Carbsandcaps
Super Member
I want to get these Jensen a12 concert series filed could speakers going so I need a power supply preferably adjustable and inexpensive. I came across these dc motor controllers for $18 each. They put out 0-170vdc and are adjustable so what could go wrong? Well as with any switching supply, they are very noisy. They make an awful high pitched squeal
My first attempt was just a 200ohm resistor to drop voltage since I don’t need all the 170v but that did nothing for the noise. I then tried a 10,000uf capacitor after the resistor which helped but still noisy.
So then I decided to try a choke in the mix. I lowered the capacitor to 4700uf, put in a pc power supply choke in a RLC configuration and it’s helped immensely. At full voltage which after the resistor is about 90v to the speaker, the noise is completely gone (although I suspect my dogs might still hear it) but at lower voltages it’s still there, although faint.
I’m wondering if I should throw in the towel on a switching supply and build my own using isolation transformers (which I have) but then I’ll have to figure out how to make it adjustable. Any thoughts on silencing a switching power supply?
My first attempt was just a 200ohm resistor to drop voltage since I don’t need all the 170v but that did nothing for the noise. I then tried a 10,000uf capacitor after the resistor which helped but still noisy.
So then I decided to try a choke in the mix. I lowered the capacitor to 4700uf, put in a pc power supply choke in a RLC configuration and it’s helped immensely. At full voltage which after the resistor is about 90v to the speaker, the noise is completely gone (although I suspect my dogs might still hear it) but at lower voltages it’s still there, although faint.
I’m wondering if I should throw in the towel on a switching supply and build my own using isolation transformers (which I have) but then I’ll have to figure out how to make it adjustable. Any thoughts on silencing a switching power supply?
