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Industrial panel meters made the transition from analog to digital in the early 1970's. This is one of the few NIXIE-display models produced before such instruments settled in to the use of LEDs for display.
The A-to-D converter is of the dual-slope integration type, implemented with discrete and SSI components. The design impressively achieves this with a relative paucity of components, and packed into a small form factor.
The native range of the design is +/- 200.0 mV, auto-polarity is included.
Model options allowed for internal input configurations for other voltage and current ranges.
Overflow is indicated by a flashing of the display.
Bottom of case showing model options.
Analog / upper board with power supply and input amplifier.
Digital / lower board with integrator, counter and display.
| Serial Number: | 73902 |
| Year of Manufacture: | 1970 (IC date stamps of 7011 to 7039). |
| Date of Receipt: | 2006 |
| State upon Receipt: | OK physically, a little shaky functionally. |
| Date: | 2006 Mar |
| Procedure: | Cleaned. RE'd. |
| Date: | 2006 Mar 27 |
| Symptoms: | Socket pin for DP of LSD will not accept tube pin. |
| Procedure: | Socket pin removed. A couple of other pins have intermittent contact. |
| Date: | 2008 Mar 07 |
| Symptoms: | Display does not light up. |
| Procedure: | Anode supply not present. Secondary of transformer is open. Break in fine wire of secondary found on top of windings near where it connects to more-solid lead. Managed to scrape enamel off and get a lead extension to solder to it. Resistance now measures around 2.2 or 3.3 K. |
| Date: | 2015 Nov |
| Procedure: | Design analysed, noted to be dual-slope integration. |
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.. | Weston 1294 | ..
Early Digital Test Equipment |
bhilpert |