FYI, BG Micro now shows the Trimbles as sold out. I'll see if I get the ones ordered last eve. FWIW, they show "8 channel Motorola GPS boards coming this week" Encores?

Encore GT. $15 per. ACS1397

The Motorola need a seperate Active GPS antenna do they not?
[antenna is not sold by BG Micro and ebay is your option I think].

Vendors still sell the Motorola antenna and other vendors' active GPS antennas may also be suitable.

So what all should I be buying? I'm looking through the digi-key web site and trying to decipher the circuit diagram in the PDF. Unfortunatly, I really earned my C in electrical-engineering-for-cs-majors and I'm not really up to speed on this stuff yet.

So far, my digi-key shopping cart consists of the following
(ugly snarf&barf from table warning)
1 1 LM7805CT-ND IC REG 1A 0-125DEG C TO-220 IC2 0 0.48000 $0.48
2 1 399-1447-ND CAPACITOR TANT 2.2UF 50V 10% RAD C2 0 0.93000 $0.93
3 1 P2067-ND .1UFD @ 50VDC TANTALUM CAP C1 0 0.43000 $0.43
4 1 MAX233CPP-ND IC 2DVR/2RCVR RS232 5V 20-DIP IC1 0 7.45000 $7.45
5 1 PT5101N-ND REG 5V/1A 3P-SIP INT SWIT VERT IC2 - SECCOND CHOICE 0 14.62000 $14.62

Questions:
1) In the BG Micro PDF, what is B1? A generic pull down resistor? Or some other component I'm not recognizing?

2) Is a PT5101 worth the extra $14 to have a switching power supply instead of linear? It's recomened in the PDF for the motorola, but really adds to the expense of all this.

3) Can I actually get these at radio shack? They're not showing up when i search their catalog online... But I'd love to avoid shipping&handling.

Has anyone gotten a shipping confirmation or anything? I'm assuming mine will arrive sometime here...

Thanks,
Matthew

I think B1 is the 3volt lithium backup cell for keeping your GPS receivers "memory" backed up when the main power is switched off.

The purpose of this battery backup is to make the "Time to First Fix" (TTFF) shorter as the GPS will have some of the data it needs remembered from last time it was used.
Time To First Fix is the time taken from when you power (the GPS) up, until it reports its location (lat/long etc).
It could take a minute or more without the battery backup to report its first fix.
You could run your unit without the battery backup - but TTFF will definately take longer that way.


I got shipping notice/email from BG Micro today that my order had shipped, as Its going Airmail, I won't expect it much before early next week.

You probably don't need to expensive Switching Power Supply - the 7805 type regulator will work, provided that the excess voltage above 5 volts can be easily removed as heat from your design.
If you need a cooler operating design - then the switching Power Supply may be cooler/generate less heat.

It may also tolerate a wider voltage range - I'm not sure on the difference from the 7805 type design..

Looking at the voltage regulator....

From the data sheet, the unit draws 0.9W at 5V. Call it 200mA.

If you're running a 7805 regulating (call it) 12V down to 5V you will need to disipate (12V - 5V) * 0.2A = 1.4W which is not a small amount but with a halfway decent heatsink shouldn't be a problem.

Obviously you also have to allow for how much the active antenna draws too since it runs off the same 5V supply.

I am also looking forward to the next run...

I recently went out and installed a Holux SuperMouse NMEA GPS receiver and attached it to my Rio.

GPSapp works very well.... however, I am having a problem with empgps.

It displays the number of satellites and a 3D fix, but it does not display Lat, Long, Time, Date, Speed, or Heading.

All of the values remain at 0 even when my car is moving.

Do you think that the NMEA sentances coming out of my receiver are not being parsed correctly by empgps?

I can upload a few as an example if it would help the troubleshooting process.

TIA,

lothar

Hey Lothar.. Few questions... Where'd you order the Holux Supermouse from? How easy was the installation? Finally, how much was it?

Picked it up at gpscity.com for $170.00

The installation was relatively straight-forward. I had to create a custom serial connector to plug into the sled.

Right now the 12V to 5V adaptor is plugged into an external outlet. My plan is to find/make some sort of 12v to 5v adaptor? and wire it directly to the 12v amp lead off of the sled.

-lothar

Damn, couldn't find the Holux Supermouse on gpscity... Is it discontinued?

It's not outwardly obvious that it's made by Holux... but it is.

Here's the URL:

http://www.gpscity.com/products/gm/gm210pc-cig.html

cheers,

-lothar

Ah, sweet. I do believe I'll be ordering one of those.

Edit: Just thought of something... Does this thing draw power when the ignition is off? Like, I'm pretty sure my cig. lighter stays active when my ignition is off.. I guess I'd have to unplug it? Guess that's another reason to try to get some 12V-5V adapter to the Empeg DB9 going...