Need to make a 12v to 5v (usb) adapter

[rcmarty]

I'm sure it's a simple project to make up. Figured i'd ask for a bit of help.

Why ? I have a garmin gps i want to mount to my quad, want to run it off the usb cable (powers the unit and keeps the display lit for easy reading).

My quad doesn't have a 12 lighter socket but i'm happy with a smal board for gps use only, i hear the a lighter socket on a quad is a pain anyways.

I'm thinking a simple reg maby a switching reg/chip of some sort. I know how to solder and i'm good with electronics but i'm not a circuit wizard by any means.

Thanks for any help.

MArtin :)

[Malc C]

The good news is that if the device gets its power from a USB socket then it doesn't need a high current draw as the 5 volts from USB is rated at 500mA tops. Therefor you should be able to use a simple 1 amp voltage regulator and a couple of capacitors to drop the 12v DC to 5V DC.

[BlitzK]

Yup, a 7805 should do the trick just fine...

[Brandano]

Or just buy an ipod car adapter knockoff.

[phil_g]

Poundland has cigarette-lighter socket to USB adapters, they're really not worth making.
Phil

[Malc C]

My quad doesn't have a 12 lighter socket but i'm happy with a smal board for gps use only, i hear the a lighter socket on a quad is a pain anyways.

Phil, that's not much use if he doesn't have a lighter socket fitted to his bike :rolleyes:

[rcmarty]

If i were going to get the adapter i'd need to tear out the insides and repackage them to the machine. I'm going to see if i can get the 7805 reg and make it up that way would be alot less that way. If not back to gutting a socket adapter.

Is there a need for a few caps ? I'd assume the charging system is the same as an automotive system varying from 12v to 14.4 volts.

Thanks for the tips and part numbers , much appreciated.

Has anyone seen or heard of a 90 degree mini usb 5 pin cable ? Mabe a swivel ? A 90 would need to have the cable exiting the narrow section of the mini usb 5 pin connection. Viewed from the top : wide part of mini usb , narrow part , then cable. The reason i ask is that i'm looking to keep the connector tight to the gps that way the vibrations and movement won't ruin the mini usb port. The best i've found so far is a laptop retractable usb cable. Being the wire is light and very flexable it won't stress out the connection to the gps. I bought 3 off ebay for $8 . One for my machine , one for a friends , and one to cut up and see if i can make a 90 connector out of.

Martin :)

[Chippie]

Is there a need for a few caps ? I'd assume the charging system is the same as an automotive system varying from 12v to 14.4 volts.

Martin :)


The caps are needed to maintain the stability of the regulator....

[rcmarty]

What type of caps would be needed ? I read somewhere a small load (1000ohm) helps also.

Martin :)

[weber_alejandro]

A parallel of 0.1uF and 0.01uF in the input and the output, very close to the pins do the job and rejets RF. If your source of 12v have ACV noise just put a couple of 2700uF/16v electrolitic in the input to help filtering.

Greetings

[phil_g]

Poundland has cigarette-lighter socket to USB adapters, they're really not worth making.
Phil

Phil, that's not much use if he doesn't have a lighter socket fitted to his bike :rolleyes:

I meant that he could use the guts of the adapter rather than build a regulator...

On the other hand I cant see a problem with fitting a fag adapter, it would be handy for keeping the battery charged too... you can get sealing ones, we use them on our trail bikes... no prob with water getting in.

Happy Christmas Everybody!

Cheers
Phil

[rcmarty]

Now that's a good idea phil. Right now the quad is new and it's getting alot of runtime (winter here , poor heli's are getting dusty) but a solar panel or battery minder is a good plan to keep get the most life out of the battery.

Maby what i should do is put in one but with a dean ultra connector, then build up a deans to lighter socket adapter. This would make temp use of lighter socket driven stuff. The deans ultra will give a solid connection for the battery charger and polarity won't be an issue. Put a dummy plug in when not in use.

Still going to harvest a lighter socket plug for the gps. I think this will be the easiest thing to do. The gps is going to be a permanent fixture so i don't mind making special provisions for it.

Martin :)

[Chippie]

Maby what i should do is put in one but with a dean ultra connector, then build up a deans to lighter socket adapter. This would make temp use of lighter socket driven stuff. The deans ultra will give a solid connection for the battery charger and polarity won't be an issue.

Martin :)

Dispense with the ciggy lighter....connect a deans connector( female...) to the battery, then a mating connector to either your solar panel for charging or for connecting the gps unit...this way keeps things tidy and light...no bulky connectors....
If weather/water proofing is a requirement, then I'm sure you can hide it away...