A do-it-yourself digital potentiometer project is a great opportunity to learn about the quantised nature of digital electronics. In this audio level control circuit, the DS1669 IC serves as the core. It is a digital potentiometer integrated circuit, which means that its resistance is adjusted in steps. Since it is purely electronic, the IC has no moving parts to wear out. You adjust the potentiometer by pressing momentary buttons to step through its resistance values. This circuit is extremely simple.
- Skill level:
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Things you need
- DS1669 IC
- Solderless breadboard
- Wire jumpers
- 2 Momentary switches
- .01uF ceramic capacitor
- 2 batteries, AA
- Input and output wire
Insert the pins of the DS1669 in the breadboard, with the two rows of pins straddling the centre ridge.
Twist the wire lead of a jumper around the terminal of a momentary switch with needle-nose pliers. Do this for both of its terminals. Repeat for the second switch. Connect a different jumper to each terminal.
Insert one wire lead of a switch's, S1, jumper into pin row seven, which is the row of breadboard pins shared with IC pin seven. Refer to the IC's datasheet to identify pin numbers.
Insert the other lead into the ground rail, which is either of the two outermost rows of holes along the length of the breadboard. These two rails runs perpendicular to the other rows and are electrically isolated from each other and from the rest of the breadboard.
Insert one lead of the jumper of the second switch, S2, into pin row two.
Insert the other lead into the ground rail.
Connect IC pins four and five each to the ground rail by inserting a short jumper between the last hole in each pin row and the ground rail.
Insert one lead of the capacitor in the ground rail, and the other in pin row eight.
Place the batteries in the holder.
Insert one lead of the battery holder in the ground rail. Insert the other in the unused rail, which is called the power rail.
Place a jumper between the power rail and pin row eight.
Connect the input wire to pin row one and the output wire to pin row six.
Use the S1 and S2 switches to adjust the resistance of the potentiometer.
Tips and warnings
- Use this circuit to control tone, brightness, volume, contrast or a dimmer.
- Set audio levels carefully to avoid hearing damage.
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