How to Build an Audio Level Controller

Most electronics project consist of prototyping. They are begin with a prototype. This article will cover on building the concepts of prototype audio level controller.  Why audio level controller? Because audio level controller is a good example of the type of simple gadget that a beginning curcuit builder needs around the shop. it’s a quite common problems if you want to use the audio output of a music player as input to some other circuit or recorder but the output voltage of these device is often too high to apply directly to a recording input. That’s why in this case we need an audio level controller as a level reducer.

Building an Audio Level Controller

Before starting to build an audio level controller. We need to make a schematic of a simple level controller. You can see the schematic below.

Both left and right audio signals are connected to a variable resistor (R1 and R2, which also often called a potentiometer). The wiper of the pot (denoted by the arrow on above schematic image) slides along the surface of a resistive element (Resistor Symbol). The position of the wiper determines the resistance from the wiper. The wiper forms a voltage divider with one end of the element grounded and the signal applied to the other end. The voltage on the wiper become smaller as the wiper moves toward to the grounded element.

The total resistance of pots in controller is 1 kilo-ohm. If Ra = amount resistance from the signal end of the element to the wiper, and Rb = amount resistance between wiper and ground. Then Ra + Rb = 1 kilo-ohm. We can get the output signal level from wiper by using this

The output voltage gets smaller and smaller as the wiper moves along the element from the end at which the signal is applied toward the ground. The output signal can be varied from nearly nothing to nearly full input level. it allows almost any audio source to be used for the input signal.