12v to 4.5v supply

[CovKid]

Anyone come across a vehicle transformer that will deliver stable 4.5v and isn't one of those cigarette plug in things? I'm wiring in a load of LED fitments that are all 4.5v and don't want to lose the extra voltage using a resistor. Need a dedicated supply of at least a couple of amps or a circuit diagram if anyone has one.

[Willoughby]

Hi

Here is what I got, gets a tiny bit warm so worth adding a heat sync.

Input +7 > 35 V output 5V 2A Output 0.91p from maplin

L78S05CV

http://www.maplin.co.uk/Module.aspx?ModuleNo=7939" onclick="window.open(this.href);return false;

Kev

[CovKid]

Well done Kev, never thought of using something that simple. Yeah, that would do it - ta

Also a good solution for the lengthy 12v TV thread I expect as theres one for 12v output too. Way to go - solved.

Ralph

[Red Westie]

Simple but will need appropriate mounting box, some care to electrically insulate with heatsink and paste...you can buy a small alluminium component case that could act as the heatsink.
Martin

[CovKid]

And presumably, by fitting both a 4.5v(5v) and 12v regulator in the box, I'd then have a regulated 12v too which would be handy. The idea is to run a second loom using small 3-core wire that I can tap into for small but sensitive modern equipment. Mind you, anything that gets warm like this will I assume be using current unless I also fit a switch or have it run only when ignition is on so will take some thinking about...

[tonytech]

The 12V regulator will need a couple of volts headroom, so may not deliver a good regu;ated supply with only 12.5V to 13V supply

T

[Willoughby]

Aye, +3 volts in the norm on the cheepy ones.

I have seen hi spec 12V 5A ones with a +1.5 will dig it out. Sure it was around the £20 mark tho.

K

[ghost123uk]

Simple but will need appropriate mounting box, some care to electrically insulate with heatsink and paste...you can buy a small alluminium component case that could act as the heatsink.
Martin

On a 2 amp 7805 (5 volt regulator) the metal mounting tag is the "earth" so no insulation is required. Plus it makes it easy to then bolt it to any suitable metal part of the van, which will act like a big heatsink Also you do not have to connect anything the the centre pin (which is also "earth")

[Red Westie]

ghost123uk....by insulating I was talking about the terminal legs...and wiring soldered to them. The regulator itself also needs a small application of heatsink paste to the rear to efficiently transfer the heat to the heatsink/alluminium casing.....like on a computer processor.
Martin

[Plasticman]

Dont ..think its any use to run a tv
m

[ghost123uk]

@ Red Westie = Ah - I see what you were referring to now

Dont ..think its any use to run a tv
m

What isn't -

[syncrodoug]

Have a look here....http://www.itx-warehouse.co.uk/productlist.aspx?Cid=36" onclick="window.open(this.href);return false;

[A KIRK]

Would something like this help?

http://www.seonline.co.uk/product.php?i ... a4974706de

[tonytech]

Would something like this help?

http://www.seonline.co.uk/product.php?i ... a4974706de

This adaptor is designed to plug in to 230V ac and give a 12V dc output.
The devices in syncodugs post are designed to work from the vans 12V battery.

T