The blinker module uses a 555 timer, capacitor and a 500kOhm potentiometer, among other components, to output a square wave. The charging and discharging of the capacitor is what creates the oscillation of the current. A larger input current creates a higher frequency of the output wave, as it causes the capacitor in the module to charge and discharge faster. Since the capacitor on the module cannot be traded out, the input current is the only way to alter the frequency of the outputted square wave. The input current can be adjusted in two ways: changing the input voltage and changing the resistance. The input voltage can be altered by adding or taking away voltage sources. The resistance can be changed by adding resistors in series with the blinker or by turning the dial on the blinker to adjust the potentiometer.
Contents and Images credit: Circuit Scribe Website