EngineeringSlash- The electronic projects,electronic project,electronic schematic,electronic design » Light Sensitive Staircase Switch with Triac http://www.engineeringslash.com Engineering blog- electronic circuits , electronic projects,electronic schematic,electronic design,simple circuit and hobby circuits Tue, 09 Feb 2010 05:03:16 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Light Sensitive Staircase Switch with Triac http://www.engineeringslash.com/digital-ic/light-sensitive-staircase-switch-with-triac/light-sensitive-staircase-switch-with-triac.html http://www.engineeringslash.com/digital-ic/light-sensitive-staircase-switch-with-triac/light-sensitive-staircase-switch-with-triac.html#comments Thu, 21 Jan 2010 11:44:56 +0000 admin http://www.engineeringslash.com/?p=103 Operation of the third circuit is much similar except that it has photo sensitivity. The circuit is shown in Schematic

Light Sensitive Staircase Switch with Triac circuit 300x218

When there is no sufficient light/the reset pin is held low by R14 (4.7K resistor) and the circuit works as it is described in the earlier paragraph. But if there is sufficient light, resistance of LDR goes low and the transistor goes into conduction. Now the reset pin goes high and the circuit cannot work. R16 is the sensitivity adjustment. You may use a different color of LEDs at the emitter of Ql and Q4. You may construct the circuit on a single board and can use it for two different applications with a single IC of CD4013. You can use same application in two different latches or make both the same.

In general ICs do not like bad housekeeping, more so when handling mains voltages. Soldering is straightforward. A piece of Vero board is OK. But if you are mounting triacs on the same board, or separately, it is very important to have enough space between tracks such that high voltage arcs do not jump across. It is good idea to remove alternate tracks and mount triacs. BT136 triacs can easily drive 500 W of power. Suitable heat sink must be firmly fixed for each triac individually. Please respect CD4013, a CMOS IC.

Only two switches are shown as examples. You may add more number of switches for use at a number of different locations.

Please be careful that the entire circuit works off 230 V AC mains. If you wish to have isolation from the mains, use relays instead of triacs and use transformer power supply of 12V full wave. Light sense circuit consisting of Q5 and Q6 can be cleverly added to the relay circuit No.l

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