Lecture Multimeter

This meter is designed ONLY for low-voltage DC circuits (batteries, signal generators). DO NOT connect to mains voltage (120V AC) - this will damage the instrument and melt the leads. The common terminal is grounded to the chassis. Maximum safe voltage is approximately 40V DC.

Use only touch-safe voltages (generally under 50V DC) to ensure student safety during demonstrations. When demonstrating with batteries, use common sizes (AA, C, D, 9V) that students can safely handle if invited to participate.

Purpose

A large-format LED multimeter (3W Demo Multimeter U21100) displays voltage, current, and resistance in 2-inch digits visible across a lecture hall. Front and rear displays let the instructor read measurements without blocking students' view.

Front panel of 3W Demo Multimeter U21100 with large red LED display reading 1.517 V; hand holds a battery against the test leads

Rear of demo multimeter showing LED display reading 2.020, four DB-9 serial ports, RS232 interface, power cord, and fuse holders

Figure 1: Front panel showing the 2-inch LED display reading 1.517 V while measuring a battery. Controls select voltage, current, resistance, temperature, and pH modes.

Figure 2: Rear display reads 2.020, allowing the instructor to monitor readings while facing the class. DB-9 ports provide RS232 interface and connections for remote displays.

Lecture Multimeter

1

Danger: Voltage Limitation - Critical

Warning: Touch-Safe Voltages Only

Purpose

Safety Warnings

Danger: Voltage Limitation - Critical

Warning: Touch-Safe Voltages Only

Purpose