Ohm’s Law

Equipment: Low voltage DC Powers supply available at every station. Circuit boards, multimeters, 5 ban-ban wires, resistor packs, and jumper wires should be stacked on cart or table in front of room.

Set up

Hook up one multimeter, the power supply, and circuit board as displayed below.

Next we need to make sure the voltage and current knobs are all the way down on the power supplies and that the multimeter is set to 200mA DC to start. Then we will set up our circuit, and have the instructor check everything before we turn anything on.

*note* some stations have a different power supply, which can be seen in the 2nd image on this page. Some classes will use a different circuit board which can be seen in the 3rd image below. And the lab uses a variety of different multimeters (alternates not pictured) so we need to make sure we plug the first one in properly with the positive going to the mA port and com going out to the red (“+”) terminal of the board.


Board connections: The board pictured above has built in connections visible by the silver lines on the board. If we look at the red box in the image we see a plug and 2 springs connected by a silver line, therefore we know that if we connect to that plug the associated springs will also be connected.

The board pictured below has less visible connections. If we look at the center we see 2 columns, one boxed in red and one in blue. Each column is one connection so if put our positive wire into anything in the red column, then anything else plugged into the red column will be connected to our positive supply. Everything outside is grouped in rows of 5 boxes. See the green rectangle with 5 holes, all things pluged into any of those 5 will be connected.

Multimeter: After we have the circuit set up we will set up the Voltage meter by plugging a black and a red ban-ban wire into the multimeter in the appropriate port for testing voltage. we then set the multimeter to 20 volts DC.

**Keep in mind that the location of the proper port and position of the dial will vary from the image below with type of multimeter, but the symbols should remain similar

After finishing setting up everything ask your instructor to verify your setup before powering on the power supply.

***It may be necessary to adjust the settings on the Amp meter down from 200mA to get a more accurate reading, but we need to start at the highest to help prevent blowing and fuse or frying the multimeter as we adjust our circuit.