 # chinmoy1955

I am an electronics hobbyst, a DIY guy taking care of all the techinical stuff at home (and friends' homes!). I love to use the hammer, drill machine, screw driver (to screw anything that I can lay my hands on) etc. Profesionally, I own a manufacturing/production unit for professional quality PA audio equipment like audio mixers, digital echo units, amplifiers etc. My experience in electronics spans about 30 years.

• I wonder why people keep such meaningless, difficult to spell, and difficult to remember esoteric usernames like mnatanagara?

• You are wrong, the symbol is that of a P-Channel MOSFET. Below is the actual symbol of the Fairchild FQP50N06L MOSFET taken from their data sheet. Please be informed before commenting:

I had posted here about 8 months back about a serious flaw in the circuit diagram and related text. I am surprised to find that the original circuit is still being published without correcting the flaw. It seems the author does not bother to read the comments and the people following the post are also as much blind and misinformed as the author.I would like to once again point out the mistake. The circuit symbol of the MOSFET shown is that of a P-Channel Mosfet, and not N-Channel as written in the article. But funnily, the part number given is that of a N-Channel MOSFET. The proper symbol for the MOSFET mentioned in the article is given below:

• chinmoy1955 commented on Dipankar's instructable LED TUBE LIGHT (AC)3 years ago
• Congratulations on a simple but effective constant current circuit.The schematic symbol of the MOSFET shown in the circuit diagram is that of a P-Channel MOSFET, not N-Channel. Moreover, it is not a simple FET but a MOSFET.The power adapter voltage can be calculated as follows:V supply = 3.2 X n + 1VWhere 3.2 is the voltage drop across each led, n is the number of LED's in series.The 1V added in the end is to take care of any voltage drop that may occur in the power supply due to regulation errors. So a 6V supply can only feed one LED. A 12V supply can feed a maximum of 3 LED's. From the above rough formula we can say that 3 LED's in series will require:V = 3.2X3+1 = 10.6VSo a 12V supply will also work with 3 LED's, but to keep the power dissipation of the MOSFET at a minimum, it would ...

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Congratulations on a simple but effective constant current circuit.The schematic symbol of the MOSFET shown in the circuit diagram is that of a P-Channel MOSFET, not N-Channel. Moreover, it is not a simple FET but a MOSFET.The power adapter voltage can be calculated as follows:V supply = 3.2 X n + 1VWhere 3.2 is the voltage drop across each led, n is the number of LED's in series.The 1V added in the end is to take care of any voltage drop that may occur in the power supply due to regulation errors. So a 6V supply can only feed one LED. A 12V supply can feed a maximum of 3 LED's. From the above rough formula we can say that 3 LED's in series will require:V = 3.2X3+1 = 10.6VSo a 12V supply will also work with 3 LED's, but to keep the power dissipation of the MOSFET at a minimum, it would be advisable to keep the power supply voltage as close to the calculated value as possible, thus 11V would dissipate less heat than a 12V supply. So if you have a 24V supply available, you can safely connect 7 LED's in series.

• Congratulations on a simple but effective constant current circuit. It is very wrongly mentioned in the article that Q2 is a N-Channel FET. It is actually a P-Channel MOSFET, you may check it from the data sheets. Moreover, it is not a simple FET but a MOSFET.The power adapter voltage can be calculated as follows:V supply = 3.2 X n + 1VWhere 3.2 is the voltage drop across each led, n is the number of LED's in series.The 1V added in the end is to take care of any voltage drop that may occur in the power supply due to regulation errors. So a 6V supply can only feed one LED. A 12V supply can feed a maximum of 3 LED's. From the above rough formula we can say that 3 LED's in series will require:V = 3.2X3+1 = 10.6V So a 12V supply will also work with 3 LED's, but to keep the power dissipation...

see more »

Congratulations on a simple but effective constant current circuit. It is very wrongly mentioned in the article that Q2 is a N-Channel FET. It is actually a P-Channel MOSFET, you may check it from the data sheets. Moreover, it is not a simple FET but a MOSFET.The power adapter voltage can be calculated as follows:V supply = 3.2 X n + 1VWhere 3.2 is the voltage drop across each led, n is the number of LED's in series.The 1V added in the end is to take care of any voltage drop that may occur in the power supply due to regulation errors. So a 6V supply can only feed one LED. A 12V supply can feed a maximum of 3 LED's. From the above rough formula we can say that 3 LED's in series will require:V = 3.2X3+1 = 10.6V So a 12V supply will also work with 3 LED's, but to keep the power dissipation of the MOSFET at a minimum, it would be advisable to keep the power supply voltage as close to the calculated value as possible, thus 11V would dissipate less heat than a 12V supply. So if you have a 24V supply available, you can safely connect 7 LED's in series.