DC-DC PSU that is NOT opus/inverter question - Page 2

MikeH · 12-28-2003, 10:37 AM

Gary,

Just for clarification, you are NOT using the brick (AC/DC 12v converter) that came with the C134 case...right? You have connected the INTERNAL psu in the C134 directly to your battery...right? And you haven't experienced any problems with supplying your mobo with 14V from the alternator when the engine is running?....wow, you are brave!

I think you mentioned in another post that there is nothing inside the C134 that uses the incoming 12v (other than the internal psu). Have your verified this? If this is true, then why would Casetronics stress on their website FAQ that

Quote:

We have a few models that use a DC to DC converter inside the chassis, however, we do not recommend customers to power their system directly from a car battery without regulating it first. The input for the converter is 12VDC +/-5% tolerance.

I guess now I'M the one that's confused....

jusatry · 12-28-2003, 02:00 PM

Quote: Originally Posted by MikeH

Shamir,

I don't see where Garry said this, but I (Mike) did...

I connect the input of the RS regulator to my battery thru a 20A fuse. I connect the output to the ITPS. The ITPS has two functions: 1)another 12v regulator (which I have disabled in my setup since the I have the RS in front of it. This is what I said is NOT a good 12v regulator solution), and 2) turn-on/turn-off controller. When you first turn on your car the ITPS will delay 3 seconds and then pass the regulated 12v thru to your carputer. When you turn off your key, it waits 5 seconds and then send a turn-off pulse to the carpc thru the PWRON line (it's still passing regulated 12v at this point). This SHOULD begin the graceful shutdown of the carpc. In case the carpc is "stuck" and won't shut down on it's own, the ITPC disconnects the 12v line after 45seconds, to prevent battery drain. This is a "non graceful" shutdown. If the carpc is already shut down, no problem. If it is stuck, when you turn it on the next time, it will go thru the "scandisk" routine. Undesirable, but better than a dead battery.

You can read all the details of how this works on THIS document. There a bunch of good info on power supplies in it.

I hope this helps..

Mike,

Sorry for the confusion.....thanks for the clarification

so you know how the RS thing has a tip that replicates the C134 tip? how do you keep using that if there is a shutdown controller between the voltage regulator and the computer? Also, is bypassing the regulator on the ITPS difficult, or is it just a jumper pin setting? Lastly.......how often do you go through scan disk on startup? That is, other than convinience, do you think ITPS is necessary? Thanks for the help.

Shamir

MikeH · 12-28-2003, 05:28 PM

Shamir,

Quote:

so you know how the RS thing has a tip that replicates the C134 tip? how do you keep using that if there is a shutdown controller between the voltage regulator and the computer

I cut it off and connected new wiring from the output of the RS regulator to the input of the ITPS.

Quote:

is bypassing the regulator on the ITPS difficult, or is it just a jumper pin setting

..well, sort of. The ITPS has a "solder bump" (actually 2 bare pads on the PC board) that is supposed to let you drop a glob of solder on it to bypass the regulator. For some reason it was difficult to get the solder to stick to it. So I just glopped a drop of solder between the pins of the regulator IC...same effect. So now, the 12v regulation comes from the RS regulator.

Quote:

how often do you go through scan disk on startup

It's only happended twice. The problem with the ITPS design is, if you turn on your car for a short period (I needed to move my car inside my garage from the driveway the other night...about a 20sec task) and then turn it off WHILE WINDOWS IS STILL BOOTING OR STARTING SOME APPLICATIONS, the ITPS will send the "shut-down" command 5 sec after you turn the ignition off, but windows doesn't "see" this command since it's still booting. As it continues to boot, the ITPS will shut off 12v power after 45sec. This is right in the midst of some disk access.....not good.

Anyway, some people have added and external "keep off" switch to prevent this type of situation, but I haven't....yet.

Quote:

That is, other than convinience, do you think ITPS is necessary

It is a convenience, but a BIG convenience if you use the carpc every day, every time you drive..... worth $40 to me.