Simple45min timer

[kaushik011]

Need a timer
Preferably 4060 or 555 with some extra components

1)
Timer : 1 – 45Min
2)press to start ,a soft push should fire the timer .
This is because I don’t want the timer to fire always on power on.
example : if I am heating a glass of water with eggs via heater element
if power goes off and resumes , timer should not make heater on.

It has to make it on when I press soft switch.(just push,no latch)
After expiry sd make my device off ,relay is ok

I made it in college … lazy to redesign

 

[alec_t]

Something like this? Replace C2 with a momentary push-switch.
http://www.electronicecircuits.com/electronic-circuits/cd4060-timer-circuit-1-minute-to-2-hours

 

[kaushik011]

That is good one , thank you !
But the soft latch part is missing , w/o it the time will auto start w/o my permission

so encounter problem is power cut -resume happens

 

[alec_t]

I made it in college … lazy to redesign

Well why can't you make it again? Why be lazy?

 

[kaushik011]

now a days i am pulling my hairs in job ... just 8 hour weekends dont let me design these , again i like the idea of replacing c2 ,
if this works as needed ,it saves build time , also components..

expected operation
-power on , timer inactive
-press push, timer counts down , appliance is on
if
-power cut ,power resumes, obviously timer is inactive

 

[alec_t]

In post #1 you say "It has to make it on when I press soft switch.(just push,no latch)", whereas in post #3 you say
"But the soft latch part is missing , w/o it the time will auto start w/o my permission". So which do you want? Latch or no latch?

 

[kaushik011]

soft latch is action [latching action in electronics ]..............
seems your circuit may fulfill this

Start timer switch is a pushbutton not a latch switch[like rocker switch post1], as if we use mechanical latch switch
timer will always start on power failure->resume

 

[alec_t]

To meet your requirements fully I now think the circuit in the link won't do and a momentary switch plus a latching circuit will be needed.
Here's a possibility, simulated with LTSpice. I don't have a sim model of the CD4060 so used a CD4020 model instead. I've marked up the changes needed for use with a CD4060. An LED can be added as in the previous circuit if you wish.