12v To 5v

[Guest Cepheus]

All,

 

GCSE electronics seems so long ago (16 years to be precise!) and my V=IxR isn't up to scratch so ....

 

I'm looking to hard wire the power for my Navman F20 into the car as I hate having curly cables trailing across the dashboard. Have found a suitable switchable live from behind the headlight multiswitch, but I need to reduce the 12v down to 5v. What's the easiest/cheapest way of doing this? Is it just a case of soldering the correct value resistor in line or is there more to it?

 

Your help as always is appreciated :bigemo_harabe_net-196:

[Guest neil_wiles]

Theres more to it as the resistance of the unit itself will interact with the values you choose and then the resistance of the unit will change depending on the level of charge already present in the battery.

Best way is to use the circuit inside one of the cheap 12v adaptors you can buy, just rip it open and "loose" the little circuit board in the dash inside a plastic box or similar.

 

Much better as they are current detectable and will maintain 5v regardless of the battery state in the unit.

[Guest Cepheus]

Thanks Neil ...

 

Guess it would be easy enough to take the circuitry out of the 12v plug on the end of the charging lead and use that then?

 

I shall get planning in work tomorrow :bigemo_harabe_net-196:

[Guest MATT jr]

thats what i would do aswel.

 

better than destroying your satnav like one of my mates did! haha

 

POOF, and the satnav, is gone! (said to the tune of the cilit bang advert)

 

MJR

[JohnR]

thats what i would do aswel.

 

better than destroying your satnav like one of my mates did! haha

 

POOF, and the satnav, is gone! (said to the tune of the cilit bang advert)

 

MJR

 

There are a couple of options, having just done it myself.

 

1) You can go to the local car radio shop and buy a DC/DC converter made for the job for about

[bigdaddy]

Or go to maplins and buy a cigar lighter adapter 12v to 5v for about

[JohnR]

Or go to maplins and buy a cigar lighter adapter 12v to 5v for about

[RADIOTWO]

All,

 

GCSE electronics seems so long ago (16 years to be precise!) and my V=IxR isn't up to scratch so ....

 

I'm looking to hard wire the power for my Navman F20 into the car as I hate having curly cables trailing across the dashboard. Have found a suitable switchable live from behind the headlight multiswitch, but I need to reduce the 12v down to 5v. What's the easiest/cheapest way of doing this? Is it just a case of soldering the correct value resistor in line or is there more to it?

 

Your help as always is appreciated :bigemo_harabe_net-196:

 

Or if you want to make somthing, Get a 5volt Regulator from Maplins, 12 Volts in and 5 Volts out, Don't quote me but I think it is a 7805, and at a guess about 50P

 

Radiotwo

[Smilge]

Or go to maplins and buy a cigar lighter adapter 12v to 5v for about

[Guest Cepheus]

Cheers all, that particular Maplin device doesn't give 5v output though and hasnt got the mini usb connector that the gps needs. I'll just butcher the charger lead and make use of it's gibletts :lol:

 

Thanks again

[Guest MATT jr]

..or if you can find space behind the dash, buy an extension lead, like this, cut the "male" plug off, hard wire that in, then plug your power adapter into that, - that way, your not butchering your power lead.

 

all hidden behind the dash.

 

MJR