modification for the data required from the ne555 to the masters of the electronics of the web

[[email protected]]

hi
I modified the maximum time that I want from the ne555 to
(~70sec)instead of 152sec can I get my minimum time (.001sec or
less)when I connect (2Mohm) variable resistance & cap 47uf what is the
minimum time which I can get it from the ne555 with this values?
because I connect pin(2,6&7)together then when I shorted the variable
leads together the ne555 freezing I can't understand this behaviour.
is this (astable mode)or (monostable mode)?
my problem :how I can calculate the minimum value of the resistance
which I can connect it to the discharge pin & get the minimum time
( vcc=5v c=47uf vr=2Mohm )

thank you for all help
yar

 

[Terry Pinnell]

hi
I modified the maximum time that I want from the ne555 to
(~70sec)instead of 152sec can I get my minimum time (.001sec or
less)when I connect (2Mohm) variable resistance & cap 47uf what is the
minimum time which I can get it from the ne555 with this values?
because I connect pin(2,6&7)together then when I shorted the variable
leads together the ne555 freezing I can't understand this behaviour.
is this (astable mode)or (monostable mode)?
my problem :how I can calculate the minimum value of the resistance
which I can connect it to the discharge pin & get the minimum time
( vcc=5v c=47uf vr=2Mohm )

thank you for all help
yar

Not that low. With the recommended limit of 1k, you'll get down to
about 50 ms. Use the simple approximation t = 1.1RtCt

How did you get a max of 70 s? That formula gives ~ 100 s.

Studying the NE555 data sheet would probably be useful also.