Digital Test
Honeywell / Schneider Digitest 500

Manufacturer: Honeywell / Schneider
Model: Digitest 500
Year: 1969
Schematic: RE
Functions: DCV, ACV, Ohms
Display: NIXIE
Digits: 3
Logic: discrete transistor, LSI

A funny little VOM built into a calculator-style case. The matrix organisation for the function/range selection is novel.

This is actually a Schneider product made in France, re-badged for sale under the Honeywell name. The model was also sold under the Schneider name. The Schneider units seem to be more prevalent, at least in Europe, based on web searches.

A single IC contains most of the digital portion of the electronics - the counters and display multiplexing circuitry - a fairly high level of integration for the time. A single 709 op-amp is also present, the rest of the circuitry is discrete, albeit with several special multiple-resistor ceramic modules.

The unit can be operated from both the AC mains or an external 12 VDC supply (tip negative on the DC barrel connector). The AC mains supply can be configured for 100 to 240VAC, the selection being made by solder connections on the bottom of the main circuit board.

- Unit Log -

Serial Number: 10972
Year of Manufacture: 1969 (Component date stamps)
Date of Receipt: ~ 1998
State upon Receipt: Grubby, some scratches. Missing power cord with oddball connector.

Date: ~ 1998
Procedure: Cleaned. Power cord mocked-up for use. Functional.

Date: 2005 Mar
Procedure: Seems to have intermittent problem on resistance ranges.

Date: 2011 Sep
Procedure: Reverse engineered to produce schematic.

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Early Digital Test Equipment