The UY1N is a half wave rectifier designed to operate in domestic equipment without a mains transformer. The 100 mA heater is designed for heater chain use directly across the mains with a ballast resistor to drop and excess voltage.
The UY1N can supply up to 140 mA of output current and is rated to work with a large maximum reservoir capacitor of 50μF.
End on the anode can be seen to consist of two plates pressed together with a small central cylindrical hole for the cathode to sit in.
The wide glass tube envelope is 30 mm in diameter, and excluding the IO base pins is 79 mm tall.
References: Datasheet, 3002 & 1040. Type UY1N was first introduced in 1941.
Absolute Maximum Operating Conditions¶
Updated February 07, 2013.