J201 transistor


J201 is a JFET N-channel transistor that mostly had applications at general-purpose amplifiers, J201 is a medium power FET device.

The J201 is a low-level audio device and when we made an amplifier circuit using J201, they must be a high impedance source.

J201 JFET features

  • J201 is an N-channel JFET transistor device
  • Maximum drain to gate voltage (VDG) is 40v
  • Maximum gate to source voltage (VGS) is -40v
  • Peak gate current (IG) is 50mA
  • Power dissipation (Pd) is 625mW
  • Junction temperature (TJ) is -55 to 150°C
  • low noise
  • high gain
  • high impedance
  • TO-92 Package

J201 transistor Pinout details

J201 transistor Pinout details
J201 transistor Pinout details
PIN1 Drain
PIN2 Source
PIN3 Gate


The Pinout details of the J201 JFET transistor are started from left to right, drain, source, and then the gate.

And the package used at J201 is TO-92, we know it is a common transistor package and the main specialty of this package is the compactness and less expensive making.

J201 transistor description

J201 JFET transistors had a major portion of applications at amplifier-related circuits, the low noise and high gain property of the transistor makes it suitable for such operations.

The maximum drain to the gate voltage of J201 is 40v and the gate to source voltage is -40v, this voltage value makes this device used for general purpose applications.

The peak gate current of the J201 JEFT transistor is 50mA, this makes the maximum load applied for this device.

Maximum power dissipation at the J201 transistor is 625mW, this particular value will be mostly depended on the device package.

The junction temperature of the J201 transistor is –55 to +150°C.

The low power operation of the J201 transistor makes it also suitable for the surface mount version.

J201 transistor datasheet

J201 transistor datasheet
J201 transistor datasheet


 J201 transistor equivalent

The JFET transistor equivalent for J201 is 2n4338, 2n5459, 2n5457, and J174, this JFET transistor type listed here has an almost similar specification to the J201 transistor.

 The electrical and physical specifications of JFET transistors at the equivalent list are slightly different, so before the replacement of the J201 transistor, we need to check and verify the characteristics.

J201 transistor SMD

J201 transistor SMD
J201 transistor SMD

The J201 transistor had its surface-mount version MMBFJ201 (SOT-23), the J201 is a general-purpose transistor with a low power rating, so making of SMD version using the J201 transistor is an easy process.

J201 preamp circuit diagram

J201 preamp circuit diagram
J201 preamp circuit diagram

 The figure shows the preamp circuit using the J201 JFET transistor, the circuit consists of few components with the signal stage of the preamplifier.

The J201 transistor is a general-purpose amplifier component with low power, so when the signal reaches the JFET, it makes a medium power output.

These preamp circuits have more applications than guitar amplifier circuits, but the advantage of the J201 transistor is it has low noise and high gain at the operation.

J201 transistor uses

  • General-purpose application circuits
  • Sensor circuits
  • Preamplifier circuits
  • Data amplifier circuits
  • Laser detection circuits
  • Buffer circuits
  • Guitar amplifier circuits
  • Voltage booster circuits
  • Low-level audio amplifier circuits

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