Sample and Hold, Noise, and Slew Limiter

Status: Built

My sample and hold and slew limiter is based on Moritz Kleins design for an analog sample and hold circuit, however I made a couple of tweaks to the design.

First, I wanted a longer hold period so I added a switch and a bunch of capacitors to Moritz’s design so it could toggle between a fast range of sampling rates and a slower range of sampling rates.

Second, I thought that the slew limiter could be enhanced a bit, so I followed Midcentury Modular’s design to break out the slew rate for rising and falling voltages to separate controls, and a switch to toggle between linear and exponential response in the slew circuit.

Future Improvements

• To speed acquisition time and prevent droop, move to a digital sample and hold circuit.
  • The ADC080X appears to be the compliment to the DAC0800 used in the shift register, and it might even latch. Only issue is it’s 0 to 5 volt range.
  • Conversion approach for inputs
    • Input (say -5 to 5V)
    • Add 5V (now 0 to 10V), with switch to skip this step for inputs that are expected to be 0 to 10V
    • Divide voltage (now 0 to 5V)
    • Buffer
  • Conversion approach for outputs
    • Output from DAC (0 to 5V)
    • Amplify (now 0 to 10V)
    • Add -5V (now -5 to 5V), with switch to skip this step for outputs that are expected to be 0 to 10V
    • Buffer