I would like to power a MIDI Synthesizer module (the Alesis NanoSynth) from a battery to allow for fully portable use.
The snag is that the synth requires 9V AC. This is currently provided by the original ‘wall wart’ power supply [marked input: 240V ~ 50Hz output: 9V ~ 0.78A 7VA]. Under no load, my multimeter reads its output as 10.1V AC.
It was suggested, and it seemed plausible, that I should just give it 12 or 13 V DC and it would be fine. However feeding from a freshly charged leisure battery, as well as a couple of different DC-DC converters, just made it howl.
I have got it to work by putting the battery DC through a regulator to provide 12.9V DC that feeds a 75W car cigarette lighter inverter into which the synth’s mains power supply is plugged. Not only is this ugly but is seems quite wasteful of battery. With the regulator, inverter and power supply under no load the battery at approx 20v is delivering 0.25 amps. Plugging in the synth increases the drain to about 0.51 amps. It would also be safer not to have 240V AC involved at all.
It seems that a pure sine wave is not required as it does seem to be quite happy running of the cheap non-sinusoidal inverter. Though the power supply might be smoothing things out a bit??
One thing I do not know is whether the 50Hz is required by the synth as some sort of ‘clock’ signal.
I was wondering if I could adapt a simple 12VDC to 220V AC inverter circuit. Such as this one: https://www.electronicshub.org/12v-dc-220v-ac-converter-circuit/ by replacing the step-up transformer with an isolating 1:1 transformer and adjusting the input voltage. I am not knowledgeable enough to be able to find centre-tapped 1:1 transformers. I only need 7VA and that circuit is claimed to be able to deliver 35W. Is that just comfortable headroom or are the MOSFETS overkill?
Another one of the many things I do not know is whether these simple circuits provide a stable frequency and voltage under varying load.
Any guidance on finding a suitable circuit would be much appreciated. I would be glad to answer any clarifying questions.
Many Thanks Graham
The snag is that the synth requires 9V AC. This is currently provided by the original ‘wall wart’ power supply [marked input: 240V ~ 50Hz output: 9V ~ 0.78A 7VA]. Under no load, my multimeter reads its output as 10.1V AC.
It was suggested, and it seemed plausible, that I should just give it 12 or 13 V DC and it would be fine. However feeding from a freshly charged leisure battery, as well as a couple of different DC-DC converters, just made it howl.
I have got it to work by putting the battery DC through a regulator to provide 12.9V DC that feeds a 75W car cigarette lighter inverter into which the synth’s mains power supply is plugged. Not only is this ugly but is seems quite wasteful of battery. With the regulator, inverter and power supply under no load the battery at approx 20v is delivering 0.25 amps. Plugging in the synth increases the drain to about 0.51 amps. It would also be safer not to have 240V AC involved at all.
It seems that a pure sine wave is not required as it does seem to be quite happy running of the cheap non-sinusoidal inverter. Though the power supply might be smoothing things out a bit??
One thing I do not know is whether the 50Hz is required by the synth as some sort of ‘clock’ signal.
I was wondering if I could adapt a simple 12VDC to 220V AC inverter circuit. Such as this one: https://www.electronicshub.org/12v-dc-220v-ac-converter-circuit/ by replacing the step-up transformer with an isolating 1:1 transformer and adjusting the input voltage. I am not knowledgeable enough to be able to find centre-tapped 1:1 transformers. I only need 7VA and that circuit is claimed to be able to deliver 35W. Is that just comfortable headroom or are the MOSFETS overkill?
Another one of the many things I do not know is whether these simple circuits provide a stable frequency and voltage under varying load.
Any guidance on finding a suitable circuit would be much appreciated. I would be glad to answer any clarifying questions.
Many Thanks Graham