Regulator shouldn't e heating up like this!

Ok I have a 16x4 LCD screen connected to my arduino and a photo resistor also connected through a voltage divider.

I want to run it at night with me wall wart which provides 9v and 500mA.

After running it for 3-5 mins I felt the regulator and it’s damn hot!

Why is this so?

Have you actually measured the output of your wallwart with the arduino connected
If that measures OK (<12volts) measure the current being drawn by the arduino.

The heat developed by the regulator is (Vwallwart-5) x Iarduino watts
Anything more than around 0.2 will cause the regulator to get somewhat hot since there is no heatsink fitted

Voltage regulators are specified as being capable of quite high input voltages and high output currents but these only apply if adequate cooling facilities are provided. Without a heat sink you can have reasonable voltage drop but only at very low currents.

If voltages and current are reasonable you could try adding a heatsink to the regulator

jack

jackrae:
Have you actually measured the output of your wallwart with the arduino connected
If that measures OK (<12volts) measure the current being drawn by the arduino.

The heat developed by the regulator is (Vwallwart-5) x Iarduino watts
Anything more than around 0.2 will cause the regulator to get somewhat hot since there is no heatsink fitted

Voltage regulators are specified as being capable of quite high input voltages and high output currents but these only apply if adequate cooling facilities are provided. Without a heat sink you can have reasonable voltage drop but only at very low currents.

If voltages and current are reasonable you could try adding a heatsink to the regulator

jack

well I ran it with my LCD backlight on and it got very hobut when I turned off the backlight and just had the contrast it got warm but okay.

Yes, but did you [u]measure[/u] the voltage?

AWOL: Yes, but did you [u]measure[/u] the voltage?

nah dont have a multimeter

polishdude20:

AWOL: Yes, but did you [u]measure[/u] the voltage?

nah dont have a multimeter

Then you should purchase one - it is an -invaluable- diagnostic tool for electronics. There are many out there which can be had for very little money (less than $5.00 USD in many cases).

cr0sh:

polishdude20:

AWOL: Yes, but did you [u]measure[/u] the voltage?

nah dont have a multimeter

Then you should purchase one - it is an -invaluable- diagnostic tool for electronics. There are many out there which can be had for very little money (less than $5.00 USD in many cases).

wow less than $5? damn thats a good deal

well I ran it with my LCD backlight on and it got very hobut when I turned off the backlight and just had the contrast it got warm but okay.

Sounds like you haven't got a current limiting resistor in line with the back light. You need one to stop you burning it out.