Quick electrical question [Archive]

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MrMelon

15th August 2006, 09:37

I've got an external usb hard drive I want to be able to use in my car. It needs 12v DC and 5V DC @ 2A.

How can I easily get or make up and adaptor that'd let me do this from a lighter socket input?

Cheers

Ixion

15th August 2006, 09:47

You can get universal adaptor kits that have a cigarette lighter adaptor and a range of plugs and "tips" that enable you to select almost any voltage and plug size used on electronic equipment. I got mine at Dick Smith, but I saw similar ones at Repco the other day. You just put in the plug that matches the voltage you need and the tip that fits your device. As you need two voltages you may need to rig a separate feed for the 12v, but that can be direct from the 12V input, just a wee bit of soldering.

Mooch

15th August 2006, 10:02

Also , make sure that the output voltage is regulated. The cars voltage will varry from 12 volts with the engine off to around 13.8 - 14 volts with the alternator charging the battery. Some electronics gear is very sensitive to the voltage and can blow as a result.

Also be extra careful if your running an ICE system as the car voltage can go crazy if your running high volume.

paturoa

15th August 2006, 10:16

does it have its own 230v power supply adapter? - if so get a car 12v to 230 inverter like this

http://www.jaycar.co.nz/productView.asp?ID=MI5120&CATID=8&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=680

Wasp

15th August 2006, 11:28

inverters can be expensive.

imguessing its a standared drive caddy - data on one usb port and power from the other?
im guessing you want it to play music off of it by plugging it into the cars stereo or similiar?

(i think ive seen some adapters (laptop possibly) that have a usb power port on them aswell as their intended power cable - saying that a 12v cigerate lighter shouldnt be hard to convert into a usb power - I DONT KNOW THE SPECS FOR USB SO DO NOT BLAME ME IF IT BLOWS UP

*picks up laptop usb drive caddy from desk* "hmmmmm......"

thinking of that, a laptop usb drive caddy and hdd would be a more suitable size too ;)

MrMelon

15th August 2006, 13:45

The plug I need to use for the usb enclosure is pretty similar to a ps2 plug
<img src=http://img.shopping.com/cctool/PrdImg/images/pr/177X150/00/01/4a/a1/f3/21668339.JPG>

The top 2 pins are 12v, the left 2 are ground and the right 2 are 5v. I've already got an inverter but don't want to have to lug around an inverter as well as the bulky power supply that came with the usb enclosure, just wanted to replace the whole lot with a nice little plug that goes straight into the lighter socket.

Ixion's idea sounds like it'd be pretty close to what I need, but I don't think there's any widely available plug that would fit my specs, so I think I might need to custom make one.

Is it difficult to regulate the ouput voltage from 13-14v to a solid 12v, then split it down into 12v and 5v from there? I can pick up a cheap lighter plug from jaycar and could probably track down the power connector I need, I'm just not sure of what needs to be done in between!

Cheers

sAsLEX

15th August 2006, 13:48

Is it difficult to regulate the ouput voltage from 13-14v to a solid 12v, then split it down into 12v and 5v from there? I can pick up a cheap lighter plug from jaycar and could probably track down the power connector I need, I'm just not sure of what needs to be done in between!

Cheers

Not really just get a beefy voltage regulator and whack a heatsink on the back.

http://www.dse.co.nz/cgi-bin/dse.storefront/44e127fc064ad36e2740c0a87f990717/Product/View/Z6561

Ixion

15th August 2006, 13:50

MrMelon

15th August 2006, 14:26

Cheers for that.

How do you split it down into 12v and 5v again after regulating it to 12v?

Wasp

15th August 2006, 14:35

bungbung

15th August 2006, 14:39

You can buy fixed output voltage regulators, LM7805 and 7812 (+5 and +12V). Their max output current is 1A, which might not be enough for your requirements.

Straightforward to wire up, but they'll need a suitably large heatsink, especially the 5V regulator.

paturoa

15th August 2006, 14:43

I'd still go for the inverter about $60, a whole lot less shaggin around, will have a warranty and if u change your mind u can plug other stuff in too.

MrMelon

15th August 2006, 14:44

You still didnt answer what you want it for.

if i were to do it for an external drive for a car stereo i'd use a laptop hdd ($100ish depending) and a usb laptop drive caddy (one usb port on the computer used for data, the other for data. id use something like this: http://rogerssystems.com/store/images/TM-USB-PLG.jpg to power the caddy (i dunno if thats available here, i just googled for it)

Nobody asked what I wanted it for!

You can get these head units off trademe for about $100 that have a usb port in them that you can ply mp3s from. I bought a 2 gig usb stick the other day but lost it within a week so figured I'd get an external enclosure and cheap IDE drive to fill up with mp3s and whatever so I can have my entire music collection in the car and play it through the stereo easily.

I've already got the external enclosure and drive, all I need is a nice easy way to power it straight off the lighter socket without having to go through an inverter and then regulate it down from 230-12v again.

The specs on the power supply brick that came with the enclosure say it outputs 2000mA on the 12v and 5v pins. A hard drive spinning up would probably use all of that, but cheers for the suggestion :D

Wasp

15th August 2006, 14:53

I did ask, look up a bit :nya:

Remember also that you will need to mount the hdd properly and set up a shock absorbation system otherwise it'll be shagged within the month (or sooner) from the bumps. also youll need a switch to flick it off when its not in use, a spinning hdd is ALOT more delicate than one that isnt - could be as simple as going over a pothole or speed bumps.

main reason i'd use the laptop hdd/caddy is it'll easily fit in your hand, caddy is only $20

MrMelon

15th August 2006, 14:56

Can you put those 1A regulators in parallel to put out 2A or is that a no-no? What about running the adjustable 12V 3A regulator at the start? I guess it would restrict the current available to the rest of the circuit after that to 3A max?

MrMelon

15th August 2006, 15:05

The drive enclosure has its own power switch on it so that's not a problem. I'm sure I can make up a little foam filled compartment for it to sit in.

I don't need anything that fits in my hand, its for use in my car! A 300gb 3.5" ide drive is about $150, the biggest 2.5" drive you can get is around 160gb and they're over $400... It wasn't a hard decision to go for the 3.5" enclosure!

bungbung

15th August 2006, 15:18

The 1A regulators would cope with an overload for the duration of the spinning up, come to think of it, you would be best to run the requlators in parallel:

Without measuring the spinup current, it would be safer to use the adjustable 3A versions instead, they will require a few extra components.

sAsLEX

15th August 2006, 15:19

12V supply to two seperate VR's like I linked to then you have a 12V up to 3A and a 5 Volt up to 3 A as well.

MrMelon

15th August 2006, 16:07

Cheers for the help guys.

I'll try running the 12v line unregulated and just regulate the 5v 3A one first and see how that works. Might pay to put the old 4 gig drive I don't care about in for the testing though!

aff-man

15th August 2006, 16:16

this what you sorta looking at?
http://www.dse.co.nz/cgi-bin/dse.storefront/44e127fc064ad36e2740c0a87f990717/Product/View/H3490
http://www.dse.co.nz/cgi-bin/dse.storefront/44e127fc064ad36e2740c0a87f990717/Product/View/Z6561

Wasp

15th August 2006, 17:09

I don't need anything that fits in my hand, its for use in my car! A 300gb 3.5" ide drive is about $150, the biggest 2.5" drive you can get is around 160gb and they're over $400... It wasn't a hard decision to go for the 3.5" enclosure!

And your going to listen to all 300gbs of music everyday? (i hope for your sake its REALLY high quality music :nya:

Helps if you work for a company that deals in laptops :innocent:

MrMelon

15th August 2006, 17:20

I like having options and being able to load it up with movies and things. Don't make me set Helen onto you!

MrMelon

15th August 2006, 17:23

Str8 Jacket

15th August 2006, 19:20

Don't make me set Helen onto you!

GRRRRRR!!!! Be afraid.... Be VERY AFRAID!!!:stoogie: