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heating problem lm317, lm2576 5v, 7805

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hi
i working on some project and facing problem with all regulator(lm317, lm2576 5v, 7805)

i am using AT89s52 + HC05(Bluetooth module) + solenoid valve
my task is simple on/off solenoid valve via bluetooth through android app.

micro-controller works upon 5v and solenoid valve operates on 24v. problem is, the regulator :-x
i have used lm317 , lm2576 5v ,7805 with proper heat sink on 24v dc adopter. each and every regulator as mentioned, is heat up within short time period. :???:

i know about power drown will be heat up the regulator but when i only connect Bluetooth with lm2576 5v, its still heating up.

needed help to sort out this .

thanks in advance :)
 

Hi..

In your power supply design almost 19 Volts droped across the regulator. So its automatically disipate the power via heat.

You reduce the input voltage of the regulator or connect the 47 ohm or less 5 Watt (1 or 2)resistor series with the regulator for better results.

And also Post your maximum load current.

I hope its helps you
 
thanks amayilsamy

i didn't check the power consumption, but i m trying with 470 ohm/2W
and also check the power consumption .

thanx again
 

yes you should consider current and voltage you are giving. Give less voltage and current it will not get heated.
 

Your solenoid valve will draw 3 to 4A and the regulators can't withstand that much current. Connect 24V DC unregulated to solenoid and use a LM317T to get 9V out and connect this to 7805 input. 7805 will power the MCU. Use a 2N3055 transistor or IRF840 MOSFET to drive the solenoid.
 

milan.rajik said:
Your solenoid valve will draw 3 to 4A and the regulators can't withstand that much current. Connect 24V DC unregulated to solenoid and use a LM317T to get 9V out and connect this to 7805 input. 7805 will power the MCU. Use a 2N3055 transistor or IRF840 MOSFET to drive the solenoid.
Click to expand...
i am using as you said, solenoid valve with 24v unregulated supply
and tested this before posting thread:- lm317 ==> 7805==> micro controller. now lm317 and 7805 also heat.

conclusion:- total heat of 7805 now divided into lm317 and 7805.

i am using TIP122 and 817 opto-coupler to drive solenoid valve
 

Hey It will be helpful if you share the schematic. Are you using AC power or Battery supplied DC power. I will assume that you are using AC power.As mentioned above if you are dropping more voltage more heat will dissipate. Simple solutions is use of multi tapped transformer. use the taping of 12 V to generate 9V DC and use taping of 8 V to get 5V DC. and 26 v to get 24v DC.
Also use following measures.
[1]check the diode you have connected o LM2576 it should be 1N5822 or similar
[2] check caps values connected across LM317 and 7805
-Shivam K
 

Why are you using LM317 and 7805? Is LM317 a part of battery charging circuit ? Please post the schematic.
 

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