Ideas on a very effective 5v dc converter.

[neba13]

I have a some solar panels with a 8v out put and 10 watts. I would like to build a USB converter. I have seen many plans using a 7805 regulator. and I really like how easy it is to build, but I need this to be the most energy efficient as possible. I don't know it it would be possible but I would like to have two USB each giving out 5v 1amp. thank you
Branden

 

[bountyhunter]

I have a some solar panels with a 8v out put and 10 watts. I would like to build a USB converter. I have seen many plans using a 7805 regulator. and I really like how easy it is to build, but I need this to be the most energy efficient as possible. I don't know it it would be possible but I would like to have two USB each giving out 5v 1amp. thank you
Branden

That would only take 100% efficiency.

 

[ronv]

Look for something like this:

**broken link removed**

 

[neba13]

thank you for the replys. I under stand I'm not going to get 100% efficiency, but I want to get as close as I can get. With the 7805 regulator, there is some capacitor that are need. how can I find out what kind I need.

when I go to the the website you posted, it says that that page has been deleted.

thanks Branden

 

[ronv]

Hmm. works ok for me..

A 7805 is not the best for solar because the input has to be about 7 volts to get 5 volts out so it is not very efficient and won't work when you don't have a lot of light on your solar panel. The buck boost converter has 80 85% effeciency and will put out 5 volts even when the input is less than 5 volts.
If you can't get the link to work just go to ebay and look for buck boost converter.

 

[neba13]

thank you ronv. that is exactly what I'm looking for and a really good price. I really wanted to make one though. I was not and to find any blue prints on it. do you any any ideas?

 

[ronv]

They can be tricky to build. If tou want to build one the 7805 would be easiest. Just follow the examples in the datasheet.

 

[neba13]

OK. what data sheet should I follow? the biggest issue I'm finding is I don't know the right capacitor to use. I always see other people using all different types. any thoughts?

 

[ronv]

I would follow Figure 10 in this data sheet. Ceramic capacitors located close to the regulator pins will work fine. You might want a little heatsink.

https://www.electro-tech-online.com/custompdfs/2012/07/LM7805.pdf

 

[neba13]

thank you so much. that is what I exactly what I need thank you for all your help.

 

[ronv]

Thanks. Good luck & have fun!