This is a hearing aid circuit with 1.5v supply. This circuit is used to detect very faint sounds, then deliver the sounds to an 8 ohm earpiece. This circuit requires 1.5v input voltage, need only a single cell battery. Here is the schematic diagram of the circuit:

HEARING AID 1.5v SUPPLY circuit schematic

This circuit can be assembled in a small board, or you can even do it without board. To assemble without board, you can connect every component leads each other and solder them. Align the component bodies and their leads to avoid shorts, secure with insulation tape, glue, or resin.