From time to time the accuracy of the 4060 as a timer comes up; 24 hours was brought up recently so I decided to check it out on BB. Cap, 3.3 uF metalized film @ 250 V, MKT 1813. Rx started as 2.5 M pot evolving to 680 k in series with 68 k, in series with 100 k pot. Was going to drop pot. down to 10 k for finer control but satisfied with 100 k. Manually counted sec. on low order stages, stop watch on even hours.
Clock = 5.27 s, stage 4 = 42.25 s, 5 =1 m- 24 s, 6 = 2 m- 45 s, 7 = 5 m- 37 s, 8 = 11 m- 15 s, 9 = 22 m- 30 s, 10 = 45 m, 12 = 3 h, 13 = 6 h, 14 = 12 h, 14 reset = 24 h.
First cut in 24 h = 3 m- 24 s slow, second cut = 2 m- 8 s slow, third cut with no further changes, 48 h ( not availavble at 24 h check ) = 24 s fast, 24 h today = 36 s fast.
Temperature 70 to 75 deg. F.
Not too bad for RC timer??

 

Using a crystal makes the timing very repeatable, but less adjustable. Deadly accurate if you design it right. I have found that an RC time constant, once dialed in, suits my needs very well...but I don't attempt to count for a month and then see how much that doesn't match, "real" time.

 

What is you long term accuracy goal? R's, C's, and pots literally change with the weather. Pots also change with vibration.

 

What is you long term accuracy goal? R's, C's, and pots literally change with the weather. Pots also change with vibration.

Nobody said there was an accuracy goal.
This looks like an experiment to find the native accuracy of an RC timer with adjustment pot.

 

Nobody said there was an accuracy goal.
This looks like an experiment to find the native accuracy of an RC timer with adjustment pot.

Oooookkkk...

Yes, you are right. I re-read his post, and it seems he was attempting to evaluate the potential stability/accuracy of a 4060 timer, with the conclusion "Not too bad for RC timer??".

Yet, the notion "not too bad" requires a reference? No?

 

Well, it has 2 question marks after it. Maybe he's waiting for an opinion from you?

 

Well, it has 2 question marks after it. Maybe he's waiting for an opinion from you?

Why you bustin' my chops, #12? I asked a question and made a comment. That's all. He's free not to answer if I was somehow out of line.

 

Besides, what does "using a crystal" have to do with evaluating an RC timer?

 

I didn't mean to come across cranky.
I gave my frame of reference: An RC timer suits my needs because I don't need to count time for a month. You can offer a different frame of reference if you like.

 

All's ok, #12.

Besides, if your weather is anything like ours today, you probably got too much sun.

 

All's ok, #12. Besides, if your weather is anything like ours today, you probably got too much sun.

The sun is lovely, but it's too cold to enjoy touching steel with bare hands. I can't even get warm by sitting in the van because it's only 80 degrees after baking in the sun all day. Yesterday it was 112 degrees in the van and that simply made my day! I was warmed up in ten minutes and glad to see the world...yesterday.

 

I've used crystal oscillators for ages, and yes, they can be quite accurate, especially if one uses OCXOs for that purpose... but in my experience, if you need to accurately keep track of time then an RTC chip is the best option