[[File:UJT caratteristica.png|thumb|Graph of PUT characteristic curve, similar to UJT]]
A '''Programmableprogrammable unijunction transistor''' ('''PUT''') is a three-lead [[Electronics|electronic]] [[semiconductor]] device with which is similar in characteristicits characteristics to a [[unijunction transistor]], except that it is [[program (computer)|programmable]]. In a [[ Unijunctionunijunction transistor]], the base region is divided into two parts by the emitter. The two parts of the base form a [[Voltagevoltage divider]], which sets the operating point of the UJT. That voltage divider can be programmed with two physical resistors connected to the gate terminal of the PUT. This allows the designer some control over the operating point of the PUT.<ref>{{cite web|url=https://www.daenotes.com/electronics/industrial-electronics/put-programmable-unijunction-transistor|title=PUT - Programmable Unijunction Transistor - Working, Construction, Biasing - D&E notes|website=www.daenotes.com}}</ref>
==Construction==
In construction, Programmablethe programmable unijunction transistor is similar to the [[Siliconsilicon controlled rectifier]]. It consists of four layers, two p-type layers and two n-type layers in equal proportion.<ref name="electroschematics.com"/>
==Applications==
* It is used to trigger [[Thyristorthyristor]]s.
* It is also used as a [[Relaxationrelaxation oscillator]].
As of 2012 [[ON Semiconductor]] manufactured a part: 2N6027. 2N6028 was also made in the past.<ref name="electroschematics.com"/>
