-5V

how to get a -5V (Vee) for a LCD if i only have a power supply.it need a +5,-5 and gnd.

thanks

you can get voltage inverting chips

Maxim and others make the converter chips like Styx described. They're very easy to use, just the chip and a couple of capacitors. ICL7660 and MAX1440 are some part numbers. Here's a link to the datasheet:https://www.electro-tech-online.com/custompdfs/2004/07/ICL7660-MAX1044.pdf
JB

For LCD negative voltage you really need very little current.
Take a look at this is you are comfortable with 555 chips
http://www.csgnetwork.com/ne555c1.html

+,-,5v power supply

u can use a simple circuit using two ics ic7805 and ic7905. The input will be more thn 5v say 9volts dc.and output u will get is +5,-5 and Ground.
can u find the circuit in Linear Integrated Circuit Book.

as well as the circuits described above, you can use a 555 timer with a rectified output, or look at this page: **broken link removed**

Tim

If you are planing on using power supply, you can make it anything
you want but if you are planing on using single power source
like battery it all really depends on how accurate the -5V has to be.
Check the datasheet. Normally the negative voltage should
not be critical, it's only for contrast of the display so I would
not be surprised if it works with anything between -3 and -5V.
If you plan on powering your device from 9V battery, you might
try to use circuit bellow. It will give you regulated +5V.
The difference is the negative voltage Vneg=5V-Vbatt.
For example if your battery drops to 8.6V, negative voltage would
be Vneg=5-8.6=-3.6V. Check the datasheet and see if you are
lucky...