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Hello. I'm building a re-triggerable one-shot watchdog circuit using a 555 timer. I've got it working perfectly now. Except for one thing. When I run the sim,. the 555 outputs 5v on Output pin #3. Vcc is +5v. According to the 555 datasheet, shouldn't the output be 2/3 of Vcc? I'm new to 555 so I could easily have something wrong here. https://www.circuitlab.com/editor/#?id=mpv9czyt25u6 Thanks, -Hank

Nevermind. Looks like I can use a CMOS rail-to-rail 555 timer to get ~5v output.

The outputs of the 555s (on pin 3) swing from 0V to VCC. The voltage on the timing capacitor swings from 1/3 VCC to 2/3 VCC. That's where the 555's name comes from - inside the IC from 0V to VCC there is a three-resistor potential divider that sets these two voltages, and the resistors are all 5k.

Richard