All About Circuits Forum  

Go Back   All About Circuits Forum > Electronics Forums > The Projects Forum

Notices

The Projects Forum Working on an electronics project and would like some suggestions, help or critiques? If you would like to comment or assist others with their projects, this is the place to do it.

Reply   Post New Thread
 
Thread Tools Display Modes
  #1  
Old 12-03-2008, 02:44 PM
malcolmt's Avatar
malcolmt malcolmt is offline
Junior Member
 
Join Date: Dec 2008
Posts: 12
Default Need to convert 240v 50Hz - 110v 60Hz (newbie)

Hi floks,
The title says it all,
Here in the uk our domestic supply is 240v 50Hz, I repair clocks for a living and often get asked how to run american electric clocks (110v 60Hz) in the uk, Most people assume that just buying a step down transformer will do, then wonder why their clocks run SLOW ???
I thought it about time i researched this issue and came up with a cost effective answer.
My thoughts so far are to step down transformer to 9-12v, smooth to dc, then using a 555, create 60Hz frequency to be applied to the dc then step up transformer to 110v. Current requirements would be no more than a few watts. Any and all thoughts or possible circuits would be very much apreciated.

Kind regards

Malcolm

Last edited by malcolmt; 12-03-2008 at 03:49 PM. Reason: OOPs not fast, SLOW
Reply With Quote
  #2  
Old 12-03-2008, 02:50 PM
CVMichael CVMichael is offline
Senior Member
 
Join Date: Aug 2007
Location: Canada, Toronto
Posts: 412
Default

I'm no expert in this, but it really does not make sense to make a clock that will take the AC frequency to run the timing functions of the clock.

In other words, I think that a step down transformer is what you need. If the clock runs faster, I'm pretty sure it is NOT related to the frequency of the AC...
Reply With Quote
  #3  
Old 12-03-2008, 02:58 PM
malcolmt's Avatar
malcolmt malcolmt is offline
Junior Member
 
Join Date: Dec 2008
Posts: 12
Default

[quote=CVMichael;102651]I'm no expert in this, but it really does not make sense to make a clock that will take the AC frequency to run the timing functions of the clock.

In other words, I think that a step down transformer is what you need. If the clock runs faster, I'm pretty sure it is NOT related to the frequency of the AC...[/quote

Unfortunately that is exactly what happens, The motor is "synchronous" IE gets it accuracy from the mains frequency, Thats why they run SLOW.
Malcolm

Last edited by malcolmt; 12-03-2008 at 03:50 PM. Reason: OOPS not fast, SLOW
Reply With Quote
  #4  
Old 12-03-2008, 03:08 PM
CVMichael CVMichael is offline
Senior Member
 
Join Date: Aug 2007
Location: Canada, Toronto
Posts: 412
Default

If you use a step down, then your output will be 110v - 50Hz, and if the clock takes the timing from AC, then shouldn't the clock run slower ?

Anyways, your idea might work, but I think that a 555 does not give you precise timing, because you are using capacitors to generate the frequency. You have to use something with a quartz clock.
Reply With Quote
  #5  
Old 12-03-2008, 03:11 PM
malcolmt's Avatar
malcolmt malcolmt is offline
Junior Member
 
Join Date: Dec 2008
Posts: 12
Default

Quote:
Originally Posted by CVMichael View Post
If you use a step down, then your output will be 110v - 50Hz, and if the clock takes the timing from AC, then shouldn't the clock run slower ?
OOPS !!

I am getting confused, YES you are completely correct SLOWER NOT FASTER.
Sorry, Well spotted

Malcolm
Reply With Quote
  #6  
Old 12-03-2008, 03:17 PM
SgtWookie's Avatar
SgtWookie SgtWookie is offline
Expert Member
 
Join Date: Jul 2007
Location: In the vast midwest of the USA; CST
Posts: 22,031
Default

Odd that you say they run fast; they SHOULD be running slow. Every 60 seconds they would lose 10 seconds.

Older type motor driven US clocks rely on the 60Hz frequency to keep the clock time accurate. There are also quite a few digital clocks that use the 60Hz signal as an internal clock pulse.

Sorry to inform you of this, but your plan to use a 555 timer to generate a 60Hz signal will be woefully inadequate. Even a crystal oscillator won't be good enough. You'd need a temperature compensated or oven controlled crystal oscillator to even get close.

Another possibility could be to take the 50Hz input sinewave, multiply it by 6 to get 300Hz, then divide it by 5 to get a stable 60Hz signal. This method would leave the accuracy of the output up to the power companies.
[eta]
Here's an older article from EDN on using a uC to multiply frequencies:
http://www.edn.com/article/CA45902.html

Here in the States, the 60Hz from the power grid is very accurate. I have no clue how accurate the 50Hz is in other countries.
__________________
General info:
If you have a question, please start a thread/topic. I do not provide gratis assistance via PM nor E-mail, as that would violate the intent of this Board, which is sharing knowledge ... and deprives you of other knowledgeable input.
Reply With Quote
  #7  
Old 12-03-2008, 03:35 PM
malcolmt's Avatar
malcolmt malcolmt is offline
Junior Member
 
Join Date: Dec 2008
Posts: 12
Default

Excellent reply SGTWOOKIE

Thanks for that information, the EDN article will probably be very helpful when i have read it enough times to understand it (newbie)
I am sure you will have read my apology and correction of fast/slow by the time you read this.
I was hoping this would not be too complicated an issue but it seems like it might be, however i will persevere with it as it will be useful in my business to be able to resolve the problem outside the clock hence retaining the originality of the piece. i have considered making a new stator for the motor, to run on 50Hz but as a conservator that is not really acceptable.
Reply With Quote
  #8  
Old 12-03-2008, 04:15 PM
SgtWookie's Avatar
SgtWookie SgtWookie is offline
Expert Member
 
Join Date: Jul 2007
Location: In the vast midwest of the USA; CST
Posts: 22,031
Default

Sorry my reply was so slow; there were several exchanges between the time when I started writing it to when I actually hit the post button. I was doing some research on clock multiplier circuits for you; the EDN article seemed the most promising.

Attempting to design/build a 220V 50Hz to 120V 60Hz converter is a pretty ambitious project, particularly for a beginner. The learning curve for microcontrollers tends to be somewhat steep, but this would be the best way to approach the problem.

Even then, you'd need a transformer to get the 220V 50Hz down to power the logic and controls, and another transformer that the control circuits could generate the 120v 60Hz output power, and ensure it's regulated. You'd be hard-pressed to build something suitable for under 30 Euros - even if you didnt use a custom circuit board.
__________________
General info:
If you have a question, please start a thread/topic. I do not provide gratis assistance via PM nor E-mail, as that would violate the intent of this Board, which is sharing knowledge ... and deprives you of other knowledgeable input.
Reply With Quote
  #9  
Old 12-03-2008, 04:23 PM
RiJoRI RiJoRI is offline
Senior Member
 
Join Date: Aug 2007
Location: Long Island,NY (GMT-5)
Posts: 536
Default

Chances are that any fix would cost more than a new clock! Unless they are referring to the clocks embedded in microwaves, stereos, etc. In that case, a piece of black electrical tape should do the trick by covering up the display. ;D

--Rich
Reply With Quote
  #10  
Old 12-03-2008, 04:53 PM
malcolmt's Avatar
malcolmt malcolmt is offline
Junior Member
 
Join Date: Dec 2008
Posts: 12
Default

Hi Folks
Sarge, I figure the investment is worth making as some of these clocks are antique and of surprising value. the customer may never run the clock here. if i am restoring it i want to be able to test it at the correct voltage/frequency so i can be sure it is working to spec.

Rich
Unfortunately your sugestion is incorrect, these are clocks from as far back as the 1920s/30s and are considered antique. Although many where made, Many where thrown away so they are becoming rarer, (not ridiculously so but reasonably so) There are some really cool designs especially from the thirties.

Malcolm
Reply With Quote
Reply   Post New Thread

Tags
, , , , ,


Related Site Pages
Section Title
Textbook Practical considerations of ADC circuits : Digital-analog Conversion


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to convert an 110V AV receiver to be used on 220V ? evolutionX General Electronics Chat 22 09-20-2008 10:05 AM
How to convert 340V DC to produce 220V 50Hz AC zahidislam General Electronics Chat 5 06-17-2008 01:49 PM
Getting Chinese 240V from US 110V? jstumbo General Electronics Chat 11 12-25-2006 05:44 PM

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 01:29 PM.


User-posted content, unless source quoted, is licensed under a Creative Commons Public Domain License.
Powered by vBulletin
Copyright ©2000 - 2014, vBulletin Solutions, Inc.