Here I've attached the schematic and yhre board of my buck converter, which is using MC34063 Regulator IC to supply a 1W LED. I successfully managed to get the required voltage 3.3v but it is not sourcing the required current 350mA giving only 40mA, I am not able to figure this.
Calculation for this output from 12V says:
Ct=216 pF
Ipk=700 mA
Rsc=0.429 Ohm
Lmin=60 uH
Co=15 uF
R1=11k R2=18k (3.3V)
My configuration:
Ct = 220pf
Rsc = 0.5R (Two 1R 1/4W res in parallel)
L = I wound my self on a 6X8 drum core inductor got from junk.
Diode 1n5819
Co = 10uF
R1 and R2 through preset
What I tried
changing Rsc with 0.2Ohm 2W but current not increased
changing voltage divider with smaller value
changing out filter capcitor with bigger value
changing core size to 8X10 with thicker wire
changing Ct 133 (100 +33) for 100kHz and 220 for 60
Changing Inductor (size and number of turns both , not sure about the inductor material, wounded and measured the inductance from an arduino program)
What I am not abble to understand which component affects the output current most (Since Rsc doing nothing) Rsc or the Inductor or voltage dividers value?
Questions:
1. How to increase the current 350mA to the LED or the Output current 40mA at 3.3V is what that LED need?
2. Any DIY method to make milliohm resistors?
3. How to determine the Inductor saturation (I am dumb in Inductors)?