555 timer 50% duty cycle question

if you look at how the standard circuit works, you will see that, whilst it discharges the timing capacitor through a single resistor, it charges it through that resistor plus a further one. Hence the time to charge is greater than the time to discharge.

Just alter the circuit so that it charges and discharges through the same total resistance. Hint: This will require an additional resistor.

However, if you want an accurate 50% duty cycle, you really need to add a divide by two to the output.

There are different ways to do it: . Connect the charging resistor not to Vcc but to the output . Use diodes to have different paths for charging and discharging The circuits are available on the Net. Just google for it. Gene