The MOSFET gets too hot and the voltage drops when I connect a load to my PWM speed controller

Thread Starter

Jerome De Guzman 1

Joined Oct 13, 2017
4
I recently made this PWM controller form Make Magazine and I noticed that the Mosfet gets too hot and whenever I connected a load (motor with propeller) the voltage output drops from 5V to around 1.8V.

Due to parts availability in my area I did not use the exact parts indicated on their site hence I used parts that are somewhat close in value.
Instead of using:
~ A100K potentiometer I used a B100K
~ 100μF axial-lead electrolytic capacitor, 35V 20% I used a 100μF radial electrolytic capacitor
~ 10K resistor, 1/8W I used a 10K resistor, 1/4W

Whenever I am using it on LED's it works fine however I want to use it as a fan controller so everytime I attach a dc motor (like the ones used on tamiya) which I think was rated at around 3-5V with a propeller attached to it, the Mosfet gets too hot and the speed of the motor was too slow. The input voltage is 5V and the output voltage is the same at full rotation of the potentiometer however when I connect the motor with the propeller the voltage drops to around 2V. When I remove the propeller on the motor it works fine.

Please help me I want to drive the motor easily using this setup running at 5V since I want it to be powered using a powerbank.

P.S. The trigger and Output connection on the schematic is interchanged I noticed it and fixed it on my connection.
 

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bertus

Joined Apr 5, 2008
20,085
Hello,

The 5 volts powersupply is close the the lower limit of 4.5 Volts for the NE555.
That the mosfet is getting hot, is because the gate voltage is to low to get it fully conducting.
Better use a IRL510 in stead of the IRF510, the logic gate version.

Bertus
 

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Thread Starter

Jerome De Guzman 1

Joined Oct 13, 2017
4
Hello,

The 5 volts powersupply is close the the lower limit of 4.5 Volts for the NE555.
That the mosfet is getting hot, is because the gate voltage is to low to get it fully conducting.
Better use a IRL510 in stead of the IRF510, the logic gate version.

Bertus
Thanks, I will try to replace it with IRL510 :D
 

Thread Starter

Jerome De Guzman 1

Joined Oct 13, 2017
4
Hello,

The 5 volts powersupply is close the the lower limit of 4.5 Volts for the NE555.
That the mosfet is getting hot, is because the gate voltage is to low to get it fully conducting.
Better use a IRL510 in stead of the IRF510, the logic gate version.

Bertus
Regarding the NE555 should I use a boost converter before plugging it into the PWM controller in order to achieve a higher gate voltage?? I really need it to be powered by a powerbank since i'll be using it for camping haha
 
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