I don't know what a sem level is but the standard 555 astable circuit is good fun and anyone over 9 years old should be able to make it, most people over that age have the potential to understand it too.
Regarding the circuit diagram there, you don't need the cap on pin 5, I allways leave it off my 555 timers and they're fine, however if you have problems, it may be because that cap is missing.
Why don't you see if you can make a basic remote control for a TV or stereo system out of 555 timers. Just on/off and a few functions would be sufficient. That should be at least a little challenging.
Why don't you see if you can make a basic remote control for a TV or stereo system out of 555 timers. Just on/off and a few functions would be sufficient. That should be at least a little challenging.
Most appliance remote controls operate on or about 38.5kHz and use relatively simple modulation schemes such as pulse width (PWM) pulse position (PPM) or on-off keying (OOK). The carrier frequency is well within the capability of the 555 and it might be possible to hard wire the needed modulating codes into separate 555's to modulate the carrier for each control function. It may be feasible to build such a thing.