Get A 5V Dc Output From A Car

[tiv]

Hello everyone,

Bit of an electrical question here,

I've got this BOSE sound kit with IPOD dock gadget , meant for indoor use mainly.. its got audio outs so I can hook up to my sound system,

Seems like it can be very handy on the dash, quite compact slim and looks good too, its got other bits like this voice operation etc

Runs on an adapter from AC power

The required voltage is 5V DC,

I was wondering if there was anyway we could reduce the 12V voltage from a car to 5V, and also bring down the current

I know a bit of electric stuff, but not sure which way to go for this prob, would simply adding resistors sort this out?

Hope an electrical guru can shed some light into this

thanks

[Sifaan]

  On 10/15/2010 at 8:06 AM, tiv said:

I was wondering if there was anyway we could reduce the 12V voltage from a car to 5V, and also bring down the current

I know a bit of electric stuff, but not sure which way to go for this prob, would simply adding resistors sort this out?

A resistor can bring down the voltage, but the voltage drop across the resistor will depend on the current drawn (i.e. if the current draw changes the voltage drop would change) and this could lead to fluctuations that could fry your unit... besides which the resistor will be dissipating all that power as heat.

A resistor / zener diode combo would likely work better (I seem to recall 5.1V Zeners being available)

Depending on whether you're trying to wire it in to the dash, or place it in front of the dash, a lighter socket adapter that provides a USB connection (5v) may also work. Then you need to get a USB connector / cable and wire it to the input of your unit.

[tiv]

  On 10/15/2010 at 8:29 AM, Sifaan said:

A resistor can bring down the voltage, but the voltage drop across the resistor will depend on the current drawn (i.e. if the current draw changes the voltage drop would change) and this could lead to fluctuations that could fry your unit... besides which the resistor will be dissipating all that power as heat.

A resistor / zener diode combo would likely work better (I seem to recall 5.1V Zeners being available)

Depending on whether you're trying to wire it in to the dash, or place it in front of the dash, a lighter socket adapter that provides a USB connection (5v) may also work. Then you need to get a USB connector / cable and wire it to the input of your unit.

Thank you for your reply

I was planning to place in on the dash, Seems the USB cigarette lighter kit thing would work.. the adapter says output - 5V / 2000mA

perhaps I could then simply get a USB cable and fiddle with it so that its joined to the existing adapter jack I have.. Will it work?

[hyacc]

Use an USB charger or build a small circuit using 3 pin LM7805 IC.

[Sifaan]

  On 10/15/2010 at 8:42 AM, tiv said:

Thank you for your reply

I was planning to place in on the dash, Seems the USB cigarette lighter kit thing would work.. the adapter says output - 5V / 2000mA

perhaps I could then simply get a USB cable and fiddle with it so that its joined to the existing adapter jack I have.. Will it work?

2 amps seems a bit much for a device as small as you describe...

I don't know what the rated power for the cig. lighter is - see if you can figure out the fuse that powers it and that should give an indication

but often the device power consumptions is much less than the rated output of the adapter so what you really need to ensure is that the actual power consumption is within the limit of the lighter.

if you can get a unit you can take apart, you can solder the wires into it, without the additional mucking about with a USB cable.

Some car phone chargers will give you 5V, especially if it's a phone that anyway charges off mini/micro USB (such as motorolas, HTC, etc) which will probably be cheaper to get hold of (but will probably be rated for ~600mA only). then you just need to splice the wires

[tiv]

Thanks for you replies guys.. the usb thing worked,

quite handy in the car.. thanks

[devindarocks]

use a mobile phone car charger. it gives 5V output (most of them) just cut the power jack at the wire end and carefully attach it to your device. before that i recomend you to check the output voltage using a multimeter.

[Sylvi]

  On 10/15/2010 at 8:06 AM, tiv said:

Hello everyone,

Bit of an electrical question here,

I've got this BOSE sound kit with IPOD dock gadget , meant for indoor use mainly.. its got audio outs so I can hook up to my sound system,

Seems like it can be very handy on the dash, quite compact slim and looks good too, its got other bits like this voice operation etc

Runs on an adapter from AC power

The required voltage is 5V DC,

I was wondering if there was anyway we could reduce the 12V voltage from a car to 5V, and also bring down the current

I know a bit of electric stuff, but not sure which way to go for this prob, would simply adding resistors sort this out?

Hope an electrical guru can shed some light into this

thanks

tiv' timestamp,

You can buy a electronic part which will cost round Rs 50/00 and use same in seris with your DC circuit then you will get a 5 Volts DC from 12 volts DC. If further details are necessary please request.

Resistance method your current draw has to match with the Resistance.

Silvi Wijesinghe.

Sylvi Wijeinghe.

[rameez]

  On 10/17/2010 at 3:28 PM, Sylvi said:

tiv' timestamp,

You can buy a electronic part which will cost round Rs 50/00 and use same in seris with your DC circuit then you will get a 5 Volts DC from 12 volts DC. If further details are necessary please request.

Resistance method your current draw has to match with the Resistance.

Silvi Wijesinghe.

Sylvi Wijeinghe.

sylvi please do give me the details as i am facing a situation where the car phone charger does not charge my phone even when the cigaratte lighter s fine.

[Sylvi]

  On 6/12/2011 at 3:12 PM, rameez said:

sylvi please do give me the details as i am facing a situation where the car phone charger does not charge my phone even when the cigaratte lighter s fine.

'rameez',

Can you please inform me the amperage (Draw of Current) of your unit you want to use 5 Volts DC.

The car P/Charger may be defective you can buy a car P/Charger for Rupees 200.00 at 1ST Cross Street.

Sylvi Wijesinghe.

[rameez]

  On 6/13/2011 at 1:52 AM, Sylvi said:

'rameez',

Can you please inform me the amperage (Draw of Current) of your unit you want to use 5 Volts DC.

The car P/Charger may be defective you can buy a car P/Charger for Rupees 200.00 at 1ST Cross Street.

Sylvi Wijesinghe.

is a car phone charger so cheap.... ....even in 1st cross street.

the unit is a Nokia phone charger.so the current must be less than 200mA.

When i fix the phone the message says not charging.......

[Sylvi]

  On 6/13/2011 at 4:17 AM, rameez said:

is a car phone charger so cheap.... ....even in 1st cross street.

the unit is a Nokia phone charger.so the current must be less than 200mA.

When i fix the phone the message says not charging.......

'rameez'

Yes Car charges are available 1st Cross street Maliban Street junction on the right hand side one shop before the last they deal only H/P accessories.You have take your phone and the will give you one. I paid for three Rs.450.00.

If you want as one post said by (hyacc).Build a small circuit using 3 pin LM7805 IC.

This IC also can get at Maliban Street.Try any Electronic parts shop say you want to convert 12 Volts DC to 5 Volts DC the will help you with all spares.

Sylvi Wijesinghe.

[Sylvi]

rameez,

I give you the circuit web page.

http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html

[Dinuk]

  On 6/13/2011 at 1:54 PM, Sylvi said:

rameez,

I give you the circuit web page.

http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html

This circuit is not designed to use with the car battery. The 7805 might blow up... But this won't cost more than a Rs50. So it's worth for trying....

[Sylvi]

  On 6/13/2011 at 3:26 PM, Dinuk said:

This circuit is not designed to use with the car battery. The 7805 might blow up... But this won't cost more than a Rs50. So it's worth for trying....

'Dinuk',

I use this circuit for a small drill what I use with DC 12 volts input it had served me for three years.

Sylvi Wijesinghe

[ruwds]

  On 6/13/2011 at 4:17 AM, rameez said:

is a car phone charger so cheap.... ....even in 1st cross street.

the unit is a Nokia phone charger.so the current must be less than 200mA.

When i fix the phone the message says not charging.......

Can you check the original charger output?

Some phones with micro usb charging port requires minimum of 500mA to charge and if less it would say insufficient power etc.

[Dinuk]

  On 6/14/2011 at 2:13 AM, Sylvi said:

'Dinuk',

I use this circuit for a small drill what I use with DC 12 volts input it had served me for three years.

Sylvi Wijesinghe

Do you connect it to your car battery?

Edited June 21, 2011 by Dinuk

[Sylvi]

  On 6/21/2011 at 6:54 PM, Dinuk said:

Do you connect it to your car battery?

'Dinuk',

Yes this circuit is directly connected to car battery .My drill had 4.5 Volts DC with three small penlight batteries I cannot find a 4.5 Volts unit so I used above circuit the drill goes little faster. For three years nothing had gone wrong on the drill.

Sylvi Wijesinghe.

[Dinuk]

That's cool... I tried this 7805 few years back and blowed it up in milliseconds. After that I used a resister to reduce the input current....

[Sylvi]

  On 6/22/2011 at 6:19 PM, Dinuk said:

That's cool... I tried this 7805 few years back and blowed it up in milliseconds. After that I used a resister to reduce the input current....

'Dinuk',

Your usage current is more than the rated current on the circuit handling of 7805 SCR.

Sylvi Wijesinghe.

[mnaka]

  On 6/22/2011 at 11:55 PM, Sylvi said:

'Dinuk',

Your usage current is more than the rated current on the circuit handling of 7805 SCR.

Sylvi Wijesinghe.

Yes 'Dinuk' 7805 regulator is rated to give 1A output so the output must less than 1 amps

[Dinuk]

No, It was just a 555 puls generator.

[mnaka]

Or you could use LM123 3amps, 5v regulator same as 7805

http://www.national.com/opf/LM/LM123.html

[Dinuk]

  On 6/24/2011 at 4:00 AM, mnaka said:

Or you could use LM123 3amps, 5v regulator same as 7805

http://www.national.com/opf/LM/LM123.html

Yes.. this is very useful IC..... thanks for sharing mnaka.... I haven't tried this....