Hi All
I have tried to create a simple circuit using a IRF540A mosfet. I have a PICAXE 08M2 in the circuit. The picaxe has a simple program that monitors the ADCVAL of pin 3. The pin is connected to a positive source via a home made touch switch i.e two screws that when you touch the screws the ADCVAL increases, Picaxe reads this increase and turns on or sets high pin 6. This is then attatched to the gate of a IRF540A mosfet. The source is connected to negative of the battery and the drain is connected to a buck/boost micro puck 2009sho which is connected to an LED which is connected to Positive.
All works well. The Picaxe works perfectly and so does the home made contact switch. The LED works and so does the MOSFET. However for some reason the LED will not burn as bright as it should it seams as though the mosfet is acting like a resisitor??? Its getting a little warm and if I remove the MOSFET by simply attaching the drain to negative the LED burns as bright as is expected.
I understand that the MOSFET is the problem here but please can someone explain why? and what should I look at in the TECH SPEC to overcome this,,,or do I need an alternative. My understanding of technical wording is very limited so please explain technical phrases. If someone can suggest an alternative Id be gratfull.
The system runs on 5V supply.
Thanks for you help.
Justin
I have tried to create a simple circuit using a IRF540A mosfet. I have a PICAXE 08M2 in the circuit. The picaxe has a simple program that monitors the ADCVAL of pin 3. The pin is connected to a positive source via a home made touch switch i.e two screws that when you touch the screws the ADCVAL increases, Picaxe reads this increase and turns on or sets high pin 6. This is then attatched to the gate of a IRF540A mosfet. The source is connected to negative of the battery and the drain is connected to a buck/boost micro puck 2009sho which is connected to an LED which is connected to Positive.
All works well. The Picaxe works perfectly and so does the home made contact switch. The LED works and so does the MOSFET. However for some reason the LED will not burn as bright as it should it seams as though the mosfet is acting like a resisitor??? Its getting a little warm and if I remove the MOSFET by simply attaching the drain to negative the LED burns as bright as is expected.
I understand that the MOSFET is the problem here but please can someone explain why? and what should I look at in the TECH SPEC to overcome this,,,or do I need an alternative. My understanding of technical wording is very limited so please explain technical phrases. If someone can suggest an alternative Id be gratfull.
The system runs on 5V supply.
Thanks for you help.
Justin
Last edited: