What battery?

[(*steve*)]

I have an old battery operated device (for the curious its a Lafayette 7601S G.S.R.) and I am trying to identify the batteries it requires.

It contains what is most likely an op-amp withe the two batteries centre tapped to form a double ended power supply.

The batteries are cylindrical and a little longer and probably thicker than an AA cell. I can only tell this from the battery holders.

BTW, the DIL chip has no visible labelling and gold plated legs. If I had to guess I'd say it was maybe a 709??? That would suggest a battery voltage of between 9V and 15V, but Id like to confirm there was a battery of these dimensions and with what voltage.

 

[(*steve*)]

Hmmm, the E126 8.4V mercury battery sounds like it could be it.

 

[73's de Edd]

.

Sir Steve . . . . . .



When I saw your Lafayette I was initially keying in on olde tyme Lafayette Radio, but with your dealing with GSR . . .Galvanic Skin Response / Resistance.
This device must be of Lafayette Instruments . . . . . . . . polygraph fame.

Are there any code dates on parts, to be able to hone in even closer on its vintage and any electrolytics to be able to see the max voltage level expected.
In the 60's ----- 70's premium DIP's in CERAMIC housing, and gold flashed pins just went along with the packaging on Mil- Aerospace and High end consumer / instrumentation utilization.
Goldplated sockets also, if they were utilized.

If that was back just to the infancy of I.C.s that could have even used hearing aid batteries, they made some 15 volters at the dia sizing and length of an AA but the sides of the cells were squared up.

Close up photos wouldn't hurt either.

Plus you can key in on the power supply being routed to 7 for the + and 4 for the negative and the output at 7 ending up as the output, be it analog metering or chart recorder ?
Funny how those numbers are right on top of my head after all of the years . . . . just like knowing the pin numbers to elements of popular used vacuum tubes.



73's de Edd


.

 

[73's de Edd]

Also . . .go back in time and find all of the most popular ones, used in that era.

http://www.alliedcatalogs.com/catalogs/1965-650/

73's de Edd

 

[(*steve*)]

Apologies for the lack of cropping in these images.

The battery shown is a AA cell. It clips in fairly tightly into the holder and their curvature suggests the designed battery diameter is a little smaller. Clearly the correct battery is also about 3mm longer.

 

[73's de Edd]

.


Sir Steve . . . . .


AaaaaaHaaaaa . .. with your forthcoming reference . . .looks like circa 66-67 vintage instrumentation.

The pin assignment of the Eye See, as being related to board connectivity is not condicive of this unit being a ua709, but its
forerunner a ua 702 from Fairchilds stable of early day op amp offerings.

Its sort of an odd duck in its power supply spec of a normal +12 VDC . . . . . . .but using . . . .- 6 VDC on its other supply rail.

Probably a 50-0-50 ua meter movement, if being a Triplett or Simpson you should be able to peer inside and then DOWN to the bottom
of its frontal meter plate and see the sensitivity in vewy-vewy fine lettering.

If that is a AA in the holder, looks like it needsto put on some weight to fill out and fit within that Keystone holder, and also, grow a bit in length .
I really think that unit was using two looooooooooooog life mercury cells in those holder and s being akin to the sizing of the E126 series
of batts.

Maybe a pair of the equivalency of the 1N914 diodes are being used for the back-to-back meter clamping diodes, every manufacturer
seemed to have their favorites and used only those numbers across the board in their designs.

The now- a- days 1N4148 "standard" diode was antedated by the 1N914 and before that, I saw a bunch of 1N645's used.

Being dual battery powered, they switched both legs via the DPST switch, one control pot to set the gain and another pot used to keep
the average reading at or near zero center . . . . . much like setting the centerline on a chart recorder on their polygraph equipment..

Looks like they used two quality tantalum electrolytics for two out of the three.

Both controls, and particularly the balance control, probably need cleanings, and then, for sure, a coverup of the hole left for an accessory switch .


73's de Edd


.

 

[(*steve*)]

Thanks for the pointers. I shall look up the UA702 and learn of it's wonders