This page shows the operation of the venerable 555 timer IC, showing signal traces at various points both inside and outside the IC
This table shows the state the IC is in in realtime.
| STATE | Vcap | S | R | OUT (Q) | DISCHARGE (Q) | TIME IN STATE |
|---|---|---|---|---|---|---|
| Vcap < ⅓Vcc | High | Low | High | Off | ||
| ⅓Vcc < Vcap < ⅔Vcc (capacitor charging) | Low | Low | High | Off | ||
| ⅓Vcc < Vcap < ⅔Vcc (capacitor discharging) | Low | Low | Low | On | ||
| Vcap > ⅔Vcc | Low | High | Low | On |