Is there any correlation between a coil's effect on voltage & its effect on frequency?
e.g. If a winding reduces 240v to 12v what will be its effect on an audio signal.
e.g. If a winding reduces 240v to 12v what will be its effect on an audio signal.
An inductor has an impedance that is proportional to frequency.
The higher the frequency, the higher the impedance.
The higher the frequency, the higher the impedance.
I'm asking if a transformer from a power supply can be used as a low-pass filter.
Many standard 50/60 Hz power transformers have less than 1kHz bandwidth, and the cores are rather lossy.
But the voltage ratio depends directly on the relative number of winding turns of each, and is not intended to vary with frequency.
There are many specialized transformers used for just for audio signals, in crossovers, mixers, amplifiers, etc.
But the voltage ratio depends directly on the relative number of winding turns of each, and is not intended to vary with frequency.
There are many specialized transformers used for just for audio signals, in crossovers, mixers, amplifiers, etc.
I have no idea. I have 240v / 12v and 240v / 9v.
It's a very long story. I'm just trying to make a very temporary low pass filter.
The connections can be made to one winding of the transformer to make it an inductor.
However, as rayma implies, using a transformer winding as an inductor may not be very efficient.
Usiing a step down power transfomer without knowing it's inductance is going to be a guess at best. if you wish to use it as a filter element. Plenty of multi-meters have the ability to read inductnace. Having access ot one is going to be a good start. From there you coud download Win-Isd (or any other crossover program and mode/ the LP filter with your load of choice.
It may be useful for you to know that the low voltage winding will have a smaller inductance than the high voltage winding.
I'd pick on the windings individually and plot them over the audio band, determine self resonance, inductance..
A transformer is basically made of at least 2 inductors, one for primary other for secondary (they can be joined internally if it is an autotransformer so no galvanic isolation).
What enables these 2 inductors to act as a transformer is the mutual inductance, which is achieved by each inductor sharing the same magnetic path.
If you leave the leads of one inductor open (secondary or primary), you can use the other inductor as a regular inductor with an iron core.
Things to check/measure for your needs:
-Inductance you need and what is available in the coils of your transformers (can be either primary or secondary)
-Coil resistance - need to see if this is ok for your application as low pass filter
-Maximum current regarding power dissipation (check original transfomer maximum current for primary/sencondary)
-Maximum current at a certain frequency to make sure you do not reach saturation. The higher the current and the lower the frequency combined will lead to saturation at a certain point.
-Maximum frequency you need - these transformers we made to operate at 50/60Hz as a transformer. It doesn't mean the inductors cannot be used in higher frequencies with some limitations (spurious capacitance, for example) - even the transformer works with higher frequencies. I would say that up to some kHz it will work. I've done that couple of times.
Typically:
-Primary (240V) will have more inductance, more resistance and less current capacity
-Secondary (12V/9V) will have less inductance, less resistance and more current capacity
What enables these 2 inductors to act as a transformer is the mutual inductance, which is achieved by each inductor sharing the same magnetic path.
If you leave the leads of one inductor open (secondary or primary), you can use the other inductor as a regular inductor with an iron core.
Things to check/measure for your needs:
-Inductance you need and what is available in the coils of your transformers (can be either primary or secondary)
-Coil resistance - need to see if this is ok for your application as low pass filter
-Maximum current regarding power dissipation (check original transfomer maximum current for primary/sencondary)
-Maximum current at a certain frequency to make sure you do not reach saturation. The higher the current and the lower the frequency combined will lead to saturation at a certain point.
-Maximum frequency you need - these transformers we made to operate at 50/60Hz as a transformer. It doesn't mean the inductors cannot be used in higher frequencies with some limitations (spurious capacitance, for example) - even the transformer works with higher frequencies. I would say that up to some kHz it will work. I've done that couple of times.
Typically:
-Primary (240V) will have more inductance, more resistance and less current capacity
-Secondary (12V/9V) will have less inductance, less resistance and more current capacity
Transformers used as inductors may distort a lot, as the cores are usually ungapped. Old-fashioned EI transformers are probably better in that respect than toroidal transformers.
When you use, for example, the 12 V winding as an inductor, keep in mind that an almost 20 times as large voltage will occur across the 240 V primary winding. Be careful!
When you use, for example, the 12 V winding as an inductor, keep in mind that an almost 20 times as large voltage will occur across the 240 V primary winding. Be careful!
Clearly this is getting too complicated. Perfection has become the enemy of progress. Obviously there is no clear correlation between the step down & the value in mH.
I was evicted. All my belongings, sound-system, tools went to storage.
There an error in the paperwork.
I was stuck with no music.
Had micro system but no bass.
Made sub out of dumpster parts.
Wanted to make low-pass filter out of spares.
Should never have asked the question.
Suck it &7 see, right?
I was evicted. All my belongings, sound-system, tools went to storage.
There an error in the paperwork.
I was stuck with no music.
Had micro system but no bass.
Made sub out of dumpster parts.
Wanted to make low-pass filter out of spares.
Should never have asked the question.
Suck it &7 see, right?
Exactly!
Connect the 9 V winding in series with your loudspeaker and hear for yourself what frequencies are reproduced.
I reckon the inductance of the 9 V winding will result in a crossover point that is too low for your requirements.
Experimenting with a 12V transformer secondary winding, I think it should be fine.
Low-pass-filter-calculator
Keep in mind that a transformer rated for 2A output current can safely operate up to 32W @ 8Ω and 16Watt @ 4Ω. As @MarcelvdG pointed out, make sure to cover the primary winding wires with electrical tape just to be safe!