2N2646 UJT transistor

2N2646 UJT transistor
2N2646 UJT transistor

2N2646 UJT transistor electrical specification

  • 2N2646 is a general-purpose PN unijunction transistor device
  • Emitter reverse voltage (B2E) is 30V
  • Inter-base voltage (VB2B1) is 35V
  • RMS emitter current (Ie) is 50mA
  • Power dissipation is 300mW
  • Junction temperature is between -65 to 150℃
  • Emitter saturation voltage (VEBI (SAT)) is 5V
  • Inter-base resistance (RBB) is 7 to 9.1kΩ
  • High reliability
  • Low emitter reverse current
  • Low peak point current
  • Passivated surface for reliability & uniformity
  • Low saturation voltage

2N2646 UJT transistor Pinout

2N2646 UJT transistor Pinout
2N2646 UJT transistor Pinout
Pin Number Pin Name Description
1 BASE 1 Connected to power source
2 EMITTER The emitter terminal is used to trigger the device
3 BASE 2 Connected to load
4 CASE The case is been connected with base2 internally


2N2646 UJT transistor package

The device package used at the 2N2646 transistor is TO-18, it is a general-purpose power transistor package.

TO-18 package is made with metal, this is why these transistors had higher temperature capacity and compactness.

The 2N2646 UJT transistors are general-purpose devices mainly used for small circuit applications, this TO-18 package is apt as a compact electronic component. 

2N2646 UJT transistor electrical specification description

In this section, we try to explain the electrical specifications of the 2N2646 UJT transistor device.

Voltage specs

The terminal voltage specs of the 2N2646 transistor are emitter reverse voltage is 30V, inter-base voltage is 35V.

The emitter saturation voltage is 2.5V

The voltage specifications of 2N2646 UJT show, that it is a general-purpose transistor device.

Current specs

The RMS emitter current is 50mA, it is the current for triggering the 2N2646 UJT transistor.

Dissipation specs

The power dissipation of the 2N2646 UJT transistor is 300mW, the dissipation capability will mainly depend on the device package.

Junction temperature

 The junction temperature of -65 to 150℃, which is a general-purpose transistor temperature value of capacity.

Inter-base resistance

The inter-base resistance is the overall resistance of the 2N2646 UJT transistor, it is between 4.7 to 9.1kΩ.

2N2646 UJT transistor DATASHEET

If you need the datasheet in pdf please click this link

2N2646 UJT transistor equivalent

The transistor devices such as 2N2647, 2N4871, 2N4870, and 2N1671 are the equivalent UJT transistors of 2N2646.

Most of the electrical specifications of these transistors are the same as the 2N2646 device, so we can easily replace them at circuits.

2N2646 vs 2N4871

In the table below we list the electrical specifications of 2N2646 vs 2N4871 UJT transistor.

Emitter reverse voltage (V­B2E)     30V30V
Inter-base voltage (VB2B1)35V35V
RMS emitter current (Ie)50mA50mA
Emitter saturation voltage (VEBI (SAT))2.5V2.5V
Power dissipation300mW300mW
Junction temperature (TJ)-65 to +150°C-55 to +150°C
Inter-base resistance (RBB)4.7 to 9.1kΩ4 to 9.1kΩ

The 2N2646 and 2N4871 transistors had the same electrical and physical characteristics.

2N2646 UJT transistor applications

  • General-purpose industrial applications
  • Tuner circuits
  • Sensing circuits
  • Trigger circuits
  • SCR firing circuits
  • DIY making
  • Phase control circuits
  • Used at SAW tooth wave generator circuit
  • Voltage detector
  • Hobby circuits

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