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wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 02:18am 27 Apr 2019
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My ponderings on the 50Hz accuracy after considering implications of accurate oscillators & integrating to a nano (our nano modules all use a crystal - I haven't seen one using a resonator) etc:
We have a AA battery clock in the kitchen which we replace a battery ~ every 2 years. It is large easily readable and our time reference apart from looking at your mobile phone. The clock gets adjusted to correct time at least twice a year for daylight saving correction and I cant remember ever needing to adjust it in between.
We ignore the clocks on the oven, microwave, VCR (whatever that is...) etc. Our PVR is set to adjust to broadcast time and is always correct.
We have a couple of bedroom clocks but they use a Dallas chip and have a Lithium CR2032 backup battery - a good indication that it probably ignores mains frequency variations.
I think the Kiss principle may apply here and buying a reasonable bedside clock is the only real expense that might be necessary - for all those here that are retired now and have time to play inverters, who still sets a clock to wake up ? If I have a flight to catch I use 2 x mobile phones and set their alarms. As far as the oven, if we're cooking a roast for 2 hours whether it starts or ends a few minutes out is not an issue.
Maybe there are other considerations, but in my household I cant see me being fussed by a semi inaccurate 50Hz. Maybe if it is a big enough problem for some a new design of a nano module with a better clock (think TXCO) oscillator - you can easily get 0.5ppm temperature compensated accuracy for just a few dollars, is the way to go ?
Edited by wiseguy 2019-04-28If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
poida Guru Joined: 02/02/2017 Location: AustraliaPosts: 1419
Posted: 02:48am 27 Apr 2019
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Maybe for those still connected to street power could sync up the nanoverter with mains to use that long term stable time source.
But a TXCO would be brilliant.
Everyone I know uses a mobile phone for alarm.wronger than a phone book full of wrong phone numbers
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 03:20am 27 Apr 2019
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Agree with all of the previous comments.
Just pointing out this frequency accuracy issue as something to be aware of.
It does not worry me, the only mains synchronous clock I have is in the bedroom, and the only reason I have kept that, is that the LED display brightness changes automatically with room light levels, which is a worthwhile feature. Edited by Warpspeed 2019-04-28Cheers, Tony.
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 10:46am 27 Apr 2019
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While we are discussing clock accuracy, I built a TTL logic (remember that?) based 60LED in a circle clock in the early seventies. It used a 1MHz crystal for a time base. It was fiddly to set the ceramic trim caps just so to have it keep a reasonable time. And it suffered from temperature changes despite the heating effect of dozens of TTL chips.
Then it spent a long time disconnected sitting on a shelf collecting dust. For sentimental reasons I resurrected it a year or so ago and yes, the TTL chips are still running fine. But to keep accurate time I fitted a GPS module that outputs a 1 second pulse, accurate to a atomic clock . These things can 'see' the satellite signal in the middle of my timber frame house with a tile roof, remarkable..
Do I need that accurate a time? No, but I did it because I can. Isn't technology great? Klaus
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 08:40am 29 Apr 2019
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The little power modules I had ordered have arrived. They are quite different from yours wiseguy.
You can see those can accept a continuous header connector, so far so good.
Then I started testing it
Problem 1, they need 63V to start up. Could be overcome with my DC/DC booster board. Problem2, have no idea how to modify the output for 15V. Most of the smd parts are under the little transformer, so can't get at them. There is a 1K2 resistor across the output terminals, changed that to bigger & smaller values (1K8, 1K) which did nothing to change the 12.5V output. There are 2 470K resistors in series with the input. Changed one to 100K, this did not lower the start up voltage one iota .
So it looks I have to order the 15V modules I saw in your link - not cheap by the time 18 of them plus postage plus tax are added on. Klaus
wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1156
Posted: 06:57am 30 Apr 2019
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Thats kind of like a "Ive got good news and bad news story"
The good news is the 0.1" spacing - sorry to hear the bad news part.
Maybe you could sell the others on the forum - there is no simple answer to adjusting the voltage if you cant get at the bits?
Look on the bright side, at least you wont have to use a boost supply. You could even use them as green night lights If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 10:50am 30 Apr 2019
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That's how I see it too . Not worth the postage to sell them but I could parallel all 20 of them, connect to the mains and get a high power (20 x 3W ) 12v power supply .
I did order the ones you got but with a 15V output, of course their price goes up with the higher output volts too.Klaus
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 10:08am 19 May 2019
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For anybody still chasing DC/DC modules like the one pictured, I finally received mine and they are indeed excellent. They are much smaller than some of the modules mentioned before. I got the 15V version so, no mods required.
Placing a 100R load at the output, each of my 18 modules started up at 40V DC input. The output was 15V +- 0.1V, most were just over 15V with that load. These are only 2W rated so the 100R load was pushing it past 2W, could not ask for more.
I got mine from aliexpress . There are similar ones without the pin connectors on ebay, these, which I got in 12V version, did not start until over 60V DC input.Edited by Tinker 2019-05-20Klaus
noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513
Posted: 10:34pm 19 May 2019
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Could you please post a link Klaus I think it works !!
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 09:29am 20 May 2019
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I tried posting a link but then when I clicked it in the 'preview message' feature it said the link was expired .It did that twice so I deleted it to avoid misleading people. I'll try again shortly with a copy & paste job .
Hopefully that works. Choose the 15V version for the warpinverter, they cost a little more unfortunately. I will have PCB's for that driver in a week or two.Edited by Tinker 2019-05-21Klaus
noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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. These things can 'see' the satellite signal in the middle of my timber frame house with a tile roof, remarkable..
.
) 12v power supply 
.It did that twice so I deleted it to avoid misleading people.