The internal DS1669 is made up of 64 micro-switches and of their respective resistances, which we can control by means of the double push buttons useful for sequentially increasing or reducing these resistances that are found inside the DS1669.
When power is switched off, the circuit is able to "remember" the point where it was.
If you keep the button pressed, you will be able to turn the volume up or down quickly (as you press P1 or P2). Finally, the power supply must stand between 4.5 and 8 volts DC .
The circuit board.
The real size is 25mm high and 36mm in width.
The scheme and the circuit board should be in the same folder and they should have the same name, you should only change the extension to .sch for the scheme and to .brd for the circuit board, this way both of them will be recognized and associated by Eagle.
The file is compressed, to extract it, you should enter a password: www.kemisa.es
If you don´t know how to make a printed circuit boards click here.