Electronics Projects: How to Switch between Two Lamps - dummies

Electronics Projects: How to Switch between Two Lamps

By Doug Lowe

There is more than one way to switch the electronic circuit between two lamps or any other electronic power components. This shows two different ways to accomplish the task.

In the first project, you build a simple circuit that uses a single pole, double throw (SPDT) to switch a circuit between one of two lamps, controlling two lamps with one switch. In other words, one of two lamps will light depending on the position of the switch. This type of switching is a common requirement in electronic circuits.


An interesting variant of the circuit in Project 1-7 uses both poles of the DPDT (double pole, double throw) knife switch to switch the circuit on both the negative and positive sides of the lamp. For this circuit, you need four 6″ wires. Connect the six terminals of the DPDT knife switch as follows:

Terminal Connect To
1X Red battery lead
1A Terminal 1 of second lamp
1B Terminal 1 of first lamp
2X Black battery lead
2A Terminal 2 of second lamp
2B Terminal 2 of first lamp

When you are done wiring the alternative method, your circuit should look like this: