to convert 50hz to 60hz

[Geoff_T]

Hi

Why do you need to change the frequency? A lot of digital equipment will use switch mode supplies that couldn't care less about the frequency...

[r0ck1r0ck2]

thanks for replying mr. t.

there are several devices such as these Event Asp8's and my LynxAurora16 that say they require 60hz..

after a tiny bit of reading, it seems that the higher voltages (around 250 to 300watts)
required (by their power transformers?) are wired for 60hz specifically..

quick aside, my english is really suffering no?

[dementedchord]

while some power trannies can get a bit hot at 50hz... for the most part it's no big deal... hasn't been since the demise of synchronous motors.... got any of those in your rig????

[Matt Syson]

Hi
IF 60Hz really is needed (and it probably isn't) then a good quality UPS ONLINE supply intended for the American market may be an option. Having one with a CLEAN 60Hz output is essential.
As a possibility, and slightly 'off the wall' is to use a cheap power amp say 300 watts per channel (8 ohm) intended, operated in mono 'bridge' mode and fed with a 60Hz tone (sinewave). Not very efficient but certainly a clean signal and OK for a couple of hundred watts. Have to work out what the required 'voltage' level would be but 110 volts is quite achievable this way. Or a power amp and a transformer on it's output to step it up a bit.
Matt S

[tINY]

Let's see...

110v RMS into 8 ohms is about 1500 W. Leaving some headroom for the extra current draw at the peaks, you probably want about a 2000W amp for the sine wave trick. - Unless you want to add a step-up transformer to the outputs (which might be a good idea).

Remember that equipment MFGs (especially in the US) give all kinds of warnings and conservative specs to keep from having to fix something under waranty that is used in an unusual manner.



-tINY

[Matt Syson]

Hi
I wasn't explaining what I meant very well. An amp rated to give about 400 watts into 8 ohms would give about 55 volts RMS. Used in 'bridge ' mode would give 110.
As I said it is a little 'off the wall' but with so many 'cheap' stereo amps around it might be viable. It depends how much power is actually wanted. I would be a bit suprised if the gear could not cope with 50Hz anyway.
You can buy powerful 100Volt line amps for PA installation which would do the job, or use a transformer on a power amp.
Matt S

[r0ck1r0ck2]

dearest babies..

i think i'm a bit confused here..
you're suggesting a power amp...as in AC power...or an audio amp for my passive Asp8's?

because they're active..

again...my head is swimming with confusion after walking around to electronic supply stores and trying to explain in my shit spainish that i want to convert 50hertizos to 60..

need me some 60hz 120v AC...

thanks again lads..

[Matt Syson]

Sorry, we were digressing.
FIRST, call the manufacturers of the various pieces of equipment and ask whether they actually HAVE to be supplied at 60Hz.
IF you MUST have 60Hz then there are a couple of ways of 'making' it.
You need to say how much power is needed at 120Volts (100Watts, 500 Watts or ?). If it is a couple of hundred watts max then it is relatively easy but otherwise go with finding an online power converter. Please 'google' and see what you come up with and say you want 50Hz at presumably 220-230Volts in and 120Volts 60 Hz out. This will cost MONEY unless you can import something from USA, which may be a decent option as I presume they will have converters that will take 50 - 60Hz, rectify then generate 60Hz 120 Volts from it. It will need to be a specific unit that is always convertingn not the cheaper 'standby' boxes that usually pass the supply through but then switchover FAST to maintain an output. It will also need to be well filtered to get rid of harmonics.
Using a power amp was simply a suggestion in that they are relatively cheap and could provide a few hundred watts at low distortion. May be cheaper than a decent converter.
Or sell the stuff and get something decent that is not so fussy!
Matt S

[r0ck1r0ck2]

lovely..thank you very much..i'll re-read that post when i'm not outofmymind tired/drunk

thanks again..

[David Kulka]

I agree with Matt's comment -- in my opinion there are very few pieces of gear that would would have trouble with 50 Hz. The power transformer would be the only real concern so to check a piece your unsure of you could just run it for a while and touch the transformer. If it's too hot to keep your finger on, it's too hot. If it isn't, you're ok.

[svart]

easy:

50hz->rectify->chop->derive +/- DC rails-> use multistep MOSFET PWMing to chop rails into a semi-sine wave@60hz->filter-> 60hz output.

Like I said simple.

[samwise]

Originally Posted by r0ck1r0ck2

anyone have any advice on this...

got a banging voltage convertor..

now i'm faced with converting the cycles per second..

for these eventasp8's and this lynx aurora..probably a few other things as well..

funny..the apogee rosetta will have no troubles with the hz change whatsoever...
as does my old gibson skylark..

so a 40+ yr old device will handle the hz better than a 4yr old device..

hrmph..

A quick word about what this is about.

In conventional power supplies, the mains is rectified (that means the negative parts of the main cycle are flipped over to become positive). This gives 50 or 60 positive pulses per second. These pulses are used to charge up capacitors that store the charge between top ups. If you put a 'scope on the capacitor, you will see a sawtooth waveform that shows the top of the pulse, then the voltage diminishing as the current is drawn by the unit.

If the PSU is a wallwart, it might have only the transformer in it. Or it might have the rectifier and capacitors as well. Or it might even have a voltage stabiliser in it that removes the sawtooth ripple before it gets into the following gear.

Two different problems can arise in changing from 60Hz to 50Hz.

1 The number of pulses per second decreases. If the gear draws constant current, then the transformer must deliver more current on each 50Hz pulse than it would at 60Hz. Under-rated transformers can get hot coping with this. You can tell but measuring the temperature on the transformer if you are going to get a problem. Your finger should do. But don't kill yourself in the process by touching the mains power terminals.

2 On the capacitor, the voltage dip will get deeper at the bottom of each cycle, since current is flowing out of it for longer. This increases the ripple. The result can be that it becomes more audible. Your ears can test for that.

The capacitor can get stressed. You nose will tell you that one, though your finger might give a warning. There might also be a resistor in the way somewhere that gets a bit warmer than designed for.

The stabilising circuit that follows might find that the voltage coming in drops below the voltage planned to go out. So ripple appears on the output of the stabilised supply. While this won't usually break the gear, the resulting noise might want to make you bin it.

SUMMARY

The ear test will give you instant feedback. The finger test needs a few minutes for heat to build up, but power can be removed before self-destruction begins.

Try these to see if you really need to do anything to make the gear run at 50Hz.fuuck

[ezrecords]

a ver rock1 rock2 el que la frecuencia de red sea de 50 hz o de 60 hz solo te va a afectar en un pequeño porcentaje en el rizado de la tension de continua que alimenta a toda tu circuiteria. se supone que cuanto menos rizado mas pura es la señal de continua que lo alimenta y mas estable frente a ruido y oscilaciones es tu maquina, aun asi normalmente se suele colocar pequeños condesandores ceramicos e incluso a veces electroliticos junto a las patitas de los componentes que se alimentan con esta continua, si lo pones en pararelo y hacia masa con las patitas formaras un filtro paso bajo yendose el posible rizado hacia masa.
supongo que tendras una maquina diseñada en estados unidos con unos condensadores electroliticos de la fuente diseñados para un determinado rizado con una frecuencia de 60 hz, bien ahora al tener una menor frecuencia ( 50 Hz ) las caracteristicas del rizado variaran, pero no en gran medida, aun asi si te quedas mas a gusto lo que puedes hacer es variar el valor de los condensadores electroliticos de la fuente. estos condensadores son muy faciles de reconocer en un equipo puesto que suelen ser los mas gordos que lleva el equipo.
mi consejo particular es que no te ralles con este asunto y disfrutes de tu equipo a 50 hz o a 60 hz, un saludo

[svart]

Samwise, I want to add some more information to some of your statements:

1 The number of pulses per second decreases. If the gear draws constant current, then the transformer must deliver more current on each 50Hz pulse than it would at 60Hz. Under-rated transformers can get hot coping with this. You can tell but measuring the temperature on the transformer if you are going to get a problem. Your finger should do. But don't kill yourself in the process by touching the mains power terminals.

The number of pulses diminishes but the heat is not specifically from the current draw itself, it's from the error in the change of resonance. The heat is from the alternating current not changing polarity as fast as the core was designed to be operated at. This causes the flux density to be different resulting in much higher primary currents as the core is saturated for longer periods of time, not specifically the current draw itself as the tranny should have been overspec'd for safety in the first place. However as the tranny becomes inefficient the current draw does become more signifigant and a downwards spiral ensues.

2 On the capacitor, the voltage dip will get deeper at the bottom of each cycle, since current is flowing out of it for longer. This increases the ripple. The result can be that it becomes more audible. Your ears can test for that.

Capcitors rarely care how long they source current for even though they are rated for ripple vs. time. They DO care how much current they source at any given time. Large alternating current draws with insufficient bulk capacitance cause large scale heating of the caps. Again the problem is not with the current draw of the device per se, the problems start arise as the transformer becomes more and more inefficient as it's core is flux soaked and refuses to source current which would normally supply both the caps and load. As the load draws current from the caps and they can no longer supply currents needed to keep the rail stiff, your situation of ripple increase becomes reality. So it's not so much the capacitor's fault as it can only supply peak currents for a cycle or two after the tranny starts to tank out and then the DC levels start to fluctuate downwards as the core can no longer support the current draw. So in short, they won't be doing any more work than they would if the device was working normally because the source current is diminished and it cannot support the load or charging the caps fully. Now if the caps were repeatedly charged fully and discharged fully you could stress them out to the point of failure but this can't be the case with a saturated transformer.

The stabilising circuit that follows might find that the voltage coming in drops below the voltage planned to go out. So ripple appears on the output of the stabilised supply. While this won't usually break the gear,

Vregs do get sloppy when their inputs fall below the outputs, but this can only happen for a very short period of time like when the output of the Vreg has signifigant bulk capacitance to keep the voltage rail supported in lieu of the proper current source. Since I and V have a relationship, once the current droops, so does the voltage(in a constant draw relationship..) and while the regulator starts to crap itself, you are likely to begin having other serious issues with the following circuits that overshadow the ripple problems somewhat. Lets say you are using +-15v rails on an opamp and your signal level is set in such a way that you are getting +-10v PP on the output (the rest is waste heat, circuit limitations etc) and suddenly your transformer saturates and can not supply the necessary currents, your rails now drop to +-10v under load and your output level now drops to +-5v. Your input signal is now clipping(without being turned down) which would overshadow your ripple signifigantly. Your clipping is now railing your output devices which are causing shootthoughs and further demand more currents to slew themselves off of the rails. Again a downwards spiral.

Now granted this is for most older gear as more and more manufacturers are grossly overdesigning their power transformers and utilizing them for both 50 and 60 hz. So in the case of a tranny that refuses to work at a different freq, I would tend to just buy a new one spec'd for both and forget about it.

[mbrebes]

Usually the problem with power supplies is going from 60Hz to 50 Hz, because of the transformer not being able to handle the lower frequency. You shouldn't really have a problem going from 50 to 60Hz, since it is easier on the transformer and other circuit parts like capacitors.