Description
Bausch & Lomb 31-35-28 Microscope Illuminator Transformer 4 5.4 6.5V AC 120V
The Bausch & Lomb 31-35-28 is a benchtop transformer designed to power the lamp illuminators used on Bausch & Lomb stereo and compound microscopes. It steps down a standard 120V AC line to low-voltage AC output — selectable across three brightness levels — to drive the microscope's lamp at the correct voltage and current for consistent, controllable illumination. The lamp plug output connector on this unit has been modified; please refer to the photos for the current connector configuration before purchasing.
Specifications & What's Included
- Manufacturer: Bausch & Lomb
- Catalog Number: 31-35-28
- Type: Microscope Illuminator Transformer / Lamp Power Supply
- Primary Input: 120V AC, 50/60 Hz, 25 Watts
- Secondary Output Range: 3.9–6.6 Volts AC
- Output at Position 1 (low): ~4V
- Output at Position 2 (mid): ~5.4V
- Output at Position 3 (high): ~6.5V
- Rated Output: 6.4V at 3.33 Amps; 6.6V at 1.67 Amps
- Control: Front-panel rotary switch — Off, 1, 2, 3 (three brightness levels)
- Output Connector: Modified lamp plug (see photos)
- Power Cord: Standard 2-prong AC plug
- Certification: UL Listed (File 3858)
- Country of Manufacture: United States
- Compatible Illuminators (per rating plate): 31-32-42, 31-33-33, 31-33-34, 31-33-35, 31-33-04, 31-33-60, 31-34-28, 31-33-39
Applications
Bausch & Lomb produced a wide range of stereo and compound microscopes throughout the mid-to-late twentieth century, and this transformer is the dedicated power supply for the external illuminator accessories used with those instruments. The 31-35-28 provides the low-voltage AC required by incandescent microscope lamps, with the variable output allowing the user to adjust lamp brightness to suit the specimen and magnification. These transformers are commonly sought by labs, educational institutions, and collectors maintaining vintage Bausch & Lomb microscope systems — particularly the stereo microscope lines from the 1960s through 1980s that used the compatible illuminator models listed above. Because many Bausch & Lomb stereo microscopes from this era remain in service in teaching labs and biological research settings, replacement and spare illuminator transformers like this one continue to be in demand.
This Bausch & Lomb 31-35-28 Microscope Illuminator Transformer has been tested and is in working order. The lamp plug output has been modified — please refer to the photos for details on the current connector configuration before purchasing. The unit shows normal wear consistent with lab use, including light surface marks on the housing. The rotary brightness switch and power cord are intact and functional. Please note: We have multiple units in stock — yours may not be the one shown in the photos, however, it will be similar in condition and function.
Warranty Information
Additional Information
Brand: |
Bausch & Lomb |
Model: |
31-35-28 |
MPN: |
31-35-28 |
Type: |
Microscope Illuminator Transformer / Lamp Power Supply |
SKU: |
46513 |
Condition: |
Used – Inspected and Tested |
Primary Voltage: |
120V AC, 50/60 Hz, 25 Watts |
Secondary Voltage: |
3.9–6.6 Volts AC |
Output Settings: |
4V, 5.4V, 6.5V (3-position rotary switch) |
Output Current: |
6.4V at 3.33A; 6.6V at 1.67A |
Power Rating: |
25 Watts |
Frequency: |
50/60 Hz |
Output Connector: |
Modified lamp plug (see photos) |
Control: |
3-position rotary switch (Off, 1, 2, 3) |
Compatible With 1: |
B&L Illuminator 31-32-42 |
Compatible With 2: |
B&L Illuminators 31-33-33, 31-33-34, 31-33-35 |
Compatible With 3: |
B&L Illuminators 31-33-04, 31-33-60, 31-34-28, 31-33-39 |
Certifications: |
UL Listed (3858) |
Country/Region of Manufacture: |
United States |
Form Factor: |
Benchtop |
Power Requirements: |
120V AC, 50/60 Hz |
Seller Notes: |
Lamp plug output has been modified; see photos. Tested and in working order. |
Condition Notes: |
Bausch & Lomb 31-35-28 Microscope Illuminator Transformer. Tested and in working order. Lamp plug output has been modified — see photos. Normal wear on housing. Please view photos and contact us with questions. |
