Author Topic: Linear Regulated Power Supply with LM317T & MOSFET 50N06  (Read 24146 times)

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Offline MMDuinoTopic starter

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #25 on: April 20, 2015, 10:09:21 am »
i have used (12v 1 Amp bulb) and (12v 1.3 Amp - motor), and it's works normally, i have got full 6Amp passes through MOSFET and 12v regulated.  :-+

I know very well the MOSFET behavior almost same with (thyristors & AC voltage), but i don't know :-// practically its works well here...
Works well??? Then try to measure load regulation of this junk.
 

Online wraper

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #26 on: April 20, 2015, 10:14:15 am »
i have used (12v 1 Amp bulb) and (12v 1.3 Amp - motor), and it's works normally, i have got full 6Amp passes through MOSFET and 12v regulated.  :-+
Works normally? Did you even measure the voltage at all?
Use no load, 10mA, 100mA and 3A loads, for example. Then measure how stable is voltage with the load changing. What you wrote is just plain stupid in assessing if it works well. "motor is rotating, must be a damn good circuit:palm:
« Last Edit: April 20, 2015, 10:18:50 am by wraper »
 

Offline MMDuinoTopic starter

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #27 on: April 20, 2015, 10:21:33 am »
Dear Hero

i tried already to do this circuit with PNP transistor (BD244C) but i got low current at the output when i was trying to put 3 Amps load on the out output i've got overheating on LM317T, that's what happened with me practically.


As I said before, there's no point in adding buffer after LM317.

Here's the correct way to increase the current capacity of the LM317.

When the current through the LM317 exceeds about 60mA, Tr1 starts to conduct, diverting the current round the LM317.

This circuit has its shortcomings: mainly being the lack of short circuit protection, but this can be added fairly easily if needs be.
 

Online wraper

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #28 on: April 20, 2015, 10:33:35 am »
Dear Hero

i tried already to do this circuit with PNP transistor (BD244C) but i got low current at the output when i was trying to put 3 Amps load on the out output i've got overheating on LM317T, that's what happened with me practically.

First of all BD244 is not powerful enough for 3A current. Secondly LM317 will pass part of the current through itself, therefore needs to be on the heatsink too. If you have for example 24V on the input, and 1V on the output and 3A current, that will mean 23*3 = 69W of power dissipated on pass element (transistor+LM317). Exactly the same if using MOSFET as in your circuit, just that LM317 is not passing any significant current.
 

Online Zero999

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #29 on: April 20, 2015, 10:43:20 am »
Dear Hero

i tried already to do this circuit with PNP transistor (BD244C) but i got low current at the output when i was trying to put 3 Amps load on the out output i've got overheating on LM317T, that's what happened with me practically.
What was the input/output voltage?

What was the value of R3?
 

Offline MMDuinoTopic starter

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #30 on: April 20, 2015, 10:45:34 am »
Could you please explain what will happen here, cause as i said before i'm just beginner technician and up to now i can't understand the PWM signal as i think its applied here in your circuit..

Quote
practically it's works well.
Yes, as I sayed. As long as the MOSFET has a voltage at its gate, it will do something. But it is far of controlled in any way.
Here is a very simple circuit for voltage regulation.

Edit: You can also use your N-cannel MOSFET, it just requires to flip things around here and there.

The LT1009 is a voltagereference. You don't essentially need it, instead you can use your LM317, even if it is not the best reference.
 

Online Zero999

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #31 on: April 20, 2015, 10:50:46 am »
Could you please explain what will happen here, cause as i said before i'm just beginner technician and up to now i can't understand the PWM signal as i think its applied here in your circuit..
It's a linear regulator. There is no PWM signal.
 

Offline MMDuinoTopic starter

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #32 on: April 20, 2015, 11:01:12 am »
So why there is 1000n+1k for feedback with negative input of LM324, it will work as a noise generator or something like that???

Could you please explain what will happen here, cause as i said before i'm just beginner technician and up to now i can't understand the PWM signal as i think its applied here in your circuit..
It's a linear regulator. There is no PWM signal.
 

Online Zero999

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Re: Linear Regulated Power Supply with LM317T & MOSFET 50N06
« Reply #33 on: April 20, 2015, 11:13:51 am »
So why there is 1000n+1k for feedback with negative input of LM324, it will work as a noise generator or something like that???
It's a frequency compensation network to stop it oscillating.
 


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