Power Transistor BD677 NPN Darlington, 4A TO-126

Power Transistor BD677 NPN Darlington, 4A TO-126

Transistors

Reference: TRBD677

Part.No: BD677

€1.20

Last items in stock

Immediate Dispatch

The BD677 is a high-gain NPN Darlington transistor in a TO-126 package. Engineered for switching and driving high-current loads—relays, solenoids, and small motors—with minimal base current.

Add to cart

Subscribe To When In Stock

You have successfully subscribed to this product

Description
Product Details

BD677 Darlington Transistor — High-Gain Power Switch for Relays & Motors

The BD677 is a robust NPN Darlington transistor, combining two transistor stages internally to deliver exceptional current gain. With its TO-126 package and moderate power dissipation, it is ideal for applications requiring reliable switching of medium-current loads from low-impedance sources like microcontroller outputs or sensor circuits.

Functions & Applications

Exceptional Current Gain: Darlington configuration delivers gain over 1000, triggering large loads with minimal base current.
Medium Power Handling: 4A collector current rated for relays, solenoids and small DC motors.
Compact TO-126 Package: Flat, space-efficient design with center mounting hole for optional heatsink attachment.
Logic-Level Compatible: Direct drive from 5V and 3.3V microcontroller outputs (Arduino, ESP32, PIC).

Technical Specifications

Parameter	Value / Specification
Transistor Type	Darlington
Polarity / Channel	NPN
Package / Case	TO-126
Collector-Emitter Voltage (Vceo)	80V
Max Collector Current (Ic)	4A
Power Dissipation (Pd)	12.5W
Darlington Configuration	Integrated dual stage
Mounting Type	Through-Hole (THT) with heatsink hole

Frequently Asked Questions

Q: Can the BD677 control a 12V relay coil?
A: Yes, provided the relay coil draws less than 4A. Always protect the transistor with a flyback diode across the relay coil to suppress inductive spikes.

Q: Does the BD677 require a heatsink?
A: For continuous operation above 2A or at elevated ambient temperatures, a small heatsink is recommended. The TO-126 center hole accepts a screw-mounted mica-insulated pad.

Notes

TO-126 case is not isolated on the back; if using a heatsink, insulate with a mica pad to prevent shorting the collector.

Note: Price refers to one (1) piece. The component is shipped in bulk without individual packaging.

Transistor Type: Darlington
Transistor Polarity / Channel: NPN
Transistor Case Style: TO-126

16 other products in the same category:

Transistor 2N3819

Transistors

Transistor 2N3819 N-Channel, 0.1A TO-92

Reference:

TR2N3819

The 2N3819 is a general-purpose N-Channel JFET (Junction Field Effect Transistor) in a TO-92 package. Designed for VHF/UHF RF amplification, mixing and low-noise analog switching in hobbyist and audio circuits.

In Stock

Transistor BC213 PNP, 30V, 0.2A, TO-92

Transistors

Transistor BC213 PNP, 0.2A TO-92

Reference:

TRBC213

The BC213 is a general-purpose PNP Bipolar Junction Transistor (BJT) in a TO-92 package, rated for 30V / 0.2A. Suitable for small-signal amplification and low-power switching in classic and hobbyist circuits.

Last items in stock

Transistor AC116K PNP Germanium

Transistors

Transistor AC116K PNP Germanium

Reference:

TRAC116K

The AC116K is a PNP Germanium audio frequency transistor. The "K" suffix denotes its built-in metal heatsink block.

Last items in stock

Transistor 2SC9015

Transistors

Transistor 2SC9015 PNP, 150mA TO-92

Reference:

TR2SC9015

The 2SC9015 is an epitaxial planar PNP small-signal transistor (BJT) in a TO-92 package, made by KEC. Designed for general-purpose amplification and low-power switching in audio, signal and analog circuits.

In Stock

Transistor AF117 PNP, TO-7

Transistors

Transistor AF117 PNP, TO-7

Reference:

TRAF117

The AF117 is a PNP germanium transistor in a TO-7 package, originally designed for RF and IF amplification in vintage radios. A sought-after NOS (New Old Stock) part for authentic restoration of 1960s portable receivers and vintage radio enthusiasts.

In Stock

Power Transistor BU208D NPN, 15A TO-3

Transistors

Power Transistor BU208D NPN, 15A TO-3

Reference:

TRBU208D

The BU208D is a high-voltage NPN power transistor in a TO-3 package, designed for Line Output (LOPT) switching in television deflection circuits. The integrated snubber diode and base-emitter resistor make it a complete, ready-to-use solution for demanding high-frequency switching applications.

Last items in stock

Power Transistor 2SD1555 NPN, 5A TO-3PF

Transistors

Power Transistor 2SD1555 NPN, 5A TO-3PF

Reference:

TR2SD1555

The 2SD1555 is a high-voltage NPN Bipolar Junction Transistor (BJT) in a TO-3PF isolated package. Designed specifically for horizontal deflection circuits in CRT displays and high-voltage switching applications, featuring a built-in damper diode for protection.

Last items in stock

Power Transistor 2SK2049 N-Channel, 50A TO-220

Transistors

Power Transistor 2SK2049 N-Channel, 50A TO-220

Reference:

TR2SK2049

The 2SK2049 is a high-current N-Channel Power MOSFET in a TO-220 package, made by Fuji Electric. Designed for motor control, DC-DC converters and general-purpose power amplifier applications requiring low on-resistance and high drain current.

Last items in stock

Power Transistor BD530 PNP, 4A TO-220

Transistors

Power Transistor BD530 PNP, 4A TO-220

Reference:

TRBD530

The BD530 is a PNP power transistor in a TO-220 package, engineered for medium-power switching and amplification. Ideal as the complementary pair to the BD529 NPN transistor in push-pull amplifiers, audio drivers, and high-side load switching applications.

Last items in stock

Transistor BD121 NPN, 60V, 5A, 45W TO-3

Transistor BD121 NPN, 60V, 5A, 45W TO-3 2

Transistors

Power Transistor BD121 NPN, 5A TO-3

Reference:

TRBD121

The BD121 is an NPN Bipolar Junction Transistor (BJT) power transistor in a TO-3 metal package. Designed for medium-power switching and amplification stages such as audio output, motor drivers and voltage regulators.

In Stock

Power Transistor TIP120 Darlington NPN, 5A TO-220

Power Transistor TIP120 Darlington NPN, 5A TO-220 2

Transistors

Power Transistor TIP120 Darlington NPN, 5A TO-220

STMicroelectronics

Reference:

TRTIP120

The TIP120 is a high-current Darlington NPN transistor in TO-220 package, designed for driving loads up to 5A. With exceptional current gain and low saturation voltage, it easily interfaces microcontroller outputs with motors, relays, solenoids and other power devices.

In Stock

Transistor BC302 NPN, 60V, 0.5A, 0.85W TO-39

Transistors

Transistor BC302 NPN, 0.5A TO-39

Reference:

TRBC302

The BC302 is an NPN Bipolar Junction Transistor (BJT) in a metal TO-39 package, rated for 60V and 0.5A. Suitable for general-purpose amplification and switching applications requiring a robust metal-can case.

Last items in stock

Transistor BC231 PNP, 30V, 0.35A, TO-39

Transistors

Transistor BC231 PNP, 0.35A TO-39

Reference:

TRBC231

The BC231 is a PNP Bipolar Junction Transistor (BJT) in a metal TO-39 package, rated for 30V and 0.35A. Suited for small-signal amplification and switching in general-purpose analog circuits.

Last items in stock

Transistor 2SD879 NPN Darlington, TO-92

Transistors

Transistor 2SD879 NPN Darlington, TO-92

Reference:

TR2SD879

The 2SD879 is a high-gain NPN Darlington transistor in a TO-92 package. Engineered for applications requiring massive current amplification, such as relay drivers, motor control, and high-impedance signal switching.

Last items in stock

Power Transistor BU2508A NPN, 8A TO-247

Transistors

Power Transistor BU2508A NPN, 8A TO-247

Reference:

TRBU2508A

The BU2508A is a high-voltage NPN power transistor in a TO-247 package, purpose-built as a Line Output Transistor (LOPT) for CRT monitor and television deflection circuits. It drives the high-voltage flyback transformer in horizontal scanning stages.

Last items in stock

Power Transistor AD149 PNP, TO-3

Transistors

Power Transistor AD149 PNP, TO-3

Reference:

TRAD149

The AD149 is a classic PNP Germanium Power Transistor in a TO-3 package. Designed for high-current amplification and audio power amplifier output stages where reliability and thermal management are critical.

In Stock

Product added to wishlist

Product added to compare.