I needed a low power, very bright tail light for my Electric Bike (E-bike). I wanted something SIMPLE. I've looked up designs for LED drivers that had MANY parts. Dan's design only had 3 cheap parts. I found components that would work in my voltage range (Max ~60v).
I was previously using a standard 1157 (12v) automotive bulb (~20watt output) at ~15lm/watt = 300lm
Because it was a 12v bulb I needed a voltage regulator that was only ~50% Efficient, so previous power draw was 300lm/50watt or 6lm/Watt.
The new LED design has a ~10 fold increase in efficiency. ~50lm/watt
Step 1: High-Voltage (60v) LED Driver (CHEAP)
I’m using this as my low power tail light.
Input Voltage (50-60v) – 50v input min is based off the 46v LED unit. A different unit would have a lower input voltage, but would reduce efficiency of the regulator.
This regulator is rated at 300mA at 60v. Use of many 3.3 or 5v LED is also possible in series.
LED is rated at 125mA with a forward Bias Voltage of 46v - 55v
This Design Current ~100mA (Adjustable with different resistor value) Regulator is rated up to ~1.5A, so plenty of power capacity left in the design.
LED current in amps = 1.25 / R3
Capacitor Value - CAP ALUM 22UF 63V 20% RADIAL
Resistor Value - RES 12.4 OHM 1/4W 1% AXIAL
Regulator – IC REG LDO ADJ 1.5A TO220-3
All Part Numbers are from Digi-Key
For more details, please look up the part numbers listed below.
LED – (XMLHVW-Q2-0000-0000LT351CT-ND) - $5.72
LED Mounting Board – (BER272-ND) – $1.01
Regulator – (LM317HVT-ND) – $2.40
Capacitor – (P5190-ND) – $0.22
Resistor – (CMF12.4QFCT-ND) – $0.31
Heat sink – (SV-LED-113E-ND) - $2.22
Heat Sink Mounting Tape (1168-1715-ND) – $0.26