T-Rex Engineering TremsterDeep, buttery, and seductive. Designed to create vintage tube amp tremolo, the Tremster uses a light dependent resistor (LDR) to achieve its deep, buttery, and seductive sound. A flashing LED displays the current speed and permits a wide range from very slow to seizure inducing head spinning. With the Mode knob in the normal position, the Tremster has an aggressive, sine wave type effect. Depress the mode button and the effect is less aggressive with