timer with more than 2 or 3 days delay

absf

Joined Dec 29, 2010
1,968
U1 clock period = 10.546875 sec, so after 8192 counts we have 86400 sec or 1 day.
There are 2 parts in U1 4060. First part is the RC oscillator which generate a clock of 12.546875 sec. or 0.094814715Hz. Then the clock is further divided down by 2^13 (8192) to get 86400 seconds which is equal to the duration of one day.

24 hr*60 min*60 sec = 86400 seconds.

So what is coming out of 4060 at Q14 is actually one day. So that makes the task of 4017 decade counter easier. What comes out from Q1, Q2, Q3 & Q4 are 1 day-pulse, 2 day-pulse, 3 day-pulse, and 4 day-pulse.

Allen
 

Bernard

Joined Aug 7, 2008
5,784
On solderless breadboard U1, Q 14, went high 12 h, 9 m; small tweek, ie, 1 CCW turn of 20 turn pot & then Q14 went low at 24 h, 10 m; close enough?
R1 =120K, R2 100k, 20 turn " Trimpot", R3 1M, Cx 1&2 20 μF, +- 20%, @ 35V [ combination measured 11.9 μF.], R4, 1M.
Timing was set with stop watch & LED test light. First , U1- pin 9, R2 adjusted for 5 sec full period, up & down. Q4-7, on @ 42 s; Q12-1 @ 3 h; Q14-3, high @ 12h, lo @ 24h.
Q14-3 goes lo @ 24 h, which is inverted from U2 clock requirement- hence need for U4 inverter. Could eliminate U4 by doubling clock & resetting U1 @ 24 hr. Still problem with U2 reset- later.
Desired operating V ??; Relay V & Ωs??
 

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DMahalko

Joined Oct 5, 2008
189
If accuracy is not highly important, maybe a simple analog circuit would do what you want.

Use a large capacitor (or parallel group of small caps) with a high-resistance trickle-charger.

When the capacitor voltage rises to a set point, activate the pump and drain the capacitor for the next charging cycle.


Pumping can be similarly timed with another trickle charging capacitor, which when activated, runs the pump until the voltage set point of the second capacitor is reached. The pump turns off, the capacitor is drained, and waits for next activation pulse from the main timer.


(I do not have any circuit suggestions for this, though.)
 

Bernard

Joined Aug 7, 2008
5,784
Best I could get with a single 555 was about 3 hours using 16,000 μF; then leakage & charging current started fighting.
 

MMcLaren

Joined Feb 14, 2010
861
It sounds like you may not have local resources for a microcontroller based solution, but if you did, something as simple as this livewell pump timer circuit could be modified to use a two, three, or four day period with an adjustable "on time" interval from 1 to 30 minutes or so.

Food for thought. Good luck on your project.

Cheerful regards, Mike

 
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