Need Help 48 and 72 hour timer

Thread Starter

electrotech

Joined Feb 26, 2010
19
I am looking to create a timer that will trigger a 555 timer for an automated greaser. I want to be able to program the timer for either 48 hours or 72 hours. I read the previous thread using a 4060 binary ripple counter and I was wondering how to set up a binary counter to trigger at 48 and 72 hours. I am going to activate a transistor with the 555 timer which will activate a 24v pneumatic solenoid.
 

Wendy

Joined Mar 24, 2008
23,457
Something like this circuit could be used...

http://forum.allaboutcircuits.com/showthread.php?t=33015

An RC timer just isn't very accurate, figure ±10% is typical. If you can live with this kind of accuracy then you can use one, otherwise a crystal will likely be necessary.

What kind of pulse do you need after timeout?

If you still want to use several 4060's let me know, I'll help you design one. Since you want even increments of 24 hours it would probably be easier to also use a 4017 also.
 

Thread Starter

electrotech

Joined Feb 26, 2010
19
I am looking for a 1hour 5 volt logic 1 pulse at the end of the 48 or 72 hours what ever one is selected. I am looking for a circuit that will be triggered by a switch closing from a sensor through a dpdt relay. for example once triggered I want a 48 or 72 hour time delay once triggered. I will be using the output pulse to bias a npn transistor which will put 24 volts across a solenoid coil. The more accurate the better.
 

soda

Joined Dec 7, 2008
177
Here is a basic diagram for a CD4060 but you have to calculate the value's all by yourself. If you want to use a Cristal, you can place it in place of R1and R2. For a clock pulse you can use a NE555 astable. The thing is, I did this a few years back and totally forgot all about c-mos because i don't use it anymore and that is because i rust up, so good luck
 

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Wendy

Joined Mar 24, 2008
23,457
OK, can you stand the ±10% variation on the on pulse? It can be adjusted closer than this with a resistor, but there will still be a lot of drift.
 

Thread Starter

electrotech

Joined Feb 26, 2010
19
Yeah 10 percent tolerance would be all right. So will a 4060 get me that close or will I have to go with a different method. I am pretty rusty on my digital I have been a tech for 5 years now and I havent used it since school.
 

Thread Starter

electrotech

Joined Feb 26, 2010
19
so why are only 2 of the 10 outputs used, and is there a formula for calculating the RC circuit or how would I figure the time if I put a crystal in place of R1, and R2
 

Bernard

Joined Aug 7, 2008
5,784
My notes show: F=.7/[RxCx]. Rx to pin 11, pin 10 = 3 to 10X RX, Cx to pin9, other ends tied together.
Have you considered line frequency for clock? Great long term accuracy.
What is your line frequency? 50 or 60 Hz.
 

Wendy

Joined Mar 24, 2008
23,457
I'm assuming from the original post it is an internal clock, hence the talk about using a crystal oscillator. I've been up way too long, so I'll have to get back to this after some shut eye.
 

Wendy

Joined Mar 24, 2008
23,457
OK, I'll explain what I'm doing as I figure this out. I'm designing from the ground up.

Figuring a ½ second clock (2 Hz), you need the following binary number for a 24 hour period.

10101000110000/0000

I've already done a basic binary check, the 4060 has the outputs to do this. Some of the internal ripple counters are not brought out to pins on a 4060, so you have to do a basic design check to see if it can be done in a straight forward manner. It can.

A 4060, in addition to being either a crystal or RC oscillator, is a 14 stage ripple counter. This is why I have the slash in the binary number. It will take 2 additional 4060s in addition to the time base 4060 to reach the binary number involved.

A question about operation, do you want the timer to stop operation once it triggers, or to keep counting on? If it keeps counting on it will trigger every two or three days, depending on your choice. With a time out condition it will stop and wait for another manual input to start timing. This has to be decided now, early in the design process.

Here is the basic time base, straight out of the data sheet. I figure a crystal is required since you want some basic accuracy out of this sucker.



If you're building this as a breadboard it is not too early to build this time base. You can not use a protoboard, since the crystal section is finicky about such things. I recommend the Manhattan style or dead bug style of building.

I have a pile of parts for a future project involving an Altoids can for just such a time base I'll eventually get around to building.
 
Last edited:

soda

Joined Dec 7, 2008
177
This is a drawing of a timer i used to run my water irrigation system a few years back. I show you this so you can work from here. Check out the next schematic to see what outputs you need for your timer
 

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Wendy

Joined Mar 24, 2008
23,457
My notes show: F=.7/[RxCx]. Rx to pin 11, pin 10 = 3 to 10X RX, Cx to pin9, other ends tied together.
Have you considered line frequency for clock? Great long term accuracy.
What is your line frequency? 50 or 60 Hz.
Bernard is right about using line frequency as the time base. I'm following the assumption you want portability, but this may not be the case.

So this is another question in addition to the continuous loop or stop on time out query.
 

Wendy

Joined Mar 24, 2008
23,457
The schematic for the basic 4060 time base is incomplete. I was in the middle of changing it when the site died. I'll be reworking some of my graphics for the 4060 and repost it when I'm done.
 

Bernard

Joined Aug 7, 2008
5,784
I assume a fixed location as there is a 5V & a 24V supply, operation triggered by a "sensor" closing a switch [?momentary?]. If so, operation is a one shot, with every thing reset at last bell. With 60 Hz: 4093 for shaping & memory, 4040 /512, 4040 /3395, 4017 or 4022 /3 [days], 4017 or 4022 / 2 or 3 for 48 or 72 hr sw selected, 555 or decode existing counters for one hr,[ /512 & /422 for one hr.] + misc invertors & NAND getes.
 
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