Electronics > Projects, Designs, and Technical Stuff
diy 300W LED supply?
ETITsynthesizer:
R1 C1 make a step down from 170v to 9v. I figured that a full wave rectifier would give me 120Hz. C1 is also the power supply smoothing cap. then there is a 5v zener for the 5v ref and analog comparator IC supply. the pot is the 0v to 5v reference. the output of the SMPS feeds back to the analog comparator. I have the LM311 collector output switching the 2N6213. I designed it to get 1.5mA into the base of the 2N6213. all the caps and resistors are rated for where they are. I'm not sure if the LM311 is ok because the datasheet has 16mA at 30v. I have 1.5mA at 170v.
my load is 3 100W LED's in series screwed to a common heat sink. still not sure if the LED's have some grounded chassis or what. in the planning stages now. I will test with a dummy load before I connect the LED's.
I think it would be safer to not earth this circuit since it has two mains wires and no transformer isolation. maybe I need a fuse or two?
Berni:
To me it looks like it at least won't explode, but it won't really be doing much in the way of regulation because that transistor will be permanently turned on by a small current into the opamp.
ggchab:
I am not an expert but isn't this circuit a bit dangerous for you (direct connection to the mains) and for the LED's (no current control) ?
ETITsynthesizer:
--- Quote from: Berni on November 18, 2019, 07:26:02 am ---To me it looks like it at least won't explode, but it won't really be doing much in the way of regulation because that transistor will be permanently turned on by a small current into the opamp.
--- End quote ---
thanks for your help. I think I fixed it now. let me know if there is anything else. obviously this is an unsafe product. I will probably just build it to test and then build the real one with the transformer later.
mouser cart is $16.98 USD for two transistors, a comparator and a zener. most of that is in the transistor for $14.23.
Berni:
That is better
You might still want to do some math on your resistor values to make sure you got enough power to turn on the power transistor. Might make sense to add a darlington pair there depending on how things work out. You might also want some direct negative feedback from the opamps output since these sort of inherently unstable pass stages love to oscillate.
Also its a bit confusing that you are trying to drive LEDs with a constant voltage output. Usually it makes more sense to drive LEDs using constant current. You would also want your main storage capacitor to be before the pass transistor for best output stability, unless the reason for putting it there is to get a better power factor.
If you don't know what you are doing its best not to mess with mains since when things go wrong they can go really wrong. The thing would most definitely require a fuse and a grounded case.
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