boxes and mounting brackets needed to solve the design flaws made in the earlier stage of the process.

most likely updated circuitry

Most likely not. The one that I tried to cure was built in the late 90s and looks exactly the same. Most of the parts from the 90s, modern looking solder masks etc. But here and there components, like operational amplifiers and transistors, from the early 80s or even late 70s.

The electrical safety was horrible. Doll house wire used for the internal mains connections. Which were of course tied together with the sensitive low voltage DC wiring. A live turret pin was so close to the metal enclosure wall that I needed an ohmmeter to see if it makes a connection or not. The gap was too tight for a piece of paper.

[Vgkid]

Show us the KVD already, that is what we really want to see.

[ltz2000]

Show us the KVD already, that is what we really want to see.

Nothing special. Thumb wheel switches, ten resistors soldered on each of them. The resistors are good stuff *, General Resistance brand of course.

http://www.primetechnology.com/cp/images/PartsDocument/163323.pdf

* EDIT: If you don't ask Mr. Pettis.

[mtdoc]

Very nice.  Looks like there's a DAS-46 on ebay right now for $149.  No DAS-47 though.

We don't need no stinking calibration - Ha!  I can't resist:

[fivefish]

OP: Nice.

Here's another one.