preenfm Forum

PreenFM => preenfm2 and preenfm3 => Topic started by: christianlukegates on January 30, 2021, 10:34:19 AM

Title: DC power adaptor- correct polarity..?
Post by: christianlukegates on January 30, 2021, 10:34:19 AM

Hi

Purchased a 7.5-9V DC power adapter. In the instructions for that adapter it gives options for setting it up with either positive or negative polarity.. which is correct for using with my FM3? or should i just stick with the USB power?

Title: Re: DC power adaptor- correct polarity..?
Post by: Xavier on January 30, 2021, 11:24:13 AM

Quote from: christianlukegates on January 30, 2021, 10:34:19 AM

Hi

Purchased a 7.5-9V DC power adapter. In the instructions for that adapter it gives options for setting it up with either positive or negative polarity.. which is correct for using with my FM3? or should i just stick with the USB power?

Hi,

Go with 9V. (7.5v will turn on the preenfm but the DAC will receive less than 5V and willl provide less output voltage).
And more important choose Center positive.
It's now written clearly on the latest PCB revision.

Xavier

Title: Re: DC power adaptor- correct polarity..?
Post by: christianlukegates on January 30, 2021, 05:14:16 PM

there actually doesnt appear to be an option for centre, only positive or negative(...?) so i will leave it. thanks for replying  :)

Title: Re: DC power adaptor- correct polarity..?
Post by: vurt on January 30, 2021, 06:54:10 PM

Quote from: christianlukegates on January 30, 2021, 05:14:16 PM

there actually doesnt appear to be an option for centre, only positive or negative(...?) 

Of course there is.. I guess it's an universal dc adapter, just google "center positive" and you will see how the connecter should be positioned. it's either negative or positive..  adapter is always preferable imo. USB can create noise sometimes. 

edit, image:

(https://upload.wikimedia.org/wikipedia/commons/thumb/8/84/Centre-positive.svg/120px-Centre-positive.svg.png)

so the arrow on the first connector part (which is connected to the cable) should point towards that marking on the attachable connector..
This is how it's done on all the universal DC adapters that i have at least, and i have quite a few..

Title: Re: DC power adaptor- correct polarity..?
Post by: christianlukegates on January 30, 2021, 09:40:40 PM

hi

thanks. yes its universal, so has a removable tip which can be fitted either one way or the other (negative or positive). so should i infer from centre positive that i should be setting it up in the positive alignment? the word 'centre' suggested to me that there was a third 'middle' option between positive and negative.. (im not very good with electronics in this way..!)

Title: Re: DC power adaptor- correct polarity..?
Post by: vurt on January 30, 2021, 10:07:18 PM

no, there's just these two, and yes like the image.