How to Make Electric Stimulators

The demonstration of muscle contraction in a dissected frog is one of the most common high school lab experiments.

The wonders and complexities of animal anatomy can be difficult to convey with just illustrations, overhead projections and PowerPoint demonstrations. This is why experiments are such a prominent part of biology classes and science fairs. One useful tool for conducting experiments in biology is an electric stimulator -- used to cause muscle contractions in frogs and other dissected lab animals. It demonstrates the bioelectrical nature of muscle control. While you can purchase this type of device, you can make one yourself for less.

Things You'll Need

• Craft knife
• 2-foot length of standard two-prong electrical cord
• Wire stripper
• Test leads
• 9-volt alkaline battery
• 9-volt snap leads
• Electrical tape

Instructions

1. Use a craft knife to divide two ends of a length of electrical cord. Use a wire stripper to remove 1/2 inch of the plastic around the metal wires, to get four exposed ends.

2. Cut the snaps off the test leads, and remove 1/2 inch of the plastic around the metal wires.

3. Wind one of the four exposed ends of the electrical cord around one of the exposed lead wires, and twist them together. Wrap this connection with electrical tape. Repeat this with the other exposed electrical cord at the same end of the wire and the other lead wire.

4. Twist the other ends of the electrical cord onto 9-volt snap connectors. Wrap these connections with electrical tape.

5. Snap the ends of the connectors onto the 9-volt battery.

Tips & Warnings

• Use this device only on dead lab subjects. It should not be used on living people or animals.

• Do not lay the two ends of the test leads down so that they touch each other, since this will drain the battery.

References

• Wofford College: Lab Set-ups for Physiology
• State University of Campinas: The Discovery of Bioelectricity