I went through the design and built (3) of these so far. Hope this helps other do it yourself enthusiasts. Details can be found at timothyb.net

Originally Posted by timothyb1969

I went through the design and built (3) of these so far. Hope this helps other do it yourself enthusiasts. Details can be found at timothyb.net

amazing, good info, should be stickied!

Originally Posted by timothyb1969

I went through the design and built (3) of these so far. Hope this helps other do it yourself enthusiasts. Details can be found at timothyb.net

Great design - many thanks. I like the fact that you've included the calculations too!! I wonder if there'd be enough interest to have a screen PCB design done? Let's see how many posts this thread attracts!!

Tim

Well done.
Both for the design and for the presentation on your webpage.

Doubt my wife will let me hack into the dashboard though...

Yes - but you could make it into a unit that connects between the 12 volt outlet and a floating USB socket. I was going to suggest getting my students to design the PCB but then I thought the better of it.....

Tim

Thanks everyone for the feedback. I did the work and decided to spend the time to share it with others should anyone want a cool project that is also very useful in the car.

You could apply this design to a floating 12 socket (cigarette lighter) with a cable going to a usb plug. My design objectives were to
1> Not use the cigarette lighter because it is big, bulky and stick out.
2> I wanted to keep the number of adapters, plugs, etc to a absolute minimum.
3> I wanted them to be panel mount so that all the electronics are hidden behind the dash.
4> I needed multiple plugs for her. I originally had just two and expanded to (4) as she would sometimes need to plug (3) items in. (i.e. her iphone, her bluetooth headset, and her GPS). Now if I am I am in the car with my iPad or iphone on a trip, even more reason for having (4) outlets.

Some might say excessive but we use them. And since the plugs I selected are dual usb, I only had to panel mount two connectors to get (4) usb plugs. And each one can supply 5vdc/2A/10W needed to operate and power an iPad 2.
I considered a PCB. You can buy kits from Radio Shack or I am sure from Digi-key or Newark Electronics but I was not sure how wide each trace would have to be to be able to carry the full current at 12vdc and 5vdc/2A. It would be great if someone who had this knowledge could add to this post because wiring and soldering it by hand was a challenge and you can see from the pictures that is was not pretty although funtional and plenty of current carrying capacity. Especially worth it if someone was going to make more than one the time to layout the board would be worth it maybe.

Nice work! You don't happen to be a ham radio operator do you? A lot of folks interested in electronics are. A question: Does the regulator get hot with long use, and would you recommend adding a heat sink to it?

Thanks for your comment TheHamguy1. This dc to dc co converter does not require a heat sink per it's specifications. Now I am not sure about how hot it gets. Since it does not require a heat sink I would not expect it would get that hot but I would want at least a little air around it cause it will give off some heat. I will try it in my truck next time a take a long enough drive and will get back to you.

I did make a mistake in my last post when I said the each USB adapter can supply 5v/2A. Each converter can supply 5vdc/2A/10W total for both ports combined. Since the iPad 2 requires this amount of power all by itself, when charging an iPad, you may not have enough power to charge another device. You definitely cannot plug two iPad 2's I to the same module as this would require 4A which this unit is not capable of supplying.

So if you will need to charge two iPads at the same time, you will need two dual port USB chargers.

Oh. Forgot to answer your question. I am not a ham radio operator but I am a EE and I am always making stuff for myself when I cannot buy.

Originally Posted by timothyb1969

Thanks everyone for the feedback. I did the work and decided to spend the time to share it with others should anyone want a cool project that is also very useful in the car.

You could apply this design to a floating 12 socket (cigarette lighter) with a cable going to a usb plug. My design objectives were to
1> Not use the cigarette lighter because it is big, bulky and stick out.
2> I wanted to keep the number of adapters, plugs, etc to a absolute minimum.
3> I wanted them to be panel mount so that all the electronics are hidden behind the dash.
4> I needed multiple plugs for her. I originally had just two and expanded to (4) as she would sometimes need to plug (3) items in. (i.e. her iphone, her bluetooth headset, and her GPS). Now if I am I am in the car with my iPad or iphone on a trip, even more reason for having (4) outlets.

Some might say excessive but we use them. And since the plugs I selected are dual usb, I only had to panel mount two connectors to get (4) usb plugs. And each one can supply 5vdc/2A/10W needed to operate and power an iPad 2.
I considered a PCB. You can buy kits from Radio Shack or I am sure from Digi-key or Newark Electronics but I was not sure how wide each trace would have to be to be able to carry the full current at 12vdc and 5vdc/2A. It would be great if someone who had this knowledge could add to this post because wiring and soldering it by hand was a challenge and you can see from the pictures that is was not pretty although funtional and plenty of current carrying capacity. Especially worth it if someone was going to make more than one the time to layout the board would be worth it maybe.

This Java script calculator seems to do a pretty decent job of calculating how much current a particular PCB trace can carry - with a significant number of optional inputs too.

The CircuitCalculator.com Blog » PCB Trace Width Calculator

Tim