Solid State Relay (SSR) with Optocoupler and Triac

This solid state relay (SSR)  equivalent circuit is made of optocoupler and a triac. This SSR circuit is also designed with  LED protection from overvoltage and reverse polarity. The diode 1N4002 is the reverse polarity protector, as it will short the wrong polarity to null the voltage with the help of 150 Ohm series resistor.  The 2N4403 transistor will protect […]

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Light Level Droplets Detector

This is a circuit of Low-Light Level Drop Detector. This circuit utilize self-biasing configuration to detect small changes in light level. This circuit usually used in monitoring very low droplets rates. The collector of the transistor gives feedback that is used to stabilize the bias of the photodarlington. The effect on optical performance is reduced by a high base-source impedance […]

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Very Simple Light Meter

Very simple light meter can be constructed using LDR (light dependent resistor)  wired in series with a battery, variable resistor, and  ampere meter. Here is the schematic diagram of the circuit: The ampere meter is a 100 uA analog meter. Don’t expect too much about the linearity, absolutely can’t be compared to standard light intensity meter which measure luminosity in […]

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