BC108 Transistor Family

The BC108 Family: Workhorse Transistors with Unexpected Flair

The BC107, BC108, and BC109 transistors, collectively known as the BC108 family, are legendary in the world of electronics. These low-power silicon NPN bipolar junction transistors (BJTs) were the go-to choice for countless circuits and devices from the 1960s onwards, particularly in Europe, Australia, and beyond.

Born in 1963 and formally introduced in 1966 by Philips and Mullard, these tiny titans initially came in metal TO-18 packages. But their reach extended far beyond their humble beginnings. Over time, the family expanded to include:

• Other package types: Plastic options like the TO-92 made them even more versatile.

• Higher voltage ratings: From the standard 25V to beefier options for demanding applications.

• A wider range of gain (hFE): Different versions catered to specific needs for current amplification.

• Complementary PNP types: The BC187, BC188, and BC189 joined the party for balanced circuits.

But what truly set the BC108 family apart was their unassuming reliability and ease of use. They were the perfect foot soldiers for a vast array of electronic projects, from the mundane to the marvellous.

Beyond the Ordinary: Unusual Applications of the BC108

While the BC108 family thrived in bread-and-butter applications like audio amplifiers, radio circuits, and simple logic gates, their versatility shone through in some rather unexpected places:

• Early homebrew computers: The legendary KIM-1 single-board computer, released in 1975, relied heavily on the BC108 for its logic and clock circuits.

• Musical instruments: These humble transistors found their way into iconic effects pedals like the Vox Tone Bender and the Shin-Ei FY-2 Fuzz. Their subtle clipping characteristics added a touch of vintage grit to guitar tones.

• Espionage: Believe it or not, the BC108 family played a role in Cold War spy gadgets. Their small size and low power consumption made them ideal for covert listening devices and transmitters.

• Art and robotics: Even the world of art and robotics couldn't resist the BC108's charm. They were used in kinetic sculptures, interactive installations, and even early robots for basic control functions.

A Legacy that Endures

While newer, flashier transistors may have taken the spotlight, the BC108 family remains a cherished part of electronics history. Their enduring legacy is a testament to their simplicity, reliability, and surprising adaptability.

So, the next time you come across a dusty circuit board or an old schematic, remember the unassuming BC108. These tiny workhorses might just hold the key to unlocking a forgotten era of electronic ingenuity.