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Re: 555 ic timer
You can find the datasheet here:
The fomulas you want:
Charge period (output high):
Discharge period (output low):
Total period T is t1+t2, from there you can calculate...
Re: is this SAFE?
Standing on insulated desk will prevent earth return path, but won't help much if he touches woth live and neutral.
Mains voltage is very dangerous, and is not to be taken lightly! If you ask if it is safe it probably means you are not very well aware of risks, so DON'T do it...