Electronics Help
Turbo Mini Forums

Afternoons chaps,

I am wanting to buy if possible or make a power supply that will give out 8v and 9W from plugging in to a 12v car cigar lighter socket.

Does anyone know where I can buy such a thing, or is anyone good enough at electronics to tell me how to make one? It is to power my camcorder whilst doing in-car video.

http://www.maplin.co.uk/Module.aspx?Module...FAQS=Y&doy=29m8

They used to make a bigger one,two in parralel would work


or

http://cgi.ebay.co.uk/In-Car-Caravan-DC-DC...1QQcmdZViewItem

Think you will struggle with 8v most are 7 or 9

Edited by Dangerous on 29th Aug, 2006.

Metro turbo weekend driver,Mini turbo in the making again!

Tom, you should be able to get a kit to make your own step down transformer to do this.

Unless i'm getting confused (which happens a lot) You can't regulate the wattage that it will give out. This is determined by what you plug in to it. When you see an ampage reading on the back of a power adaptor (phone or camera etc) it's telling you the amount it's able to supply at that voltage i believe, not the amount that it actually is suppling.

Hope that makes sense.

Ric, yes I know you can't regulate amps/wattage, I just need something that is rated to supply that power/current!

A step down transformer is just the thing, but as yet I can't find anything suiatble.

I'm intrigued what you want to video in your car

Some new sort of porn?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Axel, not porn, this kind of thing-


http://media.putfile.com/tour-of-cadwell-park

You cant use a step down transformer on DC ( a battery).

But a voltage regulator should be just the thing - if no one else can help before i get home I'll look up the VRs I use :)

Alex

AlexF

Just use ohms law to find out what size resistor you need.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

You just need to Zener the voltage. Either use a voltage regulator like Alex said, or build it up with discretes on a piece of variboard.

A couple of quid should see it done. MAke sure you heatsink the regulator

Tom,

This should put you in the picture-



You can also use a voltage regulator, which is essentially a zener diode with a few passives in a single package (cheaper, easier) some tips here-

http://ourworld.compuserve.com/homepages/B...wden/page12.htm

I'd build any circuit up on some variboard.

Andy

Hi Tom,

Im an electronic engineer by trade i'll figure you summin out in the next few days and PM it over to you. I built loads for the old PS1 so folks could run them in there cars.

I can build you summin and send it if your willing to pay postage?

Karl

(P.s Sorry, i jus read this back and it sounds a bit bitchy. Wasn't meant to be. lol)

Edited by 1380turbo on 30th Aug, 2006.

Here's another link showing a circuit with a pcb and parts list.

http://www.uoguelph.ca/~antoon/circ/vps.htm

It's fully variable and designed for use with a transformer. To power it off direct DC, just loop out the bridge rectifier.

If you just want a fixed eight volts, you need to replcae 'P1' with a fixed resistor.

Andy

Edited by Andymini on 30th Aug, 2006.

Simple way is using an LM338K device. Similar to the LM317 device Andimini shows, the 338 is just higher power. Should be easily available from maplin. Its a standalone voltage regulator which just needs 2 resistors to select the desired voltage.

8V will need. . . .

240 ohm resistor from the output pin to the adjust pin (R1).

1.3K ohm resistor from adjust pin to ground (R2)

Calculation is. . . 1.25*(1+(R2/R1))

This gives 8.02V at upto 5-amps which equates to 40W. Mount the device on a small aluminium heatsink and it will run all day.

Hope this helps.

Karl

Edited by 1380turbo on 30th Aug, 2006.

Woo all these options!

Karl if you have the kit to be able to build me one I'll happily reinburse your time and expense, saves me making a bollocks of it by ordering the wrong stuff etc.

No worries buddy. PM me where you want it sent to and i'll do that for ya. Shouldn't take too long.

Karl

Well, to update this, Karl (1380 turbo) has built and sent me a power supply, it has arrived today!



It looks fabulous, a big THANK YOU to Karl for this!

Cheque is in the post Karl

ooh! in a nice box too! now theres service!!

oh hell

after reading bits of this thread i think ive just made the worst mistake of my life in going back to college

Nic, trust me mate, you have just made the BEST decision of your life, it may not seem like it for the next few years, but for the 20 or 30 after that I reckon you will be very glad you did.......

what you gonna be studying Nic?

I may have a couple of engineering books if theyre any use to you.

i hope so tom

its electrical engineering (not electronic which i just re-read), im not sure whats what yet, its all a bit new and i have very little info!

ah, what level? hnc/hnd?

is that electical as in like, mains and stuff?

i'll dig out the isbn no's so you can see if they'll be of use.

hnd,

yes i believe it is "mains and stuff" thats a good way of putting it!!haha

cheers though, pm me the details of them and ill take them off your hands when i know whats going on