Determining voltage needed...

Tibia · Post by **Tibia** » Wed Apr 23, 2008 10:41 am

I found a TV-to-Computer tuner at some thrift store. It requires a power adapter, but I don't know what voltage. I can see that the pin in the power jack is positive. Aside from a few ceramic resistors and a capacitator, the first thing the jack goes to is a converter labelled "78D05". Is this more or less a regular 7805 converter? I have some spare power blocks laying around, in about the 6-7V range. Properly wired, would one of them do the job?

Also, can the converters be connected in series to knock the voltage down further? For another project, I have a 24V power block that I need to kick down to 18V. Is that doable?

Post by **bicostp** » Wed Apr 23, 2008 10:45 am

What model is it? Can you put a few pictures up?

If there's a marking on it that shows how much power it draws (Milliamps), you could gte away with a variable power supply from Radio Shack. Put the appropriate size plug in with the right polarity, and starting at he lowest setting, keep bumping the voltage up until the device works.

Tibia · Post by **Tibia** » Wed Apr 23, 2008 11:03 am

I guess the model would be KW-TVUSB7011R/M-US. That's the number on the sticker I took off the side when I opened it up. It's the only sticker on the thing.

This is the front of it. Come to think of it, is this even what I think it is? I thought it was something that would let me use my computer as a TV.

This is the rear. The bar code is the sticker I took off the side. That's the power jack to the far right.

The insides. I don't have a camera ATM, so it's a 200% scan of the inside. I drew a red box around the converter, since I can't read the markings in the scan.

Any advice on this is greatly appreciated.

sammy · Post by **sammy** » Fri Apr 25, 2008 10:55 am

That's a 7805 so 7,5V sould do. But look around for other regulators as well, something might need a higher voltage.