# How to build a 1,5V power supply???

Discussion in 'Electronic Basics' started by E Draisma, Aug 25, 2003.

1. ### E DraismaGuest

Hi there,

For an art project I need to build a small 1,5V power supply to power a
small MP3 player. (replace a 1,5V AA battery)
Available is 8-10V DC.

I know a little bit about electronics, enough to build a simple schematic.
However, I can't find a schematic to do this; maybe anyone of you knows how
to do it?

I would be very pleased if anyone could help me!

Eibert Draisma.

2. ### Costas VlachosGuest

.. ___ Imax
.. 8-10V o-------|___|------o------>-----o ~1.4V
.. R |
.. |
.. |
.. V 1N4001
.. -
.. |
.. |
.. V 1N4001
.. -
.. |
.. |
.. ===
.. GND

Should work with a battery-powered device such as your MP3 player. The value
of R depends on the player's maximum current demand, Imax. Use the equation:

R = 5V / Imax

where 5V is the voltage drop across R caused by Imax alone. This will keep
the diodes on when I <= Imax, so as to maintain about 1.4V across them.
Values higher than 1 kOhm may result is output voltages of less than 1.4V.

Not the best solution in terms of regulation, but easy to build and should
work for this application.

cheers,
Costas

3. ### Guest

You could replace the resistor with an filament bulb. This would
convert some of the energy to light and reduce the heat. It would also
tend to series-regulate because its resistance increases the hotter it
gets i.e. the more current you try to draw.

Robin

4. ### WayneGuest

It really only uses a single 1.5v battery?

5. ### sineGuest

It looks like a FET transistor, is it ?