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Legend C & Dc Power


fieldkat
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http://www.pc-mobile.net/ck203.htm

 

So, does anyone think that I would be able to connect my Legend C to one end of a USB cable and the other end to PC-Mobile's USB car adapter and NOT blow-up the GPSr? (See above link.)

 

Here's my thought about it, but I have only a slight understanding of this kind of stuff:

 

The Legend C receives power from my PC when connected. The USB port outputs 5V of power. The USB car adapter outputs 5-5.2V. So, since something in the GPSr steps the power down to 3V it should do the same with the adapter output, right?

 

I wouldn't be worried except that the adapter's specs mentions 850mA. Since I am not exaclty sure what that means, I am a little nervous about trying it out.

 

I would appreciate your opinions.

 

Thanks! - Trailkat :rolleyes:

 

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I have no experience with this particular USB adapter but here is some physics behind this.

 

A standard USB port will deliver between 4.75 Volts and 5.25 Volts (Voltage is the equivalent of water pressure in your garden hose). Your GPSr has a USB connector and it will accept such voltage. It will not blow up. Since the GPSr electronics works with only 3 Volts, it will internally bring the voltage to 3V when the power comes from the USB connector.

 

As for the 850mA that you read on the adapter, it represents the maximum current (water flow) that the adapter can deliver while keeping a voltage (water pressure) of 5 Volts. 850 mA is more than plenty to power your GPSr.

 

I am however a bit worried about the comment on the PC-MOBILE page:

We would advise disconnecting the car adapter after the ignition is turned off as a habit.
.

It seems to imply that the adapter does not have a surge protection circuit and that when your turn your car ignition on, the adapter could send a voltage spike (much higher that 5V) to the GPSr and blow it up... I the case this would happen, I don't know what Garmin would say about your warranty...

 

For this reason, I would advise you to use a Garmin adapter, even if it can be a bit more expensive.

Edited by goodweather
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Thanks, everyone.

 

I planned on going ahead and getting tha Auto-Nav kit from Best Buy. What sucks is that I can't find it at any of my local Best Buys here in Tampa, FL. The GPS and GPS accessories section at the local stores have always been on the weak-side.

 

- Trailkat :blink:

 

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I am however a bit worried about the comment on the PC-MOBILE page:

We would advise disconnecting the car adapter after the ignition is turned off as a habit.
.

It seems to imply that the adapter does not have a surge protection circuit and that when your turn your car ignition on, the adapter could send a voltage spike (much higher that 5V) to the GPSr and blow it up...

Hmmm that's interesting. I often have my Vista, cell phones, (my wife and my own) and my Ipaq PPC connected to power cables to the car's lighter outlet. I use a 1:3 convertor. I've actaully done it in two cars. My car the lighter stays powered after the ignition is shut off. My wife's the power to the lighter is shut off with the ignition ( a pain when you want to charge things when you're not in the car running the engine).

 

I haven't noticed any problem with damage although the cell phones do not hold a charge as long as charging overnight as the trickle charger at home.

 

I'm not quite sure if I'm asking a question or making a point but I threw it out there for what it's worth.

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