AC Powersupply

We need to create a piece of test equipment that can produce 240V 50Hz with a superimposed 5-20 V ripple at 1050Hz. We have the source signal but it can only achieve 30V we need to step this up to 240V has anyone heard of a transformer that is say 10(15)-1 ration with a broad frequency acceptance 50HZ to 1050HZ.

Alternatively given we have plenty of 50Hz E and I transformers we potentially could split the signals and put the 1050 Hz through a 1000Hz 30 VA 10(15)-1 ratio transformer with a high secondary impedance and combine back with the 50HZ, I am struggling to find this specification. Audio transformers have the range and ratio but not the power handling. Any feedback would be most welcome

Hello @GroupSYS,

This is my understanding of your circuit. This assumes that we have 50 Hz mains and are using a transformer to inject the 1050 Hz signal.

Locating specifications for a transformer in this application will be difficult. Your 30 VA requirement may be met using a 100 VA 1 to 1 isolation transformer. I suspect core saturation is the greatest problem with this design. Recall that saturation is a function of applied voltage and frequency where our problems first show up with high voltage and low frequencies.

Note that the transformer reflects the full load current back into the 5-20 VAC source as shown in this image. Consequently, the 5 to 20 VC source must have a low output impedance. This shouldn’t be too difficult to meet with an audio amplifier. However, depending on the nature of the load, there may be complications.

This sound like an interesting project. Please let us know how you solved the problem.

Best wishes,



Thanks for your response and all your hard work, I have solved the problem in a rather an orthodox way.

I used an high powered Class D amplifier, I cast an Audio Wav file of the frequency(s) I wanted, with the volume at max I could achive around 15 V RMS at the speaker terminals and a perfect Sinusdiol Wave.

Through hours of trial and error I found a combination of E and I, 50Hz Transformers, could step up the speaker terminasls (15V) to 240V the Sine wave remained intact (mostly), ironically the cheaper transformers distored the 1050Hz component less than quality transformers !

Eitherway it worked.

I now have have to find a way to measure the visual flicker !!


1 Like


Thank you for sharing, Mark @GroupSYS.