juanMco
Newbie level 6
Hello all!
I am doing a design to charge/discharge a capacitor to generate pulse output for calibration measuring. I started the design based on a previous circuit done by another coworker. The stage is show below:
The circuit works properly doing the discharge when the square signal activates the npn. My issue now is the voltage divider stage, I tried to implement a relay-based attenuation stage using one rotatory switch with low tolerance resistive voltage dividers in L-pad configuration, but in some configurations due to a) the 20K output resistance and b) Time constant changes due to R change, it does not work properly, and my system needs high accurate.
The coworker explained to me that the original circuit used a switched power supply with variable frequency input, so it can achieved the desired voltage, but I cant do that at this moment because the design does not implement a logic unit (and original circuit got a micro).
So I am trying some way to implement this voltage divider. I am reading about zener diode divider, T-pad and Pi-pad attenuation stage,... but dont know if it will work for low voltage values. ¿Can someone you give me some new ideas to implement this? Maybe an IC or some circuits. Thanks in advance.
Regards.
I am doing a design to charge/discharge a capacitor to generate pulse output for calibration measuring. I started the design based on a previous circuit done by another coworker. The stage is show below:
The circuit works properly doing the discharge when the square signal activates the npn. My issue now is the voltage divider stage, I tried to implement a relay-based attenuation stage using one rotatory switch with low tolerance resistive voltage dividers in L-pad configuration, but in some configurations due to a) the 20K output resistance and b) Time constant changes due to R change, it does not work properly, and my system needs high accurate.
The coworker explained to me that the original circuit used a switched power supply with variable frequency input, so it can achieved the desired voltage, but I cant do that at this moment because the design does not implement a logic unit (and original circuit got a micro).
So I am trying some way to implement this voltage divider. I am reading about zener diode divider, T-pad and Pi-pad attenuation stage,... but dont know if it will work for low voltage values. ¿Can someone you give me some new ideas to implement this? Maybe an IC or some circuits. Thanks in advance.
Regards.