Uploaded December 2024 | Updated September 2026, 1 week ago

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In this video, I describe the HeathBuilt EUW-16(A) Voltage Reference Source, which is one of about 15 special 'factory built" pieces of laboratory and test equipment that the Heath company produced specifically for the college/university/technical school market, including the "Malmstadt-Enke Instrumentation Lab" set and the "Berkeley Physics Lab" set in the late 1960s and early 1970s.

This product is dual-regulated voltage SOURCE (NOT a power supply....it cannot deliver any appreciable power to a load) with a precision voltage divider that lets the user control the output voltage from 0.1mV up to 100V. It can also be used in sum & difference mode, comparing or adding the internally generated voltage with an externally applied DC voltage.

Here, I talk about the product's history, its place in the overall HeathBuilt series, and I demonstrate it in operation. I also show the restoration steps I took and I show a small 'hack' that I made to make it easier to adjust the voltage regulator tube and Zener diode currents.

Timeline Table of Contents:
- 00:00 History
- 09:28 Introduction & Overview
- 16:10 Restoration
- 30:47 Hack
- 32:33 Initial test
- 36:00 Calibration
- 40:42 Demonstration
- 54:19 Final assembly and cleanup
- 54:58 Beauty shot
- 55:11 Manual overview
- 1:02:50 Schematic diagram & theory of circuit operation