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The B&K Precision 1685B Series is a family of laboratory-grade switching mode DC power supplies designed to deliver high current output in a small, lightweight form factor. The series comprises three models that share a common chassis and control architecture while offering different output configurations: the 1685B (1–60V, 0–5A), the 1687B (1–36V, 0–10A), and the 1688B (1–18V, 0–20A). All three models measure 7.9 x 3.5 x 8.2 inches and weigh 5.2 pounds, making them practical for benches where space and portability matter.
These supplies are positioned for production testing, telecommunications work, R&D benches, electronic field service, and university laboratory environments. The combination of high current output, compact form factor, and remote programming capability suits applications where a controllable DC source is needed but a full-size linear supply would be impractical. Each unit ships with a power cord, instruction manual, application software CD, USB cable, and remote control connector.
B&K Precision was founded in 1951 in Chicago, Illinois, and is currently headquartered in Yorba Linda, California. The company has operated continuously under the B&K Precision name throughout its history.
The 1685B Series consists of three switching mode DC power supplies that share a common chassis, control interface, and feature set while differing in output voltage and current configuration. The 1685B provides the highest voltage at 60V with 5A current capacity, the 1687B occupies a middle position at 36V/10A, and the 1688B delivers the highest current at 20A within an 18V range. Voltage × current works out to 300W for the 1685B, 360W for the 1687B, and 360W for the 1688B.
Across the series, regulation specifications, ripple and noise levels, meter accuracy, switching frequency, transient response, and protection features are identical. The differentiation between the three models is purely in the output range — selection is driven by the voltage and current requirements of the device under test, not by performance tier.
Each model in the 1685B Series is offered on its own product page with new pricing matched to the specific configuration. The links below route to the dedicated page for each model, where current availability, accessories included, and any condition notes specific to that unit are documented.
The most important spec to match when choosing among the three models is the combination of voltage and current the DUT requires. The 1685B reaches 60V but is limited to 5A — appropriate for higher-voltage, lower-current devices. The 1688B reaches only 18V but delivers up to 20A — appropriate for lower-voltage, higher-current devices such as automotive electronics and certain RF amplifier supplies. The 1687B sits between them with a balance of 36V at 10A that suits a wider range of general-purpose bench applications.
Full-load input current also varies slightly with model and line voltage. At 100 VAC, the 1685B draws 3.7A, while both the 1687B and 1688B draw 4.6A. At 230 VAC, the 1685B draws 1.7A and the 1687B/1688B both draw 2.1A. Efficiency at 230 VAC is 86% for the 1685B and 1687B, and 85% for the 1688B.
| Model | Output Voltage | Output Current | Output Power |
|---|---|---|---|
| 1685B | 1 - 60 V | 0 - 5 A | 300 W |
| 1687B | 1 - 36 V | 0 - 10 A | 360 W |
| 1688B | 1 - 18 V | 0 - 20 A | 360 W |
Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.
| Specification | 1685B |
|---|---|
| Variable Output Voltage | 1 – 60 V |
| Variable Output Current | 0 – 5 A |
| Full Load Input Current | 3.7 A (100 VAC) / 1.7 A (230 VAC) |
| Efficiency | 82% (100 VAC) / 86% (230 VAC) |
| Tracking Overvoltage Protections | O/P 1-5 V: set voltage +2 V; O/P 5-20 V: set voltage +3 V; O/P 20-60 V: set voltage +4 V |
Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.
Model No
B&K
Condition
New
Manufacturer
B&K Precision
Current
5 A
Voltage
60 V
Power
300 W
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