Monday, December 7, 2015

Precision Resistors - UNS 4-T220 - Riedon

These Precision Shunt Resistors are designed for systems which have a fast changing electrical load. It has a Heatsink and is encapsulated in epoxy. The substrate is Alumina for Good Heat Transfer but with Electrical Insulation. It is a Resistor formed by a NiCr Foil. (Like Nichrome).

Precision Resistors - UNS 4-T220 - Riedon

 Precision Resistors - UNS 4-T220 - Riedon
Specifications
  • Resistance from 0.2 Ohm to 80 Ohms
  • Power Rating to 15 Watts
  • Resistance Tolerances to ±0.01%
  • TCR to ±1ppm/K
  • Load Stability to 0.01%
Here are some documents that will build your awareness on how Resistors work and their Thermal behavior. These are from a firm called Riedon who design manufacture custom resistors and special resistors used in tight design requirements.

Resistors are probably the most common and well known of all electrical components. Applying a resistor to a circuit normally requires (1) calculating the nominal values needed in the circuit application (resistance, power rating, etc.) then (2) developing acceptable tolerances for the resistor that ensure it will function properly in all extremes of the application.

Read up the "Temperature dependence and TC" - The absolute ohmic value of a resistor is temperature-dependent. Also the "Definition of terms in the specifications of Resistors."

Riedon Inc
300 Cypress Avenue Alhambra, CA 91801, USA

Saturday, December 5, 2015

Digital Potentiometer - AD5242 - Analog Devices

AD5241 and AD5242 provide a single-/dual-channel, 256-position, digitally controlled variable resistor (VR) device. They have 2-Wire I2C Compatible Digital Interface.

Digital Potentiometer - AD5242 - Analog Devices

They are Analog Semiconductor Replacements for Electromechanical Devices like potentiometer, trimmer or variable resistor.

The Advantage of the latter is low cost and easy to configure and use. The Advantage of the Digital Version is "No moving Parts". hence not limited to things like "10000 operations". Another clear advantage is precision and vibration resistant.

See an Application of this Digipot in a TinyOS hardware magnetometer.. 

Digital Potentiometer AD5242 Magnetometer Application

The temperature stability of 30 ppm/°C and low noise settings is also achieved with SiCr thin film resistor technology. They range from 10K, 100K and 1M Ω End-to-End Terminal Resistances.

Digipots are not for high currents or power, even high voltage and very low resistance values are not for these devices. These are signal control devices. Use it for analog circuits and instrumentation and signal control too.

Tuesday, December 1, 2015

Web Enabled 4-20 mA Input Controller

RST-5000 module has been developed to provide a cost-effective solution for the monitoring of local and remote tanks or processes. It can accept any 4-20 mA output from a sensor and provide a method of calculating and reporting the level or volume of a vessel. It can also be set up to display and record user-defined units such as PSI, Temp, PH, etc. Readings are reported to a secure database on the Internet via an existing network connection.

Web Enabled 4-20 mA Input Controller
Programmed via internal web page; no special programming software required. Two programmable solid-state relays (130 mA max.) for process control or alarm points

Web Enabled 4-20 mA Input Controller

Some Features
  • Compatible with any 4-20 mA device
  • Employs Power Over Ethernet (POE)
  • 24 VDC power for sensor
  • Can use standard 24 VDC supply
  • Din-rail mounting
Automation Product Group, Inc.
1025 W 1700 N Logan, Utah 84321-1713 USA