LED solutions

Boost Regulator :bsdetector:




:bsdetector: Bi-Colour Latch



PWM analog clock :bsdetector:

Use Pot R~>=3Rf= (1k to 1M) to alter average DC input bias from Vcc to Gnd to change duty cycle with fixed Rf feedback. This is a fixed RC clock as shown with Schmitt Trigger gate or inverter without bias is near 50% square.: Adjust R values to give desired taper and 0~100% with f>1kHz for flicker free.

Click to expand...

:bsdetector: DIY Garden Fence LED Light shades

DIY outdoor luminaires using Cedar fence material, Alum.Clad board 4x1W with 14V routed under fence rail from central supply using AWG 18 speaker wire.

Click to expand...

:bsdetector: Blue Pool LEDs coated in clear epoxy





All diodes have a threshold voltage, Vth which is basically the voltage at very dim illumination, like a silicon diode is 0.6V and may be selected at say 1% of the rated current to measure estimate the dynamic resistance , Rd which we can approximate as a fixed Effective Series Resistance, ESR at rated current.

I usually extrapolate the curve to the zero axis (Vth) and Vf at rated current to measure ESR.

The following is an LG part for UV. The shorter wavelength chemistry has a higher Vth than Blue.

The Vf is always at rated current (not max) which is exponential but a linear regression to extrapolate Vf is useful. where Vf ~ Vth + I*ESR


I computed above Rd vs If from small differential V/I.

The Vf on a high power LED is lower because of the lower ESR. This ESR*Pd product is usually constant and useful to remember. ESR*Pd=1watt-ohm . Thus 0.5Ohm for a 2W LED.