I have this circuit. (Ignore the MOSFET for now.)
It's an astable multivibrator based on two BJTs. It works...kind of. There's two issues.
This is a sim of the output where R13 and R16 are 5k ohms:
I would like the fall times to be faster (any advice on how to do this would be appreciated), but I digress. It works.
Here's the same exact circuit where R13 and R16 are 10k ohms:
I think that this happens because I'm not limiting current from the voltage divider...I'm just decreasing the output voltage of the voltage divider which isn't what I want. In this case that voltage divider yields about .4V which isn't enough to forward bias the transistors.
In addition, here's what happens if the resistor values are too low: 1k ohms in this case...
In this case, I'm not sure why this is happening.
How can I use the RC time constant to my advantage while not changing the voltage I'm receiving from the voltage divider I want to "isolate" the original voltage divider and treat it like a rail.