Any COB builders around? Best guides?

Budley Doright said:

Got a wiring diagram, those I can follow lol. I see three capacitors, a start, and two run's but that's the only things I know .

Click to expand...

yep. the formula written gives the reactance of the capacitor. a cap in AC turns into a resistor according to it's capacitance. i have a few caps on my lights so i can add more capacitance and remove some as i need more light. dont try using a three poled cap, ive seen them get hooked up wrong a few times. never used them myself. i think theyre in washing machines and some definitely in some magnetic ballasts.


this is a reaaaally basic constant voltage circuit. you can measure the voltage on the rectifier with or without a dumby load. but use a dumby load. and like i think i stated before, use a fuse when all's said and done. iv never blown a fuse from noise but better safe than sorry. especially in prototyping.

the caps i use are 200uF AC. i got some 125vac ones but they're dinky chinese and should have gotten the 240vac ones. i was being cheep.

i also have some 50uF 240vac cap that i put in parallel with the 200uF to add up to 250uF and give a slightly higher voltage.


i also.found that with smaller caps like 10uF ones you can reduce the voltage from 120 to 15ish.

the blue is like the schematic above, uses 4 LEDs in series. 30-36v each.

the red is the same general wiring but uses 6 LEDs since they run at about 20-24v each.

you could use any volt chip as long as you pick a safe number of chips in series

Budley Doright said:

Got a wiring diagram, those I can follow lol. I see three capacitors, a start, and two run's but that's the only things I know .

Click to expand...

and lastly you should determine what your voltage is and divide by the suggested current flow. use whole amperes and not milliamperes. you'l get a resistance of like 20-50 ohms depending on your specific chip. record this number. we now need to make a voltage divider where the reactance of the AC capacitor is the other resistor.

so we follow a voltage divider equation.

the LED is the bottom resistor^^ in there

you rearrange the formula to give you R1 (the top) because you know your input is 120v or whatever

and you know you want an LED to work on a specific resistance. resistance = voltage/current



to find the capacitance you must rearrange ^^ the thumbnail

threads got science!