Reed Sensors in In-road Warning Lights
Road traffic control devices or In-road Warning Lights, are markers, signs and signal devices used to inform, guide and control traffic. These are usually made of reflective materials to provide maximum visibility at nights. Some of these Warning lights also have an inbuilt battery and blinkers for use in roads and highways at important junctions or to indicate other traffic warnings.
For the warning lights that contain batteries, it is important that the blinking circuit be enabled only after installation on roads, to ensure maximum battery life. But, due to the harsh conditions that these in-road warning lights undergo, the battery is sealed off from the environment, within the casing and adding the battery before installation is not possible.
To enable the battery circuit only after installation, Normally closed biased Reed Sensors are built into the casing. In packed condition, these in-road warning lights are de-activate with a low cost external magnet. Before installation on roads, the circuit deactivating magnet is removed and discarded, which then enables the battery circuit and starts the blinkers. Here, biased Reed Sensors are used as power saving devices.
Applications are classified as Position Sensing, Pulse Counting, Electromagnetic or Relay, Temperature Sensing or Magnet Biasing types. This In-road Warning light application is classified as follows and the link gives more information on best practices to help select the most suitable AT band and matching magnet.
The Reed Switches and Sensors used in such applications need to be robust, durable and efficient in meeting a high life expectancy. Our engineers work hard in life testing our products under various conditions, and our intention is to ensure end product durability and life. Although we wouldn’t want to restrict any of our products for use in only certain applications, the recommended products for use in In-road Warning Lights are listed below.
R5B Ultra-miniature Normally Closed SMD Reed Sensor
|Polarity Sensitive, Normally Closed (NC), 6.5mm body length. 5W switching capability at 0.35 A...Continue reading|