Showing posts with label transformerless. Show all posts
Showing posts with label transformerless. Show all posts
Sunday, April 7, 2013
Surge Protected Cheap Transformerless Hi Watt LED Driver Circuit
This circuit is just a proof of concept just to show that the good old 555 timer can still be
used for a modern and quite demanding application. It is by no means an optimized circuit
that can be readily used for mass production. It appears relatively big by today's standard
because I used only through hole components. You may shrink it to 50 % of its original
size if you use modern SMD parts. You may also be able to increase the efficiency of this
circuit. Unfortunately I didnt't have time to do extensive measurements with all sorts of
inductors. There may be some room for optimizations.
Parts list
R1 2.2 kΩ / 0.1 W
R2 10 kΩ / 0.1 W
R3 100 kΩ / 0.1 W
R4 470 Ω / 0.1 W
R5 1 kΩ / 0.1 W
R6 2 Ω / 0.25W
C1 220 pF NPO ceramic disc capacitor
C2 10 µF / 16 V electrolytic
C3, C4 470 µF / 6.3 V, low ESR
L1 custom made transformer, see text
L2 47 µH / 2 A (TDK SLF 12575 / Fastron PIS4728 series)
D1 1N4148
D2 SB240 (SB360, MBRS240, MBRD650)
D3 BZX55C 4V7, 4.7 V Zener Diode
D4 1 W High Power LED
T1 BC 337-40 (2N2222A)
T2 BC547B (2N3904)
T3 2SK2869 (IRLR2905, IRLZ 34N)
IC1 ICM7555 (TLC555, HA17555)
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