Determining DC adapter

[selanac]

Hello all,

I'm trying to figure out how to choose DC adapters. I understand I have to consider all the elements like, Current, Voltage and power.

I've seen many adapter spec's drawings, but they're confusing.

I have a couple of Color Car Reverse Cameras. One 9 volts, and one 12 Volts. I've seen a person use a 9 volt battery with his instead of hooking up to the Reverse Backup lights.

I'd like to use these same cameras in other applications with either a 9 volt battery or a DC Adapter. How do you determine which one to get? Also want to use the 9 volt with the 12 volt Color Car Reverse Camera. The threshold is 9 to 12 volts. So either a battery or DC adapter should work.

Will you point me in the right direction?

Do I just check the spec's for Voltage and Current? Some Adapters have weird symbols, and even though they same specs the look different: ----Co----- or other direction. The O should be inside the C, but didn't see a drawing package here or able to attach photo.

I attempted to attach a picture. Don't know if it did or not. Can't see it.

 

[selanac]

Check out the - and +. To the right side is a symbol. Not sure how to read those. Anyone have an explanation?

 

[KJ6EAD]

That's a symbol frequently used to indicate the polarity of a coaxial DC power plug or jack. In your example the center pin is positive.

 

[selanac]

KJ6EAD,

So if I hook up a 9 volt Battery adapter do I still just hook up Black to Black and Red to Red or do I have to match the colors with the Center Pin.

I'm asking cause one of my setups started getting real hot when I connected the battery. I must have a short in it.

 

[KJ6EAD]

I don't know. I can't tell from here. My meter leads are too short.

Okay, now the serious answer. I don't know. Ordinarily red indicates positive and black negative but sometimes things get reversed. Can you check the polarity of your supply with a meter?