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LED solutions

Boost Regulator :bsdetector:
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:bsdetector: Bi-Colour Latch
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PWM analog clock :bsdetector:
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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.

:bsdetector: DIY Garden Fence LED Light shades
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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.

:bsdetector: Blue Pool LEDs coated in clear epoxy
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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
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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.

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D.A.(Tony)Stewart
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