How to use pc817 and tip122 to control rectified mains LED array?
I have 3sets of leds that conduct at 250v so I wanted to use my 100v TIP122 NPN(with TVS diodes to protect it from over voltage) and PC817 opto-isolator to PWM the LEDs which are common cathode, is there a way?
Thank you all for all the superb suggestoins!
Discussions
2 years ago
Your PC817 opto-isolator is only able to handle 80V and TIP122 is only a 100V 5A Darlington NPN..
I never design a transistor switch without 150% Voltage safety.. LEDs may not turn on, but they do not start blocking at a magic value, especially a module..
If you know how to use a voltmeter put it in place of the Tip122 !
Included is a simple way to light anything from a uP..
Answer 2 years ago
I think your circuit would have a higher BOM, since the led conduct only within this 100v range, even 70v range worked ok, do you know any good 100v opto-isolator? The PWM would also be better with the transistor right?
Answer 2 years ago
I dont really need a multimeter check since I will have a tvs or zener diode to protect the transistor and optocoupler
2 years ago
LTV-358T seems to be a great optoisolator for this situation
2 years ago
the opto-isolator is only 35v that is the issue
Answer 2 years ago
It is rectified 220VAC, 310-320VDC
Answer 2 years ago
Iceng's scheme with a triac is a good one, and easy to make.
2 years ago
You don't have any suitable parts for the voltages you want to work with.
2 years ago
No clue without proper info ;)