R-2R D to A Converter

This is a little R-2R Digital to Analog converter breadboard adapter.

Disclaimer and License
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Description
Having recently started playing with ┬ÁControllers, I wanted to experiment with converting a digital signal into an analog voltage. The easiest way to accomplish this is by using an R-2R resistor ladder.

bottomThis simple project is really just a PCB board layout for a R-2R breadboard adapter I made to experiment with Digital to Analog Converters (DACs). For my breadboard adapter, I used 10K and 20K 0.5% 0805 SMD resistors. These were reasonably priced from Digikey, but you can use any values you like as long as one is R and the other is 2xR.

To save real estate on my breadboard, I prefer to have my adapters stand up as in the photos. However, you can also make this board in a horizontal configuration on 0.500″ centers that should easily fit in any breadboard as well. One thing you will notice that is a little different about my board is that you can use it as anything from a 2-bit DAC to an 8-bit DAC.

topIf you would like to experiment with a 4-bit DAC, connect the input bits 1 (LSB) through 4, and leave the input bits 5 through 8 (MSB) floating. Then read from the 4bit DAC output pin. For a full 8-bit DAC, connect all the input pins to your ┬ÁController and read from the 8bit DAC output pin. In general, connect up to n input bits and leave all others floating. Do not connect the other input pins to ground or to Vcc. Read the output of the DAC from the n-bit output pin.

boardThis is a very simple single sided board made using the toner-transfer method.

Disclaimer and License

It worked for me so it should work for you, but no guarantees. Feel free to use the schematics and information on this page as you see fit, but a little attribution would be appreciated.

Project Sources