I'm getting bored...

marsjell · 04-24-2003, 06:21 AM

I've really had it with all the stupid power supplies... I used to run my TFT (12,1 touchscreen) off my computer PSU (presslab idea) but it ran very hot and later when I added a 60gb 7200 rpm HD the hd would only spin up if my tft was off.
So I build a seperate ps for my tft I've used this ps last year for about a week , all great. I haven't had much time untill today so I wanted to place my TFT in the dash (as opposed to the rear seat), ok everything connected/inserted/screwed down. I start my comp, tft comes on and where ready to roll.... 15 min later I heard something that I haven't heard before a squeling noise from behind my tft. Quickly turned off my comp and the squeling stopped. the cooling parts of the ps where hot as hell so I should fix this. anybody know of a stepup/down regulator circuit for 2,5A 12V ? mine was rated at 1,5A 18V so I figured with a little redesigning I could get 12V and the max power would go up enough, well evidentiely it hasen't...

Any good Ideas before I throw my setup out the door and buy a "normal" kenwood or Pioneer radio/mp3 player?

dchaug · 04-24-2003, 10:03 AM

LM2587T-12

Should be more than adequate.

peter3 · 04-24-2003, 08:16 PM

marsjell:
if you need a lm2587t-12 let me know.
i have some spare.
Peter3
Deventer

Raas · 04-25-2003, 09:08 AM

maybe the max1771 could do the trick
http://pdfserv.maxim-ic.com/arpdf/MAX1771.pdf
2v-16,5v input and 12v@2a output (If i´m not mistaken... )

PS.... If you would throw it all away, I´d be happy to be your garbage-can

hahaha j/k

Greetz

marsjell · 04-26-2003, 06:33 AM

Raas, I read through the PDF but I'm figuring the max power is about 500 mA @ 12 V.... could you specify where you read about the 2A ?

Is there anyway to build a PS without using coilcraft coils? They won't send me a sample, they won't even sell to me I just don't know where to get them...
The lm2587t-12 seems to be the best option, but it requires those damn coils... the pdf I found gives me some alternatives to coilcraft but I can't seem to find those either...

Raas · 04-28-2003, 03:48 AM

Quote:

Originally posted by marsjell
Raas, I read through the PDF but I'm figuring the max power is about 500 mA @ 12 V.... could you specify where you read about the 2A ?

Hi, looking at the schematics they suply in the datasheet it says 0,5a, but why are they talking about 24w output then?
There are more members on this board who have used this component, If I´m not mistaken Dima has used them succesfully!
(maybe has something todo with a 5v input.....)
Greetz,

marsjell · 04-28-2003, 04:06 AM

Raas thanks for your info.. it seems bit silly though, converting 10-14V input into 5V using a 878 and than using a 1771 to get 12V ??
Think I'll take a look at maxim's website to see if they have any other options...

just visited maxim... is there some thing wrong with this option :

http://pdfserv.maxim-ic.com/arpdf/MXL1074-MXL1076.pdf

??

Raas · 04-29-2003, 04:34 AM

Hi. seems interesting, but can it do step down and step up in the same setup.. From what I read, it´s a step down convertor, which also can be used as a step up... but in the same circuit ???

Yeah.. seems silly, to bring the voltage down first to 5v and then have it up to 12v.. but If I´m not mistaken that´s the only way to get 24w out off the 1771... (I´ll do some research, and have a look at dima´s postings to see how he has done this.. )

This weekend I´m going to put in the second carputer.. again running off an inverter.. when I have it in.. i´m going to build me a dc-dc... I have enough components laying around... I decided to put the carputer in on the inverter, because, when It´s not in the car, it´s on my desk, and then I constantly keep changing things, leaving me no free time to build meself a dc-dc.... (I´m not actually sure why the first system died.... mobo and video failed on me the at the same time.

Greetz,

marsjell · 08-05-2003, 10:33 AM

The beautifull wheater has re-inspired me to work on my mp3 setup and I was thinking, as I said the PS for my TFT has worked ok when I first tested it and some time later it squeeled and got hot. When everything was ok my battery was fully charged, and I tested it on the road. When everything wend bad, the car wasn't running and my battery wasn't optimal (had been driving around when both amp's pumping).

Could it be that a stepup stepdown supply gets warmer when it needs to step up the voltage more? seemed suddenly logical to me? Do they also get very hot when the voltage needs to be stepped down?

please help me!

Marsjell

marsjell · 08-07-2003, 02:15 AM

anybody... please?
I need your input. I don't want to test my theory by just driving around since I won't be able to hear the high pitched tone (a 2cv has an aircooled 2 cylinder boxer enginge which makes a lot of noise).. So please, any body with any knowledge on step-up/step down converters....

marsjell · 08-19-2003, 02:09 AM

come on peeps... please help me?