On 1/21/2012 6:41 AM, spamtrap1888 wrote:
On Jan 20, 2:26 pm, wrote:
On Thu, 19 Jan 2012 10:07:50 +0800, Rheilly Phoull









wrote:
On 1/19/2012 6:55 AM, Chas wrote:
I plan to use a ''boombox" in my vehicle because the existing sound device
is defective and next to impossible to remove.
My boombox uses 6 AA batteries...would it be safe to just run a plug from
the 12v cig lighter to a power plug on the boombox? I imagine I will need
some sort of voltage reducer. Anyone got any ideas on how one could build
such a reducer. I am fearing such a device may induce noise.
. . . . .I am of an understanding that 1.5v batterys are acutally 1.2v. Is
this correct? If so, I could run the 12v car voltage to 10 AA batterys and
then tap off six batterys....
Else, if the AA's are truly 1.5 volts then run the 12v car power to 8 of the
AA's and tap off 6.
any help would be greatly appreciated.. . . chas

Just search for "three terminal regulator" until you find a circuit for
the 9volt one. This is a very simple circuit and easy to build, I have
had such in use for years in my vehicles. You can build it in a small
diecast box which would be strong and act as a heat sink for the regulator.

Rheilly P

To expound on this idea, the xx1084 family of regulators would be
ideal. Specifically, the AP1084TL-U adjustable regulator. Datasheet:http://www.diodes.com/datasheets/AP1084.pdf. It's capable of putting
out 5A and has thermal shutdown.

The parts list is simple - An AP1084TL-U, 2 ea 100µF, 25volt caps, a
120 ohm and a 750 ohm 1/4 watt resistor, the die cast box, and an
insulator - the tab of the AP1084 is at the output voltage.


One problem with using this part is the risk of destroying it as soon
as you start the car: The absolute maximum supply voltage is only 12V,
and the alternator puts out more than 13VDC.

The 7809 has a max input of 40v from memory.

Rheilly P