Improved Headlight Circuit for Motorcycles
Many motorcycles are equipped with a feature where their dipped headlights or daytime running lights automatically activate when the ignition is switched on. However, on most modern bikes, these lights briefly turn off while the engine starts to prevent putting a heavy load on the battery. Nevertheless, there are exceptions where this feature is not present. The following circuit description offers a solution to this drawback.
Optoisolator IC1 Detects ‘N’ Light for Gear Status
The circuit’s core component is the optoisolator IC1, responsible for detecting the status of the ‘N (neutral)’ light, La1, on the dashboard. As long as La1 remains illuminated, the machine is in the ‘N’ gear. When the engine is started while the gearbox is still in ‘N,’ La1 stays lit, causing the LED in the optoisolator to activate. This, in turn, triggers the transistor within IC1, putting the thyristor gate at high potential and keeping the relay de-energized. Consequently, the headlights La2 and La3 stay off, allowing the engine to start without these lights coming on.
Engaging a Gear Switches off La1 and Activates Thyristor
When a gear is selected, La1 goes dark, leading to the deactivation of the transistor in IC1. This change allows the thyristor to receive gate current via R2 and R3, subsequently energizing Re1. The headlights then come on, and the machine can be safely driven away. Importantly, the thyristor remains active as long as the battery is being charged. For instance, when “N” is selected at traffic lights, the lights stay on thanks to this feature.
Understanding Optoisolators and Their Applications
Optoisolators, also known as optical couplers, photocouplers, or optocouplers, are semiconductor devices that transmit electrical signals between isolated circuits using light. These components are integral in various communication and monitoring systems that require electrical isolation to shield low-power circuitry from the effects of high-voltage emitters. Optocouplers are versatile and can function as standalone switching devices or be incorporated into other electronic systems to provide isolation between low- and high-voltage circuits. Common applications include microprocessor input/output switching and DC and AC power control.