# how to determine operating temperature of diode ?

Discussion in 'Homework Help' started by abhimanyu143, Jun 2, 2015.

1. ### abhimanyu143 Thread Starter Member

Aug 25, 2014
211
1
Hello
how to determine the temperature of diode during working condition ?
1. diode
2. capacitor
3.regulator Ic
4. resistor
5. LED
6. battery

I have connected all component on breadboard

2. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,070
Learn how to post a schematic diagram

3. ### Jony130 AAC Fanatic!

Feb 17, 2009
4,167
1,188
In diode datasheet try to find a Thermal resistance between junction to ambient (Rthja).
Next find diode forward current If and diode forward voltage drop Vf and find the power dissipation in the diode Ptot = If * VF. And finally find diode junction temperature Tj = Tambient + Rthja*Ptot.

Aug 25, 2014
211
1

5. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,070
What does the upright triangle symbol represent? A power supply?
Are you expecting that temperature effects D1, and somehow that is going to effect the voltage output of the regulator?

Hint: Even if the diode had an effect on the voltage at pin 1 of the regulator, the regulator is specifically designed to ignore voltage fluctuations at its input, so what are you trying to accomplish?

6. ### Jony130 AAC Fanatic!

Feb 17, 2009
4,167
1,188
Yes, this is normal for Proteus vsm.

7. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,070
And what is the voltage?

8. ### abhimanyu143 Thread Starter Member

Aug 25, 2014
211
1
I am using 9 v dc battery. actually I am trying to do some analysis my self by doing some practicals step by steps

9. ### ErnieM AAC Fanatic!

Apr 24, 2011
7,906
1,789
The diode where it is will help protect you if you plug the battery in backwards, which is quite easy to do with a 9V battery.

Mike gave you the start of figuring out (well, estimating) the temperature of the diode. Don't forget the 7805 will waste some current (typically called quiescent current) that never makes it to the load so there are two sources of current out of the diode: load and regulator.

10. ### wmodavis Well-Known Member

Oct 23, 2010
739
150
Learn to read and understand the manufacturers data sheet. That is what it is for - to help you understand the component and use it properly so it will have a long and happy life.