60Hz to 1Hz pulse source trouble

More
10 months 2 weeks ago #7544 by Ian
I was wondering why the KABtronics clock does it as a divide by 10 stage and then a divide by 6 stage, and I guess we just got the answer.... ;)

A divide by 10 needs only 2 inputs (8 and 2) and doesn't pass through any intermediate states which could cause a reset because of transients, and the same with divide by 6 (4 and 2).

I'm not sure how much of the KABtronics circuit I can post here without inducing copyright wrath and crossing the boundary to unfair behaviour. Suffice to say, that you're pretty close to what I saw in the manual.

Please Log in or Create an account to join the conversation.

More
10 months 2 weeks ago #7545 by wise65vw
I actually have their assembly instructions off the KABtronics website to get a feel for how they built theirs. Much more reliable using gates to dictate the operation of the counters. I can always add an extra flip-flop to the end and install some gates, but I want to avoid borrowing too much from someone else's design as this was supposed to be a logic exercise for myself.

The smoke means its working

Please Log in or Create an account to join the conversation.

More
10 months 2 weeks ago #7546 by wise65vw
I'm about to pull my hair out. I built the circuits the guys at KABtronics used to a tee. The divide-by-10 circuit produces a perfect 6.00Hz signal on the Oscope. The divide-by-6, however, STILL produces a 1.04Hz signal with their reset logic. I don't get it. The scope can measure frequencies lower than one, but is there any chance it could be wrong? I'm really at a loss here.

The smoke means its working

Please Log in or Create an account to join the conversation.

More
10 months 1 week ago #7547 by wise65vw
Okay, so i may have overreacted a bit. Also I think the oscilloscope might be lying. I've been leaving the clock running overnight to test accuracy, and interestingly, at night it seems to slow a little while during thr day it picks up. Additionally, so far for two days the amount of time it has been over or under (in seconds) has been roughly equal. I should mention that I only have my phone and computer as time references, and I've read that those may not always be perfect. I'll post a new thread showing off my build with pictures here soon, as it's nearing completion. And again, thanks much to Ty and Ian for the help with this project!

The smoke means its working

Please Log in or Create an account to join the conversation.

More
10 months 1 week ago - 10 months 1 week ago #7548 by Ian
This is a known effect for mains driven time sources. The frequency varies slightly with the load on the network, and the utility providers only guarantee average accuracy over a 24 hour period, but not instantaneous accuracy.

This is a good read: url=https://en.wikipedia.org/wiki/Utility_frequency]https://en.wikipedia.org/wiki/Utility_frequency[/url]

(Well, maybe not good, but interesting).
Last Edit: 10 months 1 week ago by Ian.

Please Log in or Create an account to join the conversation.

More
10 months 1 week ago #7549 by Ian
I was trying to find a display of the frequency variations, but it seems that in the US, this varies a lot by region and area. I come from a small country where there is a single grid, but on large, decentralised grids, this is up to the local utility company.

I have also been reading that the frequency regulation has been relaxed in the US (since 2011), and there is no longer a regulatory requirement to guarantee 60Hz.

I'm getting the impression that the Internet is a better source of time than the power socket.... :(

Please Log in or Create an account to join the conversation.

Moderators: AccutronTy_EeberfestIan
Time to create page: 0.033 seconds

Search

Tube Suppliers

Go to top
JSN Boot template designed by JoomlaShine.com