5v Regulated power supply for the robots microchips(PIC)'s and sensors.

The PIC's and sensors etc. are all powered from a 5v regulated power supply.
The power for the 5v regulator comes from a 9v battery, either a PP3 or PP9.
The circuit is based on the one described in Intermediate Robot Building which is based around a 7805 5v regulator, shown below.

 5v regulated power supply schematic.

Full size schematic.

 5v regulated power supply circuit

A DPDT switch is used to dissipate any current stored in the capacitors, through R1 & R2 to 0v when the robot is switched off. A fuse is also added for extra protection from over current, which in the past this has proved very useful.

As I have added more sensors, the 5v regulator is not coping very well maintaining 5v, even with a fresh 9v PP9. With all sensors running the 5v drops to just over 4v in no time at all.

So I am now in the process of building a better 5v supply that uses less battery power to maintain 5v. This circuit is also described in the book Intermediate Robot Building . More later.

Note the use of PCB turned pin sockets for all wire connections and PCB sockets for 5v regulator.

Devices and wires can be easily changed using this method.




UPDATE - Testing a 2940 low dropout 5v regulator.
I've swapped a standard 7805 with a 2940 5v regulator.
Input			Device			Output(v+)		Output(v-)
9v(9.36)		2940			4.98v			0.00v
6v(6.05)		2940			4.97v			0.01v
9v(9.41)		7805			5.01v			0.00v
6v(6.04)		7805			4.22v			0.00v

These voltages are at the output of the 5v regulator, without circuits connected. With the circuits connected I'm getting a reading of 4.96v, (2940 + 9v PP9) which is far better than the standard 7805 5v regulator. Ideally I'd like to use 6x1.2 rechargeable's(7.2v). The circuit described here, also uses a FU5505 MOSFET, instead of the 1N5817 diode, but I've been unable to obtain one as yet. If I can get the circuits working OK with the rechargeable's, I won't bother with the MOSFET, as they do use a lot of current to work.



 5v regulated power supply circuit, with controls attached.

5v regulated power supply circuit, with controls attached.