MP3Car.com - View Single Post - DC-DC PSU that is NOT opus/inverter question

jusatry · 12-27-2003, 07:10 PM

Quote: Originally Posted by MikeH

Jusatry,

I have measured the current consumption of my C134 with slim (laptop) HDD and slim (laptop) CD/DVD. The total input current varies from 2.7 to 3.4 amps under all conditions (cold startup, spin up, etc). My math says that a power consumption of (12x3.4=) 40.8 watts max. I would say that you could easily get by with a 60W external regulator if your configuration is similar.

I looked at the iDot regulator. If you look at the back of the unit (on their web site) you will see that it is an EDAC Power Car Adapter. The specs on this unit says it's the model 1060 with a 19V output. I looked on EDAC's web site for more detailed specs, but could not find this unit. This makes me nervous. The also don't offer a 12V version on their web site. I'm not sure how iDot is getting a 12V supply from EDAC.

Another thing to consider, as you use your carputer more, you will find that pushing a button to shut down your computer is very inconvenient at times. You'll find yourself having to wait for the computer to shut down as all you friends pile out of your car and run into the movies.....while you're sitting there waiting for the stupid thing to gracefully shut down. I've found that the ITPS is very convenient for starting and stopping the carputer.

However, ITPS is NOT a good solution for an external regulator. It has a linear regulator that requires 1.3V drop from input to output to maintain a constant 12v output. This means, any time your car battery/alternator drops below (12+1.3=) 13.3v your output 12v will drop also. My battery is a little old and sits around 12.5v when the engine is not running. In the C134, this 12v feeds directly to the motherboard.

Now, what I'm NOT sure of, and what I'd love to hear from others is.....what does the motherboard use +12v for? If it truely is NOT used on the motherboard itself, you may get away with a looser spec on the 12v. All I know is, Casetronics states on their FAQ that the 12v input needs to have a tolerance of +/-5% (ie 11.4v to 12.6v).

Just some random thoughts..... hope it helps.

Mike:
Thanks so much!

I bought the radio shack item Garry suggested and am planning on (hopefully tommorow) cutting the cig lighter end, adding an inline fuse and wiring it to the battery (actually a dist block under the dash in my car).

I can imagine the inconvinience of waiting for shutdown, and i have 2 questions, one for Garry, one for everybody. 1. Garry said in an earlier post that he uses the external regulator (the shack) and an ITPS card. how did he do this, since in the most recent post it appears you are saying this does not work? 2. can you shut the car down while the 'puter is going through her fancy shutdown rituals, if the power is routed directly from the battery?

Thanks for the help, i appreciate it.

By the way, you can call me shamir.

12-27-2003, 07:10 PM	#13
jusatry Maximum Bitrate Join Date: Nov 2003 Posts: 863	Quote: Originally Posted by MikeH Jusatry, I have measured the current consumption of my C134 with slim (laptop) HDD and slim (laptop) CD/DVD. The total input current varies from 2.7 to 3.4 amps under all conditions (cold startup, spin up, etc). My math says that a power consumption of (12x3.4=) 40.8 watts max. I would say that you could easily get by with a 60W external regulator if your configuration is similar. I looked at the iDot regulator. If you look at the back of the unit (on their web site) you will see that it is an EDAC Power Car Adapter. The specs on this unit says it's the model 1060 with a 19V output. I looked on EDAC's web site for more detailed specs, but could not find this unit. This makes me nervous. The also don't offer a 12V version on their web site. I'm not sure how iDot is getting a 12V supply from EDAC. Another thing to consider, as you use your carputer more, you will find that pushing a button to shut down your computer is very inconvenient at times. You'll find yourself having to wait for the computer to shut down as all you friends pile out of your car and run into the movies.....while you're sitting there waiting for the stupid thing to gracefully shut down. I've found that the ITPS is very convenient for starting and stopping the carputer. However, ITPS is NOT a good solution for an external regulator. It has a linear regulator that requires 1.3V drop from input to output to maintain a constant 12v output. This means, any time your car battery/alternator drops below (12+1.3=) 13.3v your output 12v will drop also. My battery is a little old and sits around 12.5v when the engine is not running. In the C134, this 12v feeds directly to the motherboard. Now, what I'm NOT sure of, and what I'd love to hear from others is.....what does the motherboard use +12v for? If it truely is NOT used on the motherboard itself, you may get away with a looser spec on the 12v. All I know is, Casetronics states on their FAQ that the 12v input needs to have a tolerance of +/-5% (ie 11.4v to 12.6v). Just some random thoughts..... hope it helps. Mike: Thanks so much! I bought the radio shack item Garry suggested and am planning on (hopefully tommorow) cutting the cig lighter end, adding an inline fuse and wiring it to the battery (actually a dist block under the dash in my car). I can imagine the inconvinience of waiting for shutdown, and i have 2 questions, one for Garry, one for everybody. 1. Garry said in an earlier post that he uses the external regulator (the shack) and an ITPS card. how did he do this, since in the most recent post it appears you are saying this does not work? 2. can you shut the car down while the 'puter is going through her fancy shutdown rituals, if the power is routed directly from the battery? Thanks for the help, i appreciate it. By the way, you can call me shamir. Last edited by jusatry; 12-27-2003 at 07:13 PM.