Hum out of transformer

borgbob

Hi All-

We have built DC--> AC power set up for the small Coffee van. Set up is: Deep cycle 110ah battery, 1000 W inverter + battery charger. All working fine, however, the inverter is "modified sine wave" as supposed to "pure sine wave" so small cash register's transformer is producing humming noise.

I know it's a common problem because of the choppy waves, but is there anything, like plug/socket that can be put between the wall socket and the register's plug that will stabilize the flow and eliminate the hum?

PS. I know that pure sine wave inverter would remedy it, but at the moment that is not an option as 1000 W pure sine inverters are too expensive, (need minimum 1000 W). For the record, cash register draws very little, 230 V, 30 W which is ~ 0.13 A.

Thanks in advance!

DublinDilbert

borgbob wrote: »

Hi All-

We have built DC--> AC power set up for the small Coffee van. Set up is: Deep cycle 110ah battery, 1000 W inverter + battery charger. All working fine, however, the inverter is "modified sine wave" as supposed to "pure sine wave" so small cash register's transformer is producing humming noise.

I know it's a common problem because of the choppy waves, but is there anything, like plug/socket that can be put between the wall socket and the register's plug that will stabilize the flow and eliminate the hum?

PS. I know that pure sine wave inverter would remedy it, but at the moment that is not an option as 1000 W pure sine inverters are too expensive, (need minimum 1000 W). For the record, cash register draws very little, 230 V, 30 W which is ~ 0.13 A.

Thanks in advance!

Hi, is the Hum coming from the register itself?

I would modify the register and get it to run off 12V, the main PSU in the register probably takes the mains down to 12V anyway.

You could try fit an RC filter on the supply to the resister which would take away a few of the harmonics, but you won't be able to filter it that much and still delivery much power.

ted1

As above ir you could try fitting a small ups. There about 60 quid.

borgbob

Thanks guys, I'll try that.