The article relates a simple automatic infrared controlled staircase lamp circuit which switches ON only during the presence of a passer-by and switches OFF automatically after a predetermined delay once the occupant vacates the corridor . The idea was requested by Mr. Sriram.
The Request
The Request
Hai, Recently while i was searching for automatic motor circuit i got ur blog. U r doing great work. Now I am following ur blog. I am planning to fit a automatic staircase light in my house staircase. But i don't have enough knowledge to make a own circuit. I am not able to find a circuit according to my need i the internet. so i need ur help to design a circuit according to my specifications. Here the specifications :---
The circuit can work at 5v DC. A single circuit should contain 2 sensors. One sensor will be fixed at the first staircase, another one at the last staircase. The circuit should contain a relay to get output of 220v Ac. So that i can connect a CFL bulb in that circuit. If i cross any one of the sensor means the bulb should glow for 2 mins and it should switch off. And another thing is , suppose I crossed any one of the sensor, the bulb is started glowing for 2 mins. with in that 2 mins if I cross the another sensor means the time should reset for 2 mins and the bulb should glow for 2 mins more and it should switch off. The bulb should not flicker while the time is reset. Then a override switch switch should be there to switch on the bulb manually ( like a SPDT switch, up for sensor, center off, down means manual switch on the bulb). I hope u can help me.
The Design
The project is primarily intended to save unnecessary wastage of electricity by using a smart automatic sensor equipped lighting system as explained below:
As shown in the figure below, the proposed circuit idea of an automatic Infrared staircase light is fundamentally made up of two accurate proximity sensor stages coupled with each other for executing the above actions.
Each proximity sensor includes the IC LM567 frequency decoder chips which are rigged with a particular frequency set by the corresponding R3/C2 networks.
Each of the ICs become locked at these set frequencies which also become the transmitting frequencies for the respective ICs.
The above set frequencies drive the relevant Infrared photo diodes which transmit the coded IR waves for detecting an obstacle or human movement across the preferred zone.
On detection of an "obstacle" the IR waves are reflected back from the object and received by another photodiode positioned optimally for the procedures.
Since the received IR waves are set with the correct specified frequency of the IC, the received signals from D2 is readily accepted by the IC which in turn allows its pin8 to go low with the response.
The low response from pin8 of either of the LM567 ICs is fed to the trigger pin2 of a IC 555 monostable multivibrator (MMV) circuit.
The MMV responds to the trigger and activates its output to a high forcing the connected relay to switch ON itself, and the connected load across its contacts.
R9/C5 may be appropriately selected for obtaining the required amount of delay for the relay ON state and the lights.
T3 makes sure that the MMV timing initiates only after the human presence is eliminated, which ensures that the lights never goes off as long as the premise may be in an occupied condition.
The two sensor modules across the left of the corresponding LM567 ICs may be stationed across the ends of the staircase, as proposed, for implementing the desired procedures.