The function of the volume adjustment limiting resistor circuit is to limit the range of the volume control, and the volume cannot be turned to the maximum or minimum. This circuit is used in some special volume control occasions to prevent the impact on the working status of other circuits due to improper volume control.
The so-called volume adjustment is the function of adjusting the sound level in televisions and other electronic appliances. The circuit is called the volume controller circuit, which can turn the volume to the maximum and the minimum (the silent state, commonly known as the dead volume).
As shown in Figure 3-23, the volume adjustment limiting resistor circuit. One thing to understand when analyzing the operation of this circuit: the volume limit of this circuit is relatively the case without RI, R2.
(1) The volume cannot be minimized when RP1 is adjusted to the lowest end (compared to the circuit when there is no R2), because there is some signal voltage drop on resistor R2, and this signal voltage drop is sent to the subsequent amplifier through the RP1 moving blade, so The circuit cannot turn off the volume to achieve the purpose of limiting the minimum volume.
(2) When RP1 is turned to the top, the volume cannot reach the maximum (compared to the circuit without R1), because there is some signal voltage drop on resistor R1, which achieves the purpose of limiting the maximum volume.