Oltronix LS 7DS Stabilized Rectifier Stabiliserad Likriktare 0-500V 0-240V DC

Oltronix LS 7DS Stabilized Rectifier Stabiliserad Likriktare 0-500V 0-240V DC

The Oltronix LS 7DS is a vintage Swedish-made stabilized DC rectifier (Stabiliserad Likriktare) manufactured by Oltronix Stockholm. It is a tube-based, multi-range variable DC power supply providing selectable voltage and current output ranges, with a built-in analog V/mA panel meter for monitoring output. The front panel is labeled entirely in Swedish and features a well-equipped set of controls and output terminals covering low-voltage heater rails through high-voltage DC outputs up to 500V.

Specifications & What's Included

• Manufacturer: Oltronix, Stockholm, Sweden
• Model: TYP LS 7DS (Stabiliserad Likriktare)
• Technology: Vacuum tube (valve) — tube complement includes UF80, UF80, UL84, UL84 (visible in photos)
• Output voltage range 1: 0–500 V DC
• Output voltage range 2: 0–240 V DC
• Current range: 20–200 mA (variable); 150 mA fixed output terminal
• Heater output: 6.3 V / 4.5 A
• Additional current outputs: 1.5 A and 4.5 A terminal groups
• High-voltage output: 150 V / 30 mA terminal group
• Instrument range selector (INSTR.OMK.): 250 mA, 500 V, 250 V positions
• Panel meter: Analog dual-scale V / mA, 0–250 range
• Controls: FININST (fine adjustment knob), LIKSP. TILL (stabilizer on/off toggle), 240–500V / 0–240V range toggle, 0–500V range rotary knob
• Output connections: Multiple banana-jack output groups across front panel, labeled by voltage/current range
• Mains transformer: Present and visually intact inside chassis
• Form factor: Benchtop, open-frame chassis with side-removable panels
• Country of manufacture: Sweden
• Power cord/plug: NOT included — requires a special power cord or plug (not a standard connector)
• Condition: Sold as-is, untested

Applications

The Oltronix LS 7DS is a mid-20th-century Swedish laboratory DC power supply of the type commonly used in university, government, and industrial research labs throughout Scandinavia and Europe from the 1950s through the 1970s. Tube-based stabilized rectifiers like this one were standard bench instruments for powering electronic circuits and components during development, testing, and calibration work — providing regulated DC at selectable voltage and current levels from a single unit. The multiple output rails (including low-voltage heater supplies at 6.3V and higher-voltage DC rails up to 500V) made them especially useful for powering and testing vacuum tube circuits and equipment — the dominant technology of the era. Today, units like this are of interest to vintage electronics enthusiasts, tube audio restorers, collectors of Scandinavian scientific instruments, and technicians maintaining legacy valve-based equipment. The Oltronix name is associated with Swedish precision instrument manufacturing and is relatively uncommon outside of Europe, making this a rare find on the surplus market.