ISU Audio and Arduino Clubs

GTDT desktop amp project

The GTDT amp is the bigger sibling to the Altoids amp. It is a relatively low-power amp, but it can provide enough output current to drive a set of desktop speakers. The basic design is similar to the Altoids amp — two non-inverting op-amp circuit provide the same voltage gain. Following the op-amp gain stages are classic Class-B output stages using bipolar transistors to provide the current needed for bigger speakers. The amp outputs just a few watts of power per channel, but that is more than enough to drive speakers sitting on your desktop to reasonable sound levels.

To keep the design as simple and inexpensive as possbile, that amp is powered by a single supply — either a 12-V RMS transformer or an 18-V DC supply. This makes the power section somewhat trickier than the two batteries of the Altoids amp, and requires level shifting of the op-amp circuits. You can read about some of these details in the technical description linked below.

Most likely, you will want to put the GTDT circuit into a case of some sort. Standard input and speaker output connections would be part of the cae. Making a case for it will be covered separately.

There is no provision on the board for an on-off switch or volume control. If desired, those items can added as part of a case.

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