in basic 555 timer circuits,there are two resistor and 2 capacitor ( one in pin 5), 4 and 8 connect to Vcc,and then they run,simple!
now i want to control it!
i disconnect pin 4 (floating),the 555 no OSC.Reconnect it to Vcc,555 run again
so i used NPN transistor(ex: C1815),C to Vcc,E to 4,B have a resistor and connected to controller.Result : in logic 0 and 1,555 still run.(no problem with transistor)
in fact,if i use PNP transistor ( Ex: A1015),E to Vcc,C to 4,B have a pull-up resistor and connected to controller.There are no problem.Logic 0: 555 run,logic 1:555 off
anybody ask me why ?
now i want to control it!
i disconnect pin 4 (floating),the 555 no OSC.Reconnect it to Vcc,555 run again
so i used NPN transistor(ex: C1815),C to Vcc,E to 4,B have a resistor and connected to controller.Result : in logic 0 and 1,555 still run.(no problem with transistor)
in fact,if i use PNP transistor ( Ex: A1015),E to Vcc,C to 4,B have a pull-up resistor and connected to controller.There are no problem.Logic 0: 555 run,logic 1:555 off
anybody ask me why ?