I hope you can help me with a circuit. Its a voltage sweep circuit that will sweep from 0v to10v in a 45 min time period, I'm using it for an input on a signal generator to control the output frequency.
I have tried a constant current source charging a capacitor but it just didn't seem to be solid. If It can be done digitally would be great! I have been struggling to do this and its the last part of the piece for my project.
Mail from CB in NA
I have once answered a similar question. Ramp Generator.
The constant current may not work as the capacitor may leak and it may not be a perfect ramp. The cc ramp is good for 1 second or less.
A staircase ladder ramp is best for you, define every step of ladder as say 10 or 100mV. A clock of 1 Sec is given to a counter, binary counts, and the digital output of counter goes to D/A Convertor.
"This design highlights the use of the LTC6993-2 and LT1490 to generate a pulse staircase ramp that is re-triggerable. "
Pulse Staircase Ramp Generator
If you wish to use a PIC, AVR or 8051 uC, then use it to time and control a built in D-A convertor or PWM. This is done in the code or firmware.
So .... clock >> counter >> digital to analog >> Ramp = you got it. You can implement in both software or hardware, it is your choice.