Volume 1, Issue 2, February 2015 - Page 15

151

Obscure Adventures Magazine

three additional momentary switches: a rocker switch that I use to control electric tilt/trim, a push-button that acts as a remote kill switch for the kicker and a dead-man switch that I haven’t decided how to best use yet. All of these switches provide a very simple function – completing a circuit.

In a simple electric circuit there is the power source and the load, for example a battery and an electric motor. If you connect the battery to the motor it will start to work and it will only stop if the power is removed, like when the battery dies, or if you break the circuit by using a switch.

The switch is a simple device that breaks either the positive, or

negative, side of the circuit and it has to be rated to handle the amount of current the load requires.

It’s important to understand that if you run a 50 amp device on a switch rated at 20 amps it will often fail quickly. High amperage devices, like a starter on a car, or outboard, require large wires and beefy switches to carry the necessary current.

At times you may not want to run high amperage switches due to the cost. The solution is the relay. A relay is a switch that contains an electromagnet that closes, or opens, with low current.

When the relay engages it allows high current to pass through to power the load. They have been used for decades in the automotive world. The 40 amp “Bosch” style relay is what we’ll focus on here due to its availability and low cost.

In the diagram on the next page you will see the assign-ments for each post on the relay. This relay can handle a normally open (the load is off until the relay is activated), or a normally closed (the load is active until the relay stops it) situation.

The real advantage in running the relay is that the low-voltage needed to activate the relay permits long runs of small diameter wire and lower

amperage switches, which can save money.

(continued on next page 16)

The video on the left demonstrates how the joystick contacts the four microswitches on the X and Y axis. Pushing the joystick down in this case engages the switch to the front.

These microswitches, similar to the one above can be wired to either open a circuit, or close a circuit. Controlling an actuator usually requires use of the normally open option. Otherwise the actuator would be working non-stop until the switch is engaged.

Examples of the momentary switches on my joystick.

Top: A very common style of relay that works at 12 volts and has a rating of 40 amps. EBay is a great place to find deals on relays and pigtails in higher quantities.

Middle: The numbers on the relay are confusing, but the diagram on the next page will show how to wire two relays to control an actuator.

Bottom: Pre-made pigtails help installations go faster.