Electronics In car 12V and 5V..?

hiya i was thinking about my project for the car the other day and thought " the car uses 12V already... " and its DC, so all thats left is a 5V to make...

has anything been devised before to get this set up ? or is it just a case of usin some voltage regulators?


cheers peeps

 

voltage generators should be ok.. but uou need one to handle enough amps....

but you will still need negative voltages and 3.3 volts...

 

aghrr i forgot about the motherboard connections, what a plum

 

don't worry.. it's possible to make negative voltage generators... problem is making one with enough amps..

 

Couldn't you just use the guts of an old power supply, and pitch in the 12v supply from the car batterey after the transformer and rectifier, but before the smoothing caps.

The voltage ragulators and smoothing circuits would then deal with making the right supply characteristcs.

It might depend on what the transfermer steps wth input down to - but, i'm sure it could be sorted out quite easily.

Of course, if you were running a full system from a car battery, you'd flatten it quite soon.

 

ahh good thinking batman

possibly get a second battery with a split-charge relay.. just like the big power ICE boys do... would a pc really use that much juice?

 

it's not that easy i'm afraid... normally you have a voltage drop over all the regulating circuits... often up to 3 volts... A car battery CAN reach 15 volts (well.. the engine does anyway) that is just enough... so you might get some low-voltage problems... also: you still need that negatives...

but it really depends alot on how the PSU is buildt up...

 

You can get the +12v supply when the engine is running, using a low drop-out 12v regulator, but when the engine stops and it's battery only you could hit problems. Easy cheap way is a 12v-mains inverter and a standard psu.

 

ive seen some dc-dc SFF psu's before. Try googling for a car power supply.

 

the tiny Mini it-x power supply's run on 12v. also a company called "opus" makes the best dc-dc power supplys for cars. go to www.mp3car.com to lears more about car pc's

 

Yeah, the external PSUs used in Cubid cases and other such mini-ITX ones are what you want to look for. All they do is convert the mains into 12VDC which then goes to a tiny PSU board inside the case which is what you want.

Just skip the adaptor and you should be sorted. However, they're generally very low wattage (55-70) which is fine for mini-ITX but won't power an ATX system.