Electrical Experts of the KB

[Scuba_Steve]

I have a source voltage of 12-14.4v give or take [read car battery], what's the easiest way to ensure this supply is only 12v???
The device I want to use is 12v DC but I'm not 100% it can handle the surge to 14.4v of the charging batt as it was never designed for automobile applications. It was designed for a steady 12v supply

Is the below what I'm looking for? Is there something easier? is it completely wrong?

http://newzealandmafia.com/files/diagram.png

[Daffyd]

I'm pretty sure you can buy a regulated power supply for this... Jaycar or Dick Smith. Will depend on the wattage as to what size you should get.

[husaberg]

http://www.batteryspace.com/dc-dcregulatormodule13-17vdcto12vdc4ampratewithremovableheatsink.aspx

[Scuba_Steve]

See off the self solutions just aren't as fun are they, there's experience to be missed by simply buying something

[husaberg]

See off the self solutions just aren't as fun are they, there's experience to be missed by simply buying something

Well dig open the jaycar cattledog

http://www.reuk.co.uk/buy-12-VOLT-REGULATOR.htm

[Akzle]

I have a source voltage of 12-14.4v give or take [read car battery], what's the easiest way to ensure this supply is only 12v???
The device I want to use is 12v DC but I'm not 100% it can handle the surge to 14.4v of the charging batt as it was never designed for automobile applications. It was designed for a steady 12v supply

Is the below what I'm looking for? Is there something easier? is it completely wrong?
]

as long as you're aware that that reg has max current handling of 5a, and to actually get near that capacity you'll need one helluva heatsink. Possibly a fan.
.dont know who specd those caps but presumably they know what they're on about. Cant really tell from the pic but i'd be using smoothing caps on the output side, too.

[jonbuoy]

Caps in that circuit are only needed if your charging the battery at the same time as draining it. Better off with a switching DC to DC converter - they need a bit more circuitry but are a lot more efficient. Those linear regulators pretty much turn the excess voltage into heat. They get really hot and waste power. You can buy cheap DC to DC switching converters all over the Internet.

[Akzle]

Caps in that circuit are only needed if your charging the battery at the same time as draining it. Better off with a switching DC to DC converter - they need a bit more circuitry but are a lot more efficient. Those linear regulators pretty much turn the excess voltage into heat. They get really hot and waste power. You can buy cheap DC to DC switching converters all over the Internet.

or, run two of those circuits in parrallel with a 555 and voltage divider for a pwm controller...

[jonbuoy]

If you need more than an amp I would go to your local marine chandlery or solar charging place and ask them if they have any DC to DC converters. The marine 12v isolated ones can usually take from 10-18 volts in and spit out 12v up to 5 amps. Quite efficient but will probably kick the arse out of $100 or more.

[Scuba_Steve]

as long as you're aware that that reg has max current handling of 5a, and to actually get near that capacity you'll need one helluva heatsink. Possibly a fan.
.dont know who specd those caps but presumably they know what they're on about. Cant really tell from the pic but i'd be using smoothing caps on the output side, too.
I need 3A max


Caps in that circuit are only needed if your charging the battery at the same time as draining it. Better off with a switching DC to DC converter - they need a bit more circuitry but are a lot more efficient. Those linear regulators pretty much turn the excess voltage into heat. They get really hot and waste power. You can buy cheap DC to DC switching converters all over the Internet.
We'll it's in a cage so there will be drain & charge on the batt almost constantly


If you need more than an amp I would go to your local marine chandlery or solar charging place and ask them if they have any DC to DC converters. The marine 12v isolated ones can usually take from 10-18 volts in and spit out 12v up to 5 amps. Quite efficient but will probably kick the arse out of $100 or more.
That cost is something I'm wanting to avoid... not the time of year for disposable cash moneys (tho with a new family no time of year is :weep: )

[Akzle]

I need 3A max

That cost is something I'm wanting to avoid... not the time of year for disposable cash moneys (tho with a new family no time of year is :weep: )

:o what did you do to the old one??

:ar15:



3a will still need to be bolted and thermal pasted to a good chunk of ally.

[jonbuoy]

I need 3A max


We'll it's in a cage so there will be drain & charge on the batt almost constantly


That cost is something I'm wanting to avoid... not the time of year for disposable cash moneys (tho with a new family no time of year is :weep: )

For 3 amps your better off with a switching version. Those little linear regulators will get scorching hot. Sometimes you can get cheap universal power supplies that have a cigarette plug to take 12v in they usually have switch on top to change the output voltage. Most of the ones you find are geared up for laptops and won't go lower than 15v. I did pick up a couple a few years ago that would go down to 12v. Worth a punt.

[bogan]

What does it actually supply? If it's not mission critical, and not going to need 3A all the time, you could try just putting a few regs in parrallel, common heatsink with thermal fuse.

[Scuba_Steve]

What does it actually supply? If it's not mission critical, and not going to need 3A all the time, you could try just putting a few regs in parrallel, common heatsink with thermal fuse.

LCD screen - 3A/36W is max, given that this figure is also to drive the TV component I won't/can't use I don't think I'll be at that figure.

I did find this on aliexpress which is in my price range http://www.aliexpress.com/item/Free-shipping-LM2596-Power-Module-DC-DC-Buck-Converter-Step-Down-Module-LM2596-High-Quality-Wholesale/32363769998.html

[Laava]

79c incl postage! Gotta love the chineses! I have bought a shitload of electronic components from them over the last year and have been well happy with every deal. For example I bought 300 high power 3mm leds for less than $9 delivered. The equivalent in NZ was around $1.50 ea at a cheap price!

[bogan]

You might find the LCD screen is fined up to 14.4V, the ones we use have internal LDOs for the logic/comms circuitry anyway, and just run the backlight off the supply (which is through PWM anyway).


79c incl postage! Gotta love the chineses! I have bought a shitload of electronic components from them over the last year and have been well happy with every deal. For example I bought 300 high power 3mm leds for less than $9 delivered. The equivalent in NZ was around $1.50 ea at a cheap price!

I've found some of their stuff isn't that flash on living up to specs. High power being some of the trigger words. Helps to get some known good shit from digikey or similar to compare with. Compared similar for LED strip though, 5m delivered was about the same price as 30cm local :laugh: So with the money saved I bought 5x what I needed, and some RGB indivdually programmable RGB strip. Money was not saved :whistle: