MicroTrainer Relay Basic Electrical Training System

The MicroTrainer Relay Card is a compact, hands-on training tool designed to help students understand how electromagnetic relays work in DC circuits. Perfect for classroom or lab environments, it introduces the foundational principles of relay operation, coil energization, and switched circuit control through real-world, measurable examples.

Each unit includes a populated PCB with relay components, a 9V battery holder and a 3D-printed protective base. A 9V battery is not included.

Try it before you buy it. A free browser-based simulator of this exact card: both relays running, the coil and contact readings a multimeter would show, and where to put your leads for each one. No sign up, nothing to install, and it downloads as a single file for classrooms with no internet. Open the relay simulator.

Interactive Relay Operation Simulator

A free browser-based demo that mirrors this board. Energize either relay and watch the armature pull in, the contacts change over, and every meter reading move with it.

• Both relays on the card — the 4-pin SPST and the 5-pin SPDT, including how 87a hands off to 87
• See where the leads go for every reading: coil voltage across 86–85, coil current, coil resistance, and B+ at pins 30, 87 and 87a
• Work the card’s own diagnostic tree: no click faults on the control side, click-but-no-work faults on the load side
• Watch a weak 9V battery sag below the relay’s 7.2 V pick-up voltage — current flowing, nothing moving
• Switch the coil off with and without the flyback diode and see the back-EMF spike a meter can never show you

▶ Open the Relay Operation Simulator in your browser

How to use offline: Use the download button on that page to save the demo as a single HTML file. Double-click it to open in any browser — no internet needed.

For purchase orders, international shipping, or larger quantities, please contact scott@sbctrainingllc.com