Electronics help needed!

The_blue

The_blue

The_blue

Soldato
Joined
25 Oct 2002
Posts
4,198
Location
Derbyshire
Whats the cheapest way of converting 12V DC from a car to 19v DC for an old laptop?

I could use a 12v -220v AC inverter and the regular lappy charger but thats got to be a waste, plus i'd like something i can leave in the camper.

Is there anything simple i can build? Have solder and ******s ;)
 
you can get universal car-laptop adaptors.
Have variable voltages (between 12 -21 usually) and have various tips depending on your laptop and they plug into the 12v socket in your car.
Available from various highstreet competitors.
 
The_blue said:
I could use a 12v -220v AC inverter and the regular lappy charger but thats got to be a waste, plus i'd like something i can leave in the camper.
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That probably is the cheapest way of doing it unless you can buy a notebook charger that runs off 12v for less. It isn't a waste, just because a notebook is using 19 volts doesn't mean that the rest is being wasted, current is the important measurement.
 
I bought a power adapter for 60 quid... it converts a normal 3 pin into a car cigarette lighter cable. I used it to power a Playstation 2 in my car... it works fine and you can buy them from Flaplin.

I think this is the safest option?
 
You can build one for about 10 quid i reckon. You'll need to convert the DC power supply to AC and use a step up transformer with a bridge rectifier on the other end to convert it back to DC as the current you require is fairly high. Depends what your laptop needs in the way of amps but if you get some power transistors to power one side of the transformer they can easily pass above 6 amps with a heatsink which is more than adequate.
 
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Ladforce said:
You can build one for about 10 quid i reckon. You'll need to convert the DC power supply to AC and use a step up transformer with a bridge rectifier on the other end to convert it back to DC as the current you require is fairly high. Depends what your laptop needs in the way of amps but if you get some power transistors to power one side of the transformer they can easily pass above 6 amps with a heatsink which is more than adequate.
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Not so easy to make your own DC to AC converter though, would probably introduce too much loss, depending on the power requirements for the laptop.
 
delta555 said:
Not so easy to make your own DC to AC converter though, would probably introduce too much loss, depending on the power requirements for the laptop.
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Using an audio transformer ( as we dont need huge voltage ) and power transistors driving it the loss would not be too great and the circuit is actually very simple to create. From memory it required around 10 components or so?
 
RobH said:
That probably is the cheapest way of doing it unless you can buy a notebook charger that runs off 12v for less. It isn't a waste, just because a notebook is using 19 volts doesn't mean that the rest is being wasted, current is the important measurement.
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I didn't mean waste it that context.

A 12v to 22v inverter is about 60-80% efficient, then add on the loss from the lappys power brick = one quickly flattened battery.
 
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