OS-260 & OS-270 Resistance Decade Boxes / RTD Simulator

  • The revolutionary ohmSOURCE microprocessor controlled resistor is like nothing you have ever seen before!
  • US Patent 6487456
  • Two cost-effective models available
  • Accuracy's as tight as 0.01%, with resolution as good as 0.01Ω
  • Engineered as an ideal RTD calibrator 
Prices range from $1,165.00 to $1,385.00
Prices range from $1,165.00 to $1,385.00
Estimated Delivery is 1 week

Microprocessor-controlled and loaded with innovative features, the ohmSOURCE Programmable Resistor succeeds in providing highly accurate and precise resistance values in an intuitive and user-friendly fashion. With a resistance value range of up to 24 MΩ and a power rating of up to 1 Watt, the handheld ohmSOURCE decade boxes are practical for all industries including automotive, medical, test and measurement and telecommunications. Translation tables makes the ohmsource an ideal RTD calibrator, there is no need for operators to use conversion tables, just select temperature and the correct resistance is automatically selected.

See the PRS-300 Precision Programmable Resistor for applications requiring improved accuacy and remote control via USB, IEEE or ethernet interfaces.


Keypad Interface Enter resistance values using a calculator-style keypad.

Quick Value Keys: store/recall up to four frequently used resistance values with one touch.

Memory Keys: Store resistance values in up to 10 additional memory locations (0-9).

Translation Tables (Optional Software with USB cable required Part Number OS-91.001) Up to 4 numeric tables allow conversion from your units to a resistance value. Each table holds up to 255 entries; each entry contains your value and an associated resistance value. Your entries represent any type of curve; RTD, thermistor, thermocouple, strain gauge

Current Limiter Limits the amount of current passing through the decade box to prevent possible damage.

Open Key: Electrically isolate the ohmSOURCE connections from the application with the touch of a key.

Increment Value Setting Change resistance by user-defined increments or select standard resistance values (1%, 5%, 10%)

Automatic Eliminates Residual Resistance - the residual resistance is automatically factored out in output resistance value.

Sensor simulation dual display operation being one of the key features, once programmed for your sensor of choice the unit of measure along with the resistance is viewed simultaneously on the display: Platinum Resistive Temperature Devices (RTD, PRTD), Negative temperature coefficient (NTC) Thermistors, Conductivity, Strain gauges, Potentiometric sensors (position, level)

The USB interface on the OS-270 and OS-260 uses an FTDI chip set. Normally when the Ohmsource is connected to a computer using the USB port, Windows 7 and higher will search for the correct driver and as long as the computer is connected to the internet the driver should automatically be installed. If the driver is not automatically installed the drivers can be installed from FTDI Virtual COM Port Drivers website


(See datasheet for full specifications)

≈ 1 Ω to 24  MΩ  
≈ 1 Ω to 1.5 MΩ  
0.1 Ω 
.01 Ω  
Accuracy (no zero subtraction required) 
±0.5 Ω, for 1 kΩ and under ±0.1%, for over 1 kΩ
±0.1 Ω, for 1 kΩ and under ±0.01%, for over 1 k
Power Rating  
1.0 W  
1.0 W  
Power Supply  
4 AAA alkaline batteries  
4 AAA alkaline batteries  
3.3" x 6.6" x 1.25"
Weight: 1.1 lbs
3.3" x 6.6" x 1.25"
Weight: 1.1 lbs