Charger for Laptop

[grayling]

I have tried a cigarette type 12v to 19v charger for our laptop when on-board but it interferes with our Icom VHF radio. Like similar units on the web the specification quotes EC compliance but as this one obviously doesn't I am reluctant to try another. Is any reader able to share a proven solution to charging laptops?

 

[Stork_III]

I use a Kensington dc/dc charger in a Suter 12v socket. No problems. You get what you pay for, usually.

 

[Sarum 28]

I use a Kensington dc/dc charger in a Suter 12v socket. No problems. You get what you pay for, usually.

Are the 12 Volt socket and the VHF radio on the same fuse/cable?
If yes, try to isolate the common cable as a source for the intereference you have in the boat installation.
Ferrits are you friend.
And a box made of a tin like material to run the dc/dc converter inside.
Greetings, Willy

 

[TQA]

I am writing this using a Toshiba lappie powered off 12 v with a PMR charger and as far as I know there is VHF interference.

 

[William_H]

As said the problem is more likely in the boat wiring than the charger. Try a temporary direct connection to the battery terminals. If this fixes the problem then try a direct connection to the fuse box bus. The problem is likely to be those wires that are common to both VHF and the charger. That means the negative wire as well.
As Willy says you can also try to stop the interference escaping from the charger. This is most likely via the wiring. But could also be by direct radiation from the charger hence the reference to a tin box but spacing may also help.
Ferrite is a hard material made of iron fillings or similar. When a wire passes through it or better wraps around to pass through it multiple times it forms an inductance. Inductance tends to act like a resistor to limit the passage of high frequency current variations. Used in conjunction with an inductance is usually a capacitor from pos to negative of the supply to the charger. Use a small ceramic capacitor of about .1 microfarrad but also use a larger electrolytic capacitor of 100 microfarrads in parallel. The smaller capacitor passes high frequency better than the bigger one which can exhibit some inductance in itself but handles the lower frequency variations. The electrolytic capcitor will have a pos and neg wire. These are usually paced on the side of the indctance closer to the charger but can be duplicated on the power supply side of the inductor.
All thse copmponents can be bought cheaply from an electronics store. Or can be salvaged out of an old computer power supply. Easiest for the ferrite is to feed it over the existing feed wire or you may be able to wrap the existing wire through the ferrite a few times or add additional wire but make sure it is heavy enough to take the current.
Here are some ferri6tes from an Oz supplier. The rings are best so you wrap the wire through and around as many turns as possible.
http://www.altronics.com.au/index.asp?search=Ferrite&area=srch&Submit=SEARCH
This kind of treatment is appropriate for LEDs and other devices that give interference.
good luck olewill

 

[charles_reed]

Having used a variety of 12v to laptop chargers and never suffered vhf interference, I have to believe your problem lies in the boat's wiring.

You could always turn off the laptop charger when using your vhf, if rewiring the boat electrics don't appeal.

 

[nigelmercier]

I've got two of these, http://amzn.to/1oCNOP7 "an automatic switching device that has both 12V and AC inputs, and outputs a selection of voltages from 12V to 24V..."

See this thread: http://www.ybw.com/forums/showthrea...wering-Notebooks-TVs-and-other-gt-12V-devices