how a 555 works(astable operation)
the 555 gets its name from the three 5-ohm resistor.these resistors act as a three-step voltage divider between the supply voltage and ground.comparator flip flops top output power supply.memory modulation may be needed.notice a model card.relay driver an branch circuits to  a conventional amp.trouble shooting  the contacts.practical timing flip flops locking high low mid range.possible.logic probes.in which in turn.combination circuits.available configurations serial out serial in. amplifiers hysterisies that are both non inverting multiplexed  556 558 in which contain four.the 556 contains two/relay driver  to photransistor with a voltage gain.