Astable circuit movement?

hi

im using the circuit and the calculator in this link
it works fine , but the movement from (low) to (high) goes very fast and sudden , and so the movement from low to high .
what i want is gradual (ascending) increase from low to high , like 4 seconds or something , then sudden decrease to low , then gradual increase to high again , and so on
what changes should i do , or what circuit should i use ?

any links or information would be helpful

thank you  :)

ARJOON7 years ago
sawtooth wave
frollard7 years ago
put a massive capacitor on the output to make it slowly come on.

You'll need to switch power to the capacitor AND after the capacitor to the load so it shuts of suddenly, rather than fading back out

You'll need a parasitic drain resistor to discharge the capacitor while its disconnected from power.
Won't work. Capacitor will be a short circuit when its discharged and a low impedance source when its fully charged, so it bye-bye output transistors.
Look at the voltage on the timing capacitor, and don't put much load on it.

Steve