Description
Build, understand and experiment with one of the most important analogue building blocks.
The Current Sink Mirror Experimentation Board is a compact through-hole PCB designed for learning, prototyping and permanently building simple transistor current sinks.
Using just two matched NPN transistors and a single resistor, the circuit creates a nearly constant current that can be used to bias amplifiers, improve differential amplifiers, drive LEDs, or replace ordinary resistor biasing.
Although the circuit itself is simple, current mirrors form the foundation of countless analogue integrated circuits, including operational amplifiers, voltage regulators, comparators and precision current sources.
This board provides an easy way to explore how they work and how transistor matching influences circuit performance.
Features
- Simple two-transistor NPN current mirror
- Adjustable current set by a single resistor
- Through-hole components only
- Compact and beginner-friendly layout
- Easy to modify and experiment with
- Ideal companion for differential amplifier projects
- Suitable for permanent installations or laboratory experiments
How It Works
One transistor is connected as a diode by joining its collector and base together. A resistor connected to the supply establishes a reference current through this transistor.
Since both transistor bases are connected together, the second transistor receives nearly the same base-emitter voltage.
Assuming the two transistors are reasonably well matched, the second transistor will sink approximately the same current as the reference transistor.
The result is a simple but remarkably effective constant current sink.
What Can You Build?
The board can be used in a wide variety of analogue circuits, including:
- Differential amplifier tail current source
- Constant current LED driver
- Transistor amplifier bias networks
- Active collector loads
- Long-tailed transistor pairs
- Precision current experiments
- Sensor excitation circuits
- Current limiting demonstrations
- Analogue laboratory experiments
Learn About
The board is ideal for studying topics such as:
- Bipolar transistor operation
- Constant current circuits
- Current mirrors
- Current sinks versus current sources
- Transistor matching
- Base-emitter voltage (VBE)
- Collector current
- Early effect
- Compliance voltage
- Temperature dependence
- Analogue IC design principles
Typical Applications
Current mirrors are fundamental building blocks found in many analogue designs, including:
- Operational amplifiers
- Instrumentation amplifiers
- Voltage comparators
- Active filters
- Voltage regulators
- Audio amplifiers
- Analogue integrated circuits
- Precision measurement equipment
Ideal For
- Electronics beginners
- Engineering students
- Universities
- Technical colleges
- Makers
- Electronics hobbyists
- Teachers and educators
