Monday, 14 April 2014

protection - Why have a small neon lamp in power supply input circuitry?


A couple of times when taking apart older bits of electronics, I've seen a small neon lamp about the size of a fuse (but its definitely not a fuse) positioned near the power supply circuitry. What is its purpose?


Is it used as some kind of input protection? Does it illuminate under fault conditions? Why not use a MOV or some other purpose designed component?




Answer



It is used as discharger for overvoltage conditions - in case of overvoltage a discharge starts through the lamp and that protects the main circuit from overcurrent.


A neon lamp is used because it is relatively cheap, very reliable and there's zero current through the lamp until the discharge actually starts.


No comments:

Post a Comment

arduino - Can I use TI's cc2541 BLE as micro controller to perform operations/ processing instead of ATmega328P AU to save cost?

I am using arduino pro mini (which contains Atmega328p AU ) along with cc2541(HM-10) to process and transfer data over BLE to smartphone. I...