In this post I have explained a simple IR based remote controlled night lamp timer circuit. The idea was requested by Mr. Raj Kumar Mukherji.
Technical Specifications
Please provide the component values and the modified circuit if:
a. the circuit is made to work from 4.5 volts or 5 volts
b. the relay is replaced with a 5mm LED
c. the circuit is triggered by TSOP1738
d the delay time is set for 2 mins max
This is for an old person in my locality. He wants a low cost portable light which he would turn on
remotely for a brief period at night and the light would get turned off automatically. He has to get up at night to drink water etc and he does not want a night lamp to be on the whole night or to operate one from the mains power. The best idea that came in my mind is to use the transistorized timer circuit in combination with a TSOP1738 and using 2 or 3 AA cells.
Thanks and regards,
Raj Kumar Mukherji
The Design
The proposed remote night lamp timer circuit can be visualized in the above diagram and understood with the following points:
The IR sensor TSOP1738 responds to an incoming IR signal from a suitable IR handset such as a TV remote or similar, and produces a logic low at its pin labelled as "out". The directed Tx signal could be momentary, probably for a fraction of a second for initiating the triggering response in the circuit.
The above action instantly charges the 100uF and also switches ON the BC557. This correspondingly turns on the BC547 and the LED.
The stored charge sustains the switched ON position for a certain time period determined via the selected values of the 100uF capacitor and the 1M resistor. These may be altered, experimented for acquiring any desired time delay for the LED illumination period.
The 100uF slowly starts discharging via the 1M resistor and the base/emitter of the BC557 until it becomes too low for the transistors to hold the conduction, the LED consequently is also switched OFF as soon the RC determined time is elapsed.
The 1K and the 1N4148 diode ensures a complete discharge of the timing capacitor 100uF each time the LED is switched OFF, so that the new cycle is able to begin with a correctly discharged capacitor, for executing consistent time delays, with minimum errors.
The above design can be upgraded as shown below for getting improved response:
Comments
Hi Swagatam,
I just love your circuits and have just finished drawing (in ExpressPCB) and etched some of them. Now I am looking forward to build them.
Could you provide me with a schematic for a timer circuit with presets and 7-segments?
I need a timer circuit where I can adjust the time from 0 to 999 seconds.
When adjusting the time preset the 7-segment shall show the preset time.
When time is running the 7-segments shall show the remaining time. When the time period has elapsed a relay should be activated.
Also needed a reset button to start all over.
Thank you,
Henrik
Hi Henrik,
0-999 seconds timer circuit with preset display is possible but showing the remaining time looks difficult,….. if i happen to crack it I'll post it in my blog…
Just a 10 ohm 1/4 watt resistor will work in series with 3v button cell. Use a push button to blink the ir.you are done.
I guess its simply a IR LED with Resister in series as per battery ?
SIr plz add one very simple circuit for IR Transmitter too which can operate on button cell. Then we can use it for many useful applications.
Ram you can refer to this article for the Tx circuit:
homemadecircuitsandschematics.blogspot.in/2013/03/simple-reliable-infrared-ir-remote.htmlmotion detector on online
oh Thanx bro.
What could be its remote swagatam ??
you can use any TV remote handset…
any suggestion for connection.
simply replace BC547 with TIP122
want this ckt to drive about 500mA at 3.3 volts, biasing with 4 v battery. My point of view is to add a tip122 as buffer for higher current application.. is it right??
yes that's correct!
hi swagatam,
i got a problem with this circuit, the circuit turns on automatically when its powered and stays on… i powered it with a 4v 500mah lead acid battery.. what could be the problem ?
That's great Bibin, thanks for the update.
Hi swagatam,
i replaced the tsop sensor with a new one.. now its working properly..
thankyou swagatam….
Hi Bibin,
remove the TSOP sensor and check.
If it still switches ON then definitely the problem could be somewhere in your design because without a ground signal to 1M the circuit can never switch ON.
If it's not the case then the problem could be with the sensor configuration, it may be leaking some ground to the 1M…which can be rectified either by adding a zener diode in series with its OUT pin or reduce its supply voltage for the same
or through some other alternative method which will eliminate a ground to 1M until the sensor is actually activated.
I have confusion in pin 2 and 5 , both are connected together then need to connect with resister ?
It's perfect…no resistor is required there.
Sir I want to add below circuit with this one but I have some confusion to connecting with IC pin. Can you check and conform . I bought all parts and dont want to bear burn of any part.
https://www.homemade-circuits.com/2011/12/how-to-build-simple-hi-efficiency-led.html
s1.postimg.org/n8dgq7fen/IC_4049.jpg
Ram, the diagram is clearly shown in this post:
https://www.homemade-circuits.com/2011/12/how-to-build-simple-hi-efficiency-led.html
please do it exactly according to this diagram and nothing will burn.
I want you to be realistic sir, can u refer me to an inverter circuit on your blog that can power a laptop and a 15watt cfl bulb at the same time I want a cost effective one sir. I know I can search for it myself but I want you to choose for me the load won't be too much as u can see
Cool
thanks!