Clicky switch - Main current from the battery flows directly through the switch. Usually found in tailcaps where one side of the switch connects to the driver through the body of the light and the other connects to the anode of the battery. Because main current flows directly through the switch, the conductive portions of the switch need to be beefy enough to handle the current. Clicky switches have a rotating internal piece similar to that found in a pushbutton ballpoint pen that allows the light to stay on after it has been clicked. They come in 2 varieties: forward clicky and reverse clicky.
Forward clicky - when the light is off a partial press without clicking will turn the light on, but it will turn off when the button is released. Depressing the button all the way will allow it to stay on when the button is released. This is often used in “tactical” single-mode lights because it allows quick momentary on-off. It’s not so good for multi-mode lights because quick on-offs change the mode. It’s also not usually used in pocket EDC lights where accidental half-presses in the pocket could result in the light turning on when not intended.
Reverse clicky - the light only turns on when the button is fully depressed and clicks to the on position. There is no half-press from off like in a forward clicky. However, once the light is on half-presses are used to change modes. This is the most common switch type in budget lights.
Momentary switch - (sometimes called a tact switch) current only flows the switch while the button is held down. There is no rotating clicky mechanism that allows the switch to conduct current when the button is released. Because these switches are mechanically simpler than clickys, they are less likely to wear out and may take less space. A momentary switch strong enough to conduct main current from the battery is almost never used in today’s lights, though in theory you could mod a light to one and have it as a tactical light.
Electronic switch - (also known as an “E-switch”) an electronic switch is composed of a momentary switch and special electronic circuit either in the driver or the tailcap. Unlike with a pure momentary switch, main current does NOT flow directly through the switch. Instead the current bypasses the switch completely and keeps the switch or driver circuit powered at all times. The switch itself is merely an input used to tell the driver circuit what to do, similar to the keyboard on a computer. In order to use an E-switch with a light, you’ll need to make sure your driver board’s firmware is designed for it. E-switches have numerous advantages: they are mechanically simple, so should last longer than clickys, they can be very compact due to their simplicity and lack of need to carry heavy current, they are quiet and they allow a very fancy user interface not possible with a clicky. The biggest downside is because the circuit is powered at all times, it will drain a small amount of current from the battery even when the light is off.
Switch wiring:
In a clicky, typically, the + and - of the battery should be connected directly to the driver. The - usually goes through the body of the light to the contact ring at the edges of the driver. This usually passes through the switch in the tailcap. The driver will have it’s own driver wires on the top of the body that connect to the + and - of the LED.
A typical E-switch driver is connected the same way, except that there will be an extra wire from the driver that passes through the E-switch and is then connected to the body of the light.
Some very rare E-switch lights may have the E-switch in the tailcap with its own circuitboard. In that type the E-switch simply takes the place of the clicky and is connected just like a clicky.
