The 6E5S is a type of Magic Eye vacuum tube, also known as a "tuning eye" or "cat's eye" tube. Magic Eye tubes were commonly used in the mid-20th century in various electronic devices, particularly radio receivers and audio equipment. They were designed to provide a visual indication of signal strength or tuning accuracy to the user.

The 6E5S is a specific type of Magic Eye tube, and it is part of the 6E5 family of tubes. These tubes typically feature a small phosphorescent indicator screen or target, which is usually shaped like a vertical bar or an elongated eye, and it emits a greenish or bluish glow when activated.

Here are some key characteristics and features of the 6E5S Magic Eye tube:

Indicator Function: The primary function of the 6E5S Magic Eye tube is to provide a visual indication of signal strength or tuning accuracy in radio receivers. When tuning a radio, the user would observe the movement or closure of the phosphorescent bar or eye-shaped target in the tube, which would correspond to the strength of the incoming radio signal.

Visual Display: The indicator display in a 6E5S tube typically consists of a vertical bar that opens and closes, and the width of the bar varies with the strength of the signal. When the signal is weak, the bar is narrow, and when the signal is strong, the bar widens. This provides a visual reference for tuning.

Control Voltage: The operation of the Magic Eye tube is controlled by a specific voltage applied to its control grid. The voltage level determines the degree of deflection of the indicator, which, in turn, reflects the signal strength or tuning accuracy.

Greenish-Blue Glow: The glow emitted by the phosphorescent screen in the 6E5S tube is typically greenish or bluish in color, making it visually appealing.

Vintage Technology: Magic Eye tubes, including the 6E5S, are now considered vintage or obsolete technology. They have been largely replaced by modern digital displays and tuning indicators in contemporary electronics.

Collectible Items: Due to their nostalgic appeal and unique appearance, Magic Eye tubes have become collectible items among electronics enthusiasts and vintage radio enthusiasts.

Keep in mind that Magic Eye tubes like the 6E5S were popular during a specific era of electronics, and their usage has been largely supplanted by more modern technologies. However, they hold a special place in the history of electronics and continue to be of interest to hobbyists and collectors.