How can I get a 60Hz supply?

[crusher19860138]

Hello,

I have some American equipment, clocks, clock/radios that rely on the 60Hz supply frequency for their timing. Whilst I can obtain a 117-120 volt supply easy enough, how can I get it at 60Hz? The clocks in particular are running about 20% slower on 50Hz,and so do not keep time.

[twocvbloke]

I think the easiest way of getting 60hz is to have your own generator, cos 50hz is all you'll get here in the UK from the mains supply...

One option is of course the generator, with a 120v 60hz output, which of course will be nothing short of a nuisance. The other option I can think of is a 12v to 120v Inverter, full sine wave (expensive) would be best for electromechanical devices, but the issue is that you need a big enough 12v supply and of course the money to buy such an inverter. A Quasi-sinewave may work, but they've been known to mess about with electromechanical timers and stuff on things like washing machines, so may not work so well...

Noting that you're in Stourbridge, there may be some narrowboat owners there who can explain inverters, wiring, charging and 12v stuff and whatnot better than I can, though they usually deal with 240v, the same principal applies...

[crusher19860138]

Thanks for that.

I do understand some inverters can be adapted to give out 60Hz, I have also seen on eBay 120v/60hz inverters. My experience of 240 volt inverters is that most electronic equipment does not like them, they seem very 'noisy' when powering up sound equipment and by that I mean the inverter gives interference to the audio, especially radios.

Clocks also make a strange buzzing sound when powered up by inverters, so I think a generator may be the way to go. The only other option I have yet to explore is a directly coupled motor-alternator set, whereby a 240V/50Hz motor directly drives through a shaft a 120v/60Hz alternator, giving a clean AC output. Apparently these arrangements are used in industry, not sure of the cost though.

[Billy T]

One concept I have toyed with myself is an audio amplifier driven by a 60Hz sinewave, which is not difficult to generate and naturally will be a low level signal. Clocks require very little power and quite powerful amplifiers can be obtained for peanuts from second-hand sources.

With the amp driving into a filament trasformer secondary, with a bit of luck and adjustment you should be able to generate 90-110v at 60Hz on what was the primary winding. Clocks are generally not voltage senstive until you get well below 200 volts either, I have had one 230/240 volt clock running on an isolated 200 volt supply made from back to back 'odd-job' transformers (because it was not possible to fit a safety ground) so a 100-110 volt supply should be easy to generate, and at minimal cost. A small mono amp module might be a good start.

Cheers

Billy

[julie_m]

Our own Kat Manton has used a PA amplifier with 100V line output, fed from a signal generator, to power equipment.

A transformer will naturally tend to knock the worst edges off a square wave, and clocks don't need much juice, so a (simple homebrew) single-stage inverter would probably be reasonable for powering a clock.

[steve102]

The following link provides a solution for 60Hz clocks
http://sound.westhost.com/clocks/freq-changer.html

[Chiltern]

Google 'Jukebox frequency converter'.

you will find that there are suppliers of 50-60c/s converters. Ideal for an expensive jukebox, especially for those designs that would require a change of gearing (rather than pulleys/belts and idlers) to get the turntable speed correct. not cheap, but they are available.

Alan

[Mike Phelan]

I'd go for Steve's link.

[Lucien Nunes]

Small inverters come in two flavours - 'quasi sine' which is a 3-step waveform and not really sinusoidal at all, and 'true sine' which is what it says. A true sine wave 60Hz inverter will give good enough quality power for any ordinary electronic / clock / player motor application. They are a bit more expensive than the quasi but still viable for this sort of job. They can be powered from a basic 12V DC supply, and whilst it's theoretically possible to mod them to cut out the 12V step and just run the inverter from a mains transformer, it's not really worth the effort.

The ordinary jukebox converter is a handy thing, that would be the most compact and straightforward as it's mains in - mains out, but AFAIK they are all non-sinusoidal output as they are intended only for shaded pole player motors that run OK on that waveform.

Lucien

[Mr Moose]

Hello,
The output frequency from an alternator depends on the number of poles it has and the speed.
If you couple a 50Hz motor to a 60Hz alternator with the same number of poles then you will get 50Hz out. To get 60Hz out you need to put 5:6 ratio gearing between the motor and the alternator to increase the speed of the alternator. (The frequency would be slightly less than 60Hz as there would be some slippage in the motor)
If the number of poles differs then you would have to adjust the gearing to allow for this.
You could simply increase the speed of a 50Hz alternator to give 60Hz but this would probably increase the voltage as well although this could be overcome with a suitable autotransformer.
Yours, Richard

[Herald1360]

Whatever you use, if you want clocks to be accurate, the 60Hz will need to be at least derived from a crystal source or perhaps by direct gearing between a 50Hz synchronous motor and a 60Hz generator.

If you don't need silly amounts of power, a divided down clock crystal providing 60Hz sine wave drive to an audio amplifier with the appropriate ratio step up transformer on its output would probably be the cheapest way to go.

[Jamie-Skinner]

Yeah Steve's link sound good... We had one but not from that site and it did the job!!

[dmaillard]

This link may also help,

http://www.kakopa.com/60HzConverter/


Regards
David

[dave cox]

I think the "kakopa" convertor, posted by David, whilst be laudibly simple, will not be suitable for a clock. The time reference is a 555 timer device and will drift far too much. The circuit described on the ESP website, posted by Steve, looks like exactly the thing for clocks. I should add that Elliott (of ESP) has a very good reputation for projects and designs.

dc

[ppppenguin]

Another vote for the ESP converter but I'd be tempted to replace the bandpass filter either with analogue lowpass or one of the switched capacitor type of filter chips. Either of these solutions should give low enough distortion without adjustment.

[dave cox]

Ooop, I should have course said Rod Elliott, of ESP

[davegsm82]

How about 2 little record deck induction motors, 1x UK 50Hz, 1x intended for US 60Hz. Connect shafts directly, use rubber tubing or something, put a suitable capacitor across the 60Hz one and apply mains to the 50Hz one.

Should provide an approximate 60Hz signal, which can then be trimmed by the cap connected across it to affect 'slip'.

Or, if you want to go solid state, use a PIC and an SA8282 3 phase (in single phase mode) PWM sinewave generator + some small scale output circuitry.

Dave.

[julie_m]

Won't work. You need magnets for a generator -- either permanent or energised. The only AC motors with permanent magnets are synchronous ones (as used in clocks; and, because they stall nicely when fed DC, central heating valves). Most record deck motors are shaded-pole, and rely on a current induced in the armature to magnetise it.

[davegsm82]

Hi ajs_derby

Thats the point of the capacitor on the output terminals, generating using shaded poles is possible, it relies on the tiniest magnetic flux to 'self excite' and start generating.

I'll be honest with you, I don't 100% understand the physics behind it, but I do know i've tried it and it does work, just needs to be going fast enough before it springs into life.

Dave.

[Mike Phelan]

Induction motors, shaded pole or other ways of starting them, do not run at the supply frequency. There has to be slip to induce a current in the rotor, so we get less than 1500 RPM for a four-pole motor; typically something like 1450.

It's the rotor that would need to be magnetised, not the stator. Both of them are soft iron, magnetic but not magnetisable.