This is a R-2R Digital to Analog Converter, It converts a byte (8 bit) to a analog value. It has 256 levels including zero.
This was the first Digital Pot i Built decades back - Digital Potentiometer
This can be used to convert a byte sent from a microcontroller to a analog value like say 1.51 V. At full scale, when all 8 bits are high calibrate to give 2.55 V then ever bit increment is 0.01V, 10mV steps.
Printer Port Circuit to see the inputs logic state and drive a few outputs. The preset control program helps test out the circuit operation. Use safe 5V Levels.
This circuit uses a R-2R Ladder Resistor Network to convert digital data from PC Printer Port to Analog. This can be used as a Millivolt Source or Programmable Power Supply.
This is a Test Circuit for Logic Analyzer software, with the Simple port circuit. The VB Logic Analyzer works, but is just an example program to test and learn.
Test Circuit for Logic Analyzer software - del20006
The speed at which the logic state changes say like 10 M Hz while probing even a PIC or 89C51, is too fast for this circuit. For that, the incoming data has to be spooled or stored in RAM at real time, by the external Hardware itself.
Using this circuit on Printer Port, one could drive 256 Relays or 16K LEDs as Dot Matrix display. It can be used to drive a Large size multiplexed LED dot matrix display or Latched Relay-Solenoid-Motor-Lamp Array Drivers.
Printer Port 256 Relays 16K Dot Matrix - del20021
This circuit can be modified for a Static drive output or a fast changing output like a Waveform Generator. You can also make it a 16 Bit waveform generator. The frequency limited to the speed of the port or a fraction of it, depending on 8bit, 16bit or 32bit.