Correct tool, for converting 60hz to 50hz - Page 1
Forum section: electronics / beginners

author: kingofkya
author_rank: Regular Contributor
timestamp: July 23, 2014, 10:19:48 pm
content: I have a project that involves dimming with leading edge dimming anyway. I want to test with 50hz input to make sure my code works. So whats the correct tool for the job. Steeping up voltage is easy but i am not sure exactly how to to manipulate the speed.I read about using two generator motors running at 50 and 60htz to do the conversion mechanically but i would rather not have 2 useless motors sitting around after this project.I only need to test up to 400ma or so at 220V so it dosen't have to be massive. I am in the US so I have 120v AC @60htz.

author: edpalmer42
author_rank: Super Contributor
timestamp: July 23, 2014, 10:45:28 pm
content: Some of the fancier UPSs can change the frequency. You need a unit where the load is always powered by the inverter. I have a Liebert UPStation GXT that has a feature like that in the manual, but I've never tried it. You'd still need a transformer or autotransformer to step the output up to 220V.An even more devious way is to take an audio oscillator set to 50 Hz and feed it into an audio amp that's rated at 100W or more (since your load will be about 90W). Then add a transformer to take the output from the amp and boost it to 220 V. For example, a transformer that's designed to take 220V to 24V would be about right. Obviously, the transformer would also have to be rated at 100W or better.Ed

author: xygor
author_rank: Regular Contributor
timestamp: July 23, 2014, 10:55:15 pm
content: 1.) Omit 1/6 of the cycles. Probably not what you want though.2.) Use a 50 Hz sine signal generator into a power amplifier.Edit: Oops. I see Ed already said the #2 choice. It's not dubious though.

author: Smokey
author_rank: Super Contributor
timestamp: July 24, 2014, 01:57:03 am
content: What you really want to do is convert the AC into DC then convert it back into AC of a different frequency. That involves rectifiers, filters, and amplifiers. Pretty much the guts of a UPS or one of those plug into your cigarette lighter inverters for the second half. Depending on how "clean" you need the AC to be that can be kind of hard or really hard to make from scratch.Here is a thought... Do 12VDC to AC car inverters that come from Europe convert to 50hz? Could you import one of those?Which brings up an interesting question. Has anyone tried hacking either a UPS or 12VDC to 110AC inverter? That seems like it might be cheap source of a cool piece of equipment if you could control it more. Open firmware for something that can be reprogrammed maybe?

author: Richard Crowley
author_rank: Super Contributor
timestamp: July 24, 2014, 02:24:38 am
content: "Conversion" involves a 60Hz motor connected to a 50Hz alternator. This is the old-school solution our grandparents used."Generation" involves using a 50Hz oscillator and a general-purpose amplifier. This is the more modern solution that our parents used."Emulation" involves simply taking the difference into account and changing the firmware parameter. This is the current solution.OTOH, you could simply send a prototype to a friend in 50Hz-land to alpha-test for you.Considering that the only difference between 60Hz and 50Hz is the length of the cycle, this seems easily calculated and very low-risk.

author: richard.cs
author_rank: Super Contributor
timestamp: July 24, 2014, 08:51:58 am
content: Suggestion 1: Buy a cheap 50 Hz 12V-240V inverter.Suggestion 2: Presumably your code runs on a microcontroller of some kind? Run the 50 Hz code but connect to a 60 Hz mains supply and feed the microcontroller's clock input from a signal generator running at 6/5 your normal clock speed. So if your micro is designed for a 10 MHz clock then run it at 12 MHz and your 50Hz code should work with 60 Hz mains.

author: kripton2035
author_rank: Super Contributor
timestamp: July 24, 2014, 10:03:38 am
content: use this frequency - voltage converterdave reviewed it some times ago, inside a bank atm if I remember good.

author: KJDS
author_rank: Super Contributor
timestamp: July 24, 2014, 10:07:50 am
content: Doing the qual testing of my first ever product, some 20+ years ago, we used a huge* valve amp and a functin generator.That amp stood about 10 feet tall (3m) and was capable of producing up to 500V at 10A from 44 to 500Hz.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 24, 2014, 10:45:51 am
content: If you're doing phase-angle dimming you will need something that produces a reasonable sinewave, so cheap inverters are out.A customer of mine uses a UPS to test 60hz stuff - not sure of make/model.I've used audio amp + transformer in the past - certainly the cheapest solution for a 1-off requirement if you have the stuff lying around

author: qno
author_rank: Frequent Contributor
timestamp: July 24, 2014, 11:15:08 am
content: Get yourself an audio amplfier of 20-40 watts and a 12 to 230 Volt transformer.Get an sinus oscilator adjustable from 50-60 Hz.Any bench function gen can do that.Feed the sinus of 50 or 60 Hz about 1Vpp into the audio amp.Connect audio amp to 12V windings of the transformer.Set volume of the amp so you get 230 volt rms on the transformer output.When loading the transformer keep an eye on the output of the audio ampso yo do not overload it.

author: Zero999
author_rank: Super Contributor
timestamp: July 24, 2014, 08:13:56 pm
content: Quote from: richard.cs on July 24, 2014, 08:51:58 amBetter still, get the code to measure the mains frequency, so it'll work regardless of whether it's powered from 50Hz or 60Hz and slightly above and below.

author: kingofkya
author_rank: Regular Contributor
timestamp: July 25, 2014, 06:00:19 am
content: SO i guess there is not really a correct tool:)I think i will just fake it and feed my zerocross detection with a function generator. Found a SIMPSON 420 function generator on ebay for $60 so i am just goign to use that and make sure my leading edge pulse matches up correctly.Thanks for the opinions. Even if there wasn't a "Correct tool" for the job.I also look up theseshttp://en.wikipedia.org/wiki/Variable-frequency_drivebut seams most of them run a modified sine wave so not really going to be helpfully to me.Also if your wondering what I am working on :http://hackaday.io/project/1092-Raptor12-AC-light-controllerI don't really expect a non us person to use it. Kinda over thinking it but oh well.From what i read most people in 220v country have 24-48v transformers on consumer light strings, because of the increased risk, so likely a non issue.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: July 26, 2014, 01:27:55 pm
content: Quote from: kingofkya on July 25, 2014, 06:00:19 amThere are plenty of correct tools, e.g.http://www.telonic.co.uk/products/categories/acps/variable_frequency_converters_single_phase.aspThey're just a lot more expensive than hooking up an audio amp, though I'm sure you can rent one