Dangle_kt
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| posted on 21/10/07 at 11:20 AM |
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Battery to cigerette lighter adaptor
hi guys,
power lead plug thing snapped off from my sat nav the other day. means it can only be powered by 4 aa batteries now - problem is that only gives it
about 15 mins use.
can you buy an adaptor which looks like 4 aa batteries, but has a lead that you can plug into the cigerette lighter to supply constant power?
i tried finding one, but i dont know much about electrics!!
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stevec
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| posted on 21/10/07 at 11:33 AM |
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I am confused.
How do you get 12v from 4aa batteries ?
Steve.
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Dangle_kt
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| posted on 21/10/07 at 11:37 AM |
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I dunno...
basically it had a plug in the bottom to allow it to be powered via a mini usb lead that plugged into the cigerrette lighter socket.
that snapped off inside the unit.
it also has a panel on the back to allow the unit to be powered by 4x aa batteries. this is now the only means i can power the unit - BUT the
batteries only power the unit for about 15mins before they die. i need to use the panel on the back that holds 4xaa battereies but some how wire it up
so it can be perminantly powered by the cigerette lighter.
does that make more sense now?
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Dangle_kt
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| posted on 21/10/07 at 11:42 AM |
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like this
[img][/img]
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billynomates
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| posted on 21/10/07 at 11:58 AM |
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My sat nav works at 5v DC. So I assume yours is similair, hence only needing 4 aa batteries.
Could you not connect the battery terminals together with wires +ve to -ve, then connect the wires from the plug in adaptor to the first and last
battery terminal.
You need to make sure that the plug in lead has a transformer in it though to reduce the power down to the correct voltage.
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hobbsy
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| posted on 21/10/07 at 12:03 PM |
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Yeah it will be 5V on the mini USB as per the spec.
so 4x rechargeables = 4x1.2v = 4.8v OR
4x normal batts = 4x1.5v = 6v
You could use your existing adaptor by cutting the mini-usb plug off and wiring it to the battery connections - just use the two outer ones AND
definitely check and DOUBLE CHECK the polarity with a multimeter else you might blow up your sat nav (if its not polarity protected).
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Dangle_kt
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| posted on 21/10/07 at 12:07 PM |
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could i trouble anyone for a circuit diagram of what they mean? it would really help me as i aint good at electronics. thanks!
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Grimsdale
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| posted on 21/10/07 at 12:09 PM |
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yo can get dummy AA batteries from places like maplins, and you could solder in wires to provide power, but you'ld still need to change the
voltage down to 6v.
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BenB
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| posted on 21/10/07 at 12:46 PM |
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If they're rechargeable batteries then they're 1.2v each so 1.2v * 4 = 5v.
I'd use one of these
http://www.maplin.co.uk/Search.aspx?criteria=L17AR&DOY=14m10
set to 5v
and two dummy AA batteries (available somewhere from Maplins).
Put the two dummy batteries at either end of the battery pack
ie Bat - empty - empty - Bat
Chop the end off the regulator, use a multimeter to find out which is the +ve lead. This goes to the +ve nipple end, the negative goes to the flat
battery end.
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gingerprince
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| posted on 21/10/07 at 12:46 PM |
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quote:
Originally posted by Dangle_kt
could i trouble anyone for a circuit diagram of what they mean? it would really help me as i aint good at electronics. thanks!
You need to determine (with a multimeter) which terminals of your battery compartment want the 6 volts. The batteries will be connected in series,
with metal terminals joining adjacent batteries +/- terminals. Use a tester accross adjacent +/- to determine which ones are connected together (as
per diagram below - unless you can see through gaps in the casing). From that you'll be able to determine which end-points aren't
connected, and therefore which need your 6 volts.
 
AA Batteries
Once you know the correct +/-, chop your miniusb off your old charger and solder to the correct terminals.
Disclaimer: Of course only do this once you're confident you have the correct terminals and know what/why you're soldering what to what.
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tks
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| posted on 21/10/07 at 01:09 PM |
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if you want it locost
you could just buy an LM7805
and a cigaret lighter plug.
Also i would solder in 2 caps.
then you are done for the minimum amount of money.
1 cap 100uF 10p
1 cap 10uF 10p
1 7805 60p (for 6 volts 7806)
1 cigaret lighter plug (halfords) 3pounds??
piece of cable and just solder it hard to the batterybox terminals.
Will deff work.
The above comments are always meant to be from the above persons perspective.
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MkIndy7
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| posted on 21/10/07 at 03:19 PM |
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Can't you judst dig out the piece of connector thats stuck in, and get a new lead?
Surely that would be alot less messing about and easier than finding an alternative.
Maybe if you open up the sat-nav it'll make it easier to dig it out.
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Dangle_kt
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| posted on 21/10/07 at 04:51 PM |
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quote:
Originally posted by tks
if you want it locost
you could just buy an LM7805
and a cigaret lighter plug.
Also i would solder in 2 caps.
then you are done for the minimum amount of money.
1 cap 100uF 10p
1 cap 10uF 10p
1 7805 60p (for 6 volts 7806)
1 cigaret lighter plug (halfords) 3pounds??
piece of cable and just solder it hard to the batterybox terminals.
Will deff work.
this seems a good option, as i have the cig lighter plug and can use the cable off it...but can you draw a diagram of how you would order the
regulator and capasitors please?
thanks!
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gingerprince
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| posted on 21/10/07 at 06:57 PM |
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You usually get example circuit diagrams with semiconductor datasheets. See Figure 5 below: -
www.ortodoxism.ro/datasheets/fairchild/LM7805.pdf
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tks
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| posted on 21/10/07 at 07:08 PM |
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page 21 fig 8.
i would place the big cap on the input.
and the smaller on on the output.
that way if you play with the plug, the device wont easy resets because of lack of power.
i would also mount all the chips and crisp in the plug. it will fit if you do your best.
sow it will be then an nice install.
on the other side of the plug cable you could solder the USB lead. and just power it using the USB plugin thing. that way your device will keep a bit
neathier etc.
The above comments are always meant to be from the above persons perspective.
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Dangle_kt
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| posted on 5/11/07 at 09:06 PM |
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Thanks for the help from everyone - here is an update:
 
Sat nav fix
It's doen and working!
I bought a multimeter, hot glue gun, soldering iron and varible voltage car charger thing.
Figured out - + polarity, voltage of batteries vs voltage from car charger, then fitted a few block connectors onto the wires, glued them in place,
soldered the - and + to the - and + on the sat nav unit and job done!
It works a treat, and with the rear panel refitted you can hardly tell it isn't meant to be powered that way!
I'm well chuffed! my first atempt at anything electrical, that didn't involve calling the fire brigade!! 
Bought a little project from maplin to try and improve further - though my soldering will need to be a little better for it to work.
Maplin was great, like an aladins cave of goodies, and very helpful staff! A good day all round 
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Macbeast
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| posted on 5/11/07 at 10:22 PM |
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Maplin and helpful staff in the same sentence ???
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Dangle_kt
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| posted on 6/11/07 at 08:55 AM |
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quote:
Originally posted by Macbeast
Maplin and helpful staff in the same sentence ???
I had my 10 week old son with me, the car seat was heavy, so when I arrived at desk with a multimeter (that was on BOGOF deal) they went and got my
free one, I didn't even ask, they mentioned it.
Pretty good if you ask me.
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