PC-Mobile Bluetooth Converter & Leadtek Wired GPS

SpeedCam

Has anyone managed to connect a Leadtek Wired GPS receiver to a Bluetooth converter?

Why do you want to do this.... I can hear you all ask ? ? I like the benefits of BT ie no wires or special connectors, but hate having to remeber to charge the units. Therefore if I can connect my Leadtek to the PC-Mobile BT adaptor I'd have the best of both worlds.

What I'm planning to do is use an old TomTom 'Y' cable that connects a PDA to a Leadtek GPS & powers both from the cigar lighter. I'll chop the PDA plug off the end, and connect it to the internal circuit board of the BT Converter. In theory this should do the trick.

SpeedCam · Posted: Tue Jan 04, 2005 11:41 pm Post subject:

Ahhh one question I did forget to ask is, does anyone know how to reduce 5v DC to 3v DC. I'm hoping its as simple as purchasing a particular resistor, if some can provide any details I'd be most grateful

Cheers

DavidW · Posted: Wed Jan 05, 2005 5:00 am Post subject:

The voltage regulation required for digital circuitry needs to be far more sophisticated than a couple of resistors wired as a potential divider, I'm afraid. There's various regulators available - though do make sure you've got full crowbar protection in whatever circuit you decide on.

Another problem with your setup is how are you going to get 5V power for the Leadtek GPS - or was that what the question was about?

I don't understand how the Bluetooth adapter solution is any more flexible than a Bluetooth GPS when it comes to power. With my Clip On, I can run from battery or from external power. If I apply external power and the battery isn't fully charged, the battery will charge at the same time as the GPS is in use. Finally, I have the option of switching an exhausted battery for a fresh one.

What can your proposed Bluetooth adapter solution do that my Clip On can't so far as power goes?

David

SpeedCam · Posted: Wed Jan 05, 2005 2:55 pm Post subject:

To answer the first question, I'm planning to use a standard TomTom 'Y' cable that plugs into the cigar lighter. Then one end connects & powers the LeadteK the other powers the PDA, I'm planning to chop the PDA connector off and re wire into the BT converter. This is why I asked the question regarding 5v to 3V. The 'Y' cable provides the 5v for the Leadtek, but the BT converter normally runs from two AA batteries ie 3v.

The benefits..., I'm planning to hide the BT converter in the car and have it wired into the ignition. When the car is started the unit will automatically start.

The benefits over a standard BT GPS unit such as EMTAC, currently I have to either remeber to charge the EMTAC before travelling, or keep connecting disconnecting the in-car charger. Also from a secirity point of view I always remove the BT GPS unit. I've also considered permantely installing the EMTAC into my vehicle, the only problem is that when the car is not used, the battery then runs flat and the unit defaults to SIRF mode.

Hope this helps.

DavidW · Posted: Wed Jan 05, 2005 10:14 pm Post subject:

With my Clip On, I simply have the magnetic mount supplied in the box mounted on the top of my ProClip, and there's a hard wired power cable there as well, tied down well with cable ties so that it doesn't flap around.

All I have to do when getting in the car is drop the Clip On onto the magnet, plug in the power cable and switch on. When I get out of the car, I switch off, unplug, and take the GPS and iPAQ with me. It works well enough for me.

David

Falkien · Occasional Visitor Joined: Jul 14, 2004 Posts: 48

SpeedCam

How's your soldering?
You'll need a Linear regulator to give 3v from the 5v supply, you could house it inside the battery compartment of the BT adaptor
It's a simple circuit

Have you tried the setup using batteries and got it working?

Can you give more details on the BT adaptor, I've had a quick search and can't find a PC-Mobile BT adaptor using Google

Dave

Falkien · Occasional Visitor Joined: Jul 14, 2004 Posts: 48

Okay, so I should have searched the PockeGPSWorld forums Embarassed

I guess http://pc-mobile.net/bta.htm is what you mean?

I'm guessing also that the leadteck outputs at 4800 as default

Okay

5v to 3v or 3v3 is probably easier and shouldn't be a problem since the voltage of brand new Alkaline cells can be as much as 1.7v initally

If you are in the UK look at www.farnell.com order number 120730
Its a linear voltage regulator LM1117T-3.3

the datasheet http://www.farnell.com/datasheets/45150.pdf shows that it will require a couple of 10uF caps (pinout is on page 3)

Order code 4164192 is a 10uF Tantilum Cap that is suitable (The stripe on the bory of the cap indicates the positive terminal)

You could solder the components to a piece of stripboard or just solder the terminals together making sure you insulate to prevent shorting

HTH

Dave

SpeedCam · Posted: Thu Jan 06, 2005 8:42 pm Post subject:

Falkien, thanks for your detailed reply this is exactly what I need, as you suggested I'm going to make sure my idea works with batteries first and then solder the cable internally.

I'm reasonablly OK with soldering cables and basic electric's, but resistors, capacitors etc etc are out of my league. As long as someone can tell me what to buy, and what needs connecting to what I'm OK

Yet again thanks for your help

SpeedCam · Posted: Thu Jan 06, 2005 10:24 pm Post subject:

Falkien,
Hopefully my last two questions, I think I understand how this is working...

1. The two capacitors, both connect to the GND pin and each of the + pins connect to the In & Out. So in summary I'll have GND wire connected to the GND PIN of the regulator & the two - pins of the Capacitors. My +5v will connect to the IN along with + from one capacitor. The OUT will connect to the other + from the other capacitor and will give me the +3.3V that I require?

2. Is there an alternative source for these parts, I'm struggling to get the order upto £2, and their minimum order is £20?

Cheers

Falkien · Occasional Visitor Joined: Jul 14, 2004 Posts: 48

THat's it - The regulator IC does all of the clever stuff, the Capacitors help to prevent the regulator from oscillating

The £20 limit at Farnell is a problem

I looked initally at Maplin, but they don't seem to stock 3v3 regulators
Others to try are

http://rswww.com
they also have trade counters, so you can pick up in person to save postage

The Regulator is RS part no. 349-4717
Suitable Caps RS Part No. 461-2871 (minimum order qty is 5)

http://www.rapidelectronics.co.uk (orders under £25 have a £3.25 delivery charge)

Dave

SpeedCam · Posted: Tue Jan 11, 2005 6:51 pm Post subject:

I'm not sure if anyone else is interested in this, and would like me to take some pictures whilst I'm building it?

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