[[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]] (UJT), except that itits behavior can be controlled using external components. In a UJT, the base region is divided into two parts by the emitter. The two parts of the base form a [[programvoltage (computer)|programmabledivider]]{{explain|date=March, 2019}}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|date=15 December 2017|url-status=dead|archive-url=https://web.archive.org/web/20180105205818/https://www.daenotes.com/electronics/industrial-electronics/put-programmable-unijunction-transistor|archive-date=2018-01-05}}</ref>
==Construction==
In construction, Programmablethe unijunctionprogrammable transistor is similar to the [[Siliconsilicon controlled rectifier]] (SCR). ItLike SCR, it consists of four layers,two‒ pPNPN ‒ but its gate is connected to the second layer (N-type), layersnot andthe twothird none (P-type) layers inas equalwith proportionSCR.<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"/>
