Bausch & Lomb 31-35-47 Microscope Illuminator Transformer 120V 5-6.5V 2.75A

Bausch & Lomb 31-35-47 Microscope Illuminator Transformer 120V 5-6.5V 2.75A

The Bausch & Lomb 31-35-47 is a dedicated step-down transformer and light source controller designed to power the illuminator lamps used on Bausch & Lomb microscopes. It takes standard 120V AC mains power and steps it down to a low-voltage output in the 5.0–6.5V range, providing the controlled current needed to drive a microscope lamp safely. A rotary knob on the front panel adjusts illumination intensity across four positions — Off, 1, 2, and 3 — giving the user direct control over lamp brightness.

Specifications & What's Included

• Catalog No.: 31-35-47
• Primary input: 120V AC, 50/60 Hz, 35W
• Secondary output voltage: 5.0–6.5V
• Output current: 2.75A
• Rated output: 6.5V @ 2.75A
• Front-panel rotary intensity control: Off / 1 / 2 / 3
• Rear 3-pin proprietary output connector for lamp connection
• AC power cord with standard 2-prong plug, attached
• Compact benchtop / freestanding form factor
• Black painted metal housing

Applications

Bausch & Lomb produced a long line of research-grade and educational microscopes through much of the twentieth century, and low-voltage illuminator transformers like the 31-35-47 were standard accessories for their transmitted- and incident-light microscope systems. The transformer steps mains voltage down to the 5–6.5V range required by the small tungsten lamp assemblies fitted to these instruments, protecting the lamp from overvoltage while the rotary control lets the operator tune brightness to the specimen and magnification in use. These units are still sought after by labs and collectors maintaining vintage Bausch & Lomb microscopes, as the proprietary 3-pin output connector and voltage range make the 31-35-47 a direct fit for compatible B&L illuminator assemblies. They are also commonly used as replacement power sources when original illuminators are upgraded or repaired.