UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > General Vintage Technology Discussions

Notices

General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc.

Reply
 
Thread Tools
Old 11th Jul 2019, 5:26 pm   #1
Hunts smoothing bomb
Octode
 
Hunts smoothing bomb's Avatar
 
Join Date: Oct 2005
Location: Wimborne, Dorset, UK.
Posts: 1,360
Default American 60Hz clock - Will it run on pulsed DC?

Hi all,

Excuse me if I'm being ignorant here but I wanted your collective opinion, first I'll set the situation...

I am currently looking at an american clock radio for somebody, it's made by Commodore and is a 117v valve set, now the 117v part isn't difficult as I have a suitable transformer that will fit inside the set as there is lots of room, the issue I do have though is with the clock itself as it runs way too slow on 50Hz
Now, my question is this.. If I pulsed DC into the clock winding (also designed for 117vac) at 60Hz would it work? and secondly and most importantly could I do it with a much lower voltage?

Answers on a postcard please!!

Cheers
__________________
Lee
Hunts smoothing bomb is offline   Reply With Quote
Old 11th Jul 2019, 7:15 pm   #2
Maarten
Nonode
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 2,504
Default Re: American 60Hz clock - Will it run on pulsed DC?

Pulsed DC seems like a bad idea. You could probably build a small sine generator and use it to drive a power transformer in reverse to obtain the right voltage.
Maarten is offline   Reply With Quote
Old 11th Jul 2019, 9:00 pm   #3
broadgage
Octode
 
Join Date: Jan 2010
Location: North Somerset, UK.
Posts: 1,334
Default Re: American 60Hz clock - Will it run on pulsed DC?

Remember also that the inductive impedance of the clock motor winding will be reduced at a lower frequency.
You may therefore need to reduce the voltage to perhaps 100v/110 volts rather than the designed 117/120 volts.
broadgage is offline   Reply With Quote
Old 12th Jul 2019, 1:42 am   #4
Argus25
Nonode
 
Argus25's Avatar
 
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,254
Default Re: American 60Hz clock - Will it run on pulsed DC?

You can order these with a UK input plug and get your 60Hz 110V power this way:

https://www.kccscientific.com/product/1930/

I have used other solutions too. Often the rotor in the clock is a separate item, available in both 50 and 60 Hz versions, if you are lucky you might find one in a clock on ebay.

In one case for one of my 110V 60 Hz clocks, I disassembled the rotor assembly and Ken Reindel machined a new gear for me (near the output shaft) to alter the ratio to correct it for 50Hz use. He is a master clockmaker:

http://www.kensclockclinic.com
Argus25 is online now   Reply With Quote
Old 12th Jul 2019, 7:32 am   #5
TrevorG3VLF
Octode
 
Join Date: Apr 2011
Location: Matlock, Derbyshire, UK.
Posts: 1,238
Default Re: American 60Hz clock - Will it run on pulsed DC?

I have seen circuits of a 300Hz oscillator, phase locked to the mains and then this is divided by 5 to get 60Hz or 6 to get 50Hz. This will then need to be amplified to get a suitable supply for the clock.
Pulsed DC could work if the DC was blocked and only the pulses passed but you will need an accurate frequency source. There are invertor circuits to give out AC.
This is a nice little project using CMOS or a microprocessor.
TrevorG3VLF is offline   Reply With Quote
Old 12th Jul 2019, 8:02 am   #6
Nickthedentist
Dekatron
 
Nickthedentist's Avatar
 
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 14,312
Default Re: American 60Hz clock - Will it run on pulsed DC?

Similar gadget to the one mentioned by Hugo here:
http://www.electric-clocks.co.uk/Fre...cyconvert.html
Nickthedentist is online now   Reply With Quote
Old 12th Jul 2019, 8:10 am   #7
steve102
Triode
 
Join Date: Jan 2008
Location: Derby, Derbyshire, UK.
Posts: 13
Default Re: American 60Hz clock - Will it run on pulsed DC?

I use one of these converters to run a 60Hz Telechron clock from 50Hz UK mains:
http://www.electric-clocks.co.uk/Fre...cyconvert.html
steve102 is offline   Reply With Quote
Old 12th Jul 2019, 8:58 am   #8
julie_m
Dekatron
 
Join Date: May 2008
Location: Derby, UK.
Posts: 7,327
Default Re: American 60Hz clock - Will it run on pulsed DC?

There is no need to worry about the waveform, just as long as it is symmetrical (for the sake of the permanent-magnet armature). A crystal oscillator and suitable divider chain will do fine; the division should ensure symmetry. Use the Q and Q' outputs from your last flip-flop to drive the gates of a pair of MOSFETs, one drain to each end of the centre-tapped secondary winding of a suitable transformer, the tap to the unregulated supply and the primary to the clock motor.

Small transformers tend to have lousy regulation, so one rated for 18-0-18V from a 230V supply probably will give about the right output with a 12V DC supply. The clock should still run from a reduced voltage.
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments.
julie_m is offline   Reply With Quote
Old 12th Jul 2019, 9:34 am   #9
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 4,187
Default Re: American 60Hz clock - Will it run on pulsed DC?

Quote:
Originally Posted by TrevorG3VLF View Post
I have seen circuits of a 300Hz oscillator, phase locked to the mains and then this is divided by 5 to get 60Hz or 6 to get 50Hz. This will then need to be amplified to get a suitable supply for the clock.
Pulsed DC could work if the DC was blocked and only the pulses passed but you will need an accurate frequency source. There are invertor circuits to give out AC.
This is a nice little project using CMOS or a microprocessor.
http://sound.whsites.net/clocks/freq-changer.html

Quite complicated though.
PJL is offline   Reply With Quote
Old 12th Jul 2019, 10:03 am   #10
IanBland
Hexode
 
Join Date: May 2015
Location: Northampton, Northants, UK.
Posts: 294
Default Re: American 60Hz clock - Will it run on pulsed DC?

I would be inclined to use a microcontroller as a pseudo phase locked loop, one of the PICs with a zero crossing detector would be ideal.
IanBland is offline   Reply With Quote
Old 12th Jul 2019, 10:44 am   #11
Maarten
Nonode
 
Join Date: Dec 2007
Location: Haarlem, Netherlands
Posts: 2,504
Default Re: American 60Hz clock - Will it run on pulsed DC?

When going the non-sinusoidal way, the RMS voltage would be important to get right, too.
Maarten is offline   Reply With Quote
Old 12th Jul 2019, 11:06 am   #12
IanBland
Hexode
 
Join Date: May 2015
Location: Northampton, Northants, UK.
Posts: 294
Default Re: American 60Hz clock - Will it run on pulsed DC?

Well, at a fixed, known frequency, a square wave can be made into a very good approximation of a sine wave (better than anything that comes off the mains, heh) with a simple RC filter. Then step it back up with a Class A or AB output stage... ooh, this is actually getting quite complicated isn't it?
IanBland is offline   Reply With Quote
Old 12th Jul 2019, 3:30 pm   #13
merlinmaxwell
Dekatron
 
merlinmaxwell's Avatar
 
Join Date: Jul 2008
Location: Maidenhead, Berkshire, UK.
Posts: 8,412
Default Re: American 60Hz clock - Will it run on pulsed DC?

Quote:
with a simple RC filter.
A square wave into an inductor would do the same thing. The inductor being the clock winding.
__________________
Cats have staff, it's dogs that have owners.
merlinmaxwell is offline   Reply With Quote
Old 15th Jul 2019, 2:17 pm   #14
Hunts smoothing bomb
Octode
 
Hunts smoothing bomb's Avatar
 
Join Date: Oct 2005
Location: Wimborne, Dorset, UK.
Posts: 1,360
Default Re: American 60Hz clock - Will it run on pulsed DC?

Hi guys,

Thanks for all the replies, I'm unsure yet which way to go regarding this, to buy a ready made unit or to construct from scratch (I prefer the latter I think)

Still, plenty of food for thought.

Thanks again!


Cheers
__________________
Lee
Hunts smoothing bomb is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 1:04 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Copyright ©2002 - 2019, Paul Stenning.