Is your circuit built on a breadboard? Breadboards can have unreliable contacts.

No I soldered them.

 

Did you get those voltage readings?

 

Did you get those voltage readings?

I checked... Gate to ground voltage is the same as the input supply voltage 13 Volts DC without any pwm.

Let me know if any other voltage or current reading needed to be checked.

 

Then the mosfet should be OFF.
If it's still ON and its not shorted then the Source and Drain are reversed.

 

Then the mosfet should be OFF.
If it's still ON and its not shorted then the Source and Drain are reversed.

Anyways I am soldering a new circuit with another spare MOSFET. I will let you know.

 

Post a clear photo of the circuit so I can see the connections on the mosfet.

 

Post a clear photo of the circuit so I can see the connections on the mosfet.

Ok I will post. But I remade the circuit, the same problem persits. I dont think the zero PCB board and its soldering connections will be clear. Also soldering an SMD MOSFET seemed to be a challenge. I am not an experienced circuit maker BTW.

I have done continuity tests for short circuit it is all fine.

 

hi sab,
I have cleaned up your images, also flipped the copper side to show it looking through the PCB, makes it easier to check the tracks.
E

 

I dont think the zero PCB board and its soldering connections will be clear.

Yeah that's pretty much impossible.
Label those 2 green connectors on the board. Which one is the power supply and which one is for the load.
Show which pins are negative or ground and which pins are positive.

 

Ok I have labelled them.

 

 

In the post#47 pic it looks as though there might be a tiny blob of solder shorting two pins of the FET.

 

In the post#47 pic it looks as though there might be a tiny blob of solder shorting two pins of the FET.
View attachment 362753

Yeah I checked it, its not shorting.

 

You want me to connect the drain to the + of the Load and source to + of the Supply?

That is not how it is in the circuit

 

You want me to connect the drain to the + of the Load and source to + of the Supply?

Yes and the schematic is correct but you have the labeled the mosfet incorrectly.
See the symbol below.

Now configure the circuit as shown, pleassssssse.

 

Yes and the schematic is correct but you have the labeled the mosfet incorrectly.
See the symbol below.
Now configure the circuit as shown, pleassssssse.

sghioto,

Yes... That is correct. I made a mistake...

Thanks a lot for correcting it...

I will reconfigure the circuit and post it. It ll take some time....

 

Yes that was the mistake. Now its working fine. Thanks for helping out.

I have connected a resistor in parallel with the MOSFET switch terminals. I have set the current to 1.4 Amperes when the switch closes and 0.7 Amperes when the switch opens(current flows through the resistor). Now this is what I get at 0.1 Hz. 5 seconds MOSFET is ON followed by 5 seconds OFF PWM signal.

Still there seems to be little bit fluctuation but it is much lesser than when I used the readymade module.

Here is a link to the video:

https://drive.google.com/file/d/15Lqihrc3TKwFlmBIarrteK4JjqTZO1ad/view?usp=drivesdk

 

What is the resistor value used to test with?
Does the supply voltage remain steady during the test?

 

What is the resistor value used to test with?
Does the supply voltage remain steady during the test?

Its ok sghioto, the current is steady (while swiching) after I increased its value. Now it is 1 Ampere low and 2 Ampere high.

The supply is from a constant current buck converter that I mentioned in the beginning of the thread.

Its a 10 Ohm 100 Watts variable resistor. The load is an electromagnet. I have connected a 50 Watt halogen lamp in series. I suppose the fluctuation happens below 1 Ampere.

For now it works ok.

Thanks.

 

I can't understand how you are getting 2 different currents from a constant current converter.

(without changing the settings of the converter)