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Infrared Remote Control Safe Lock Circuit

Infrared Remote Control Safe Lock Circuit

A simple, cheap yet highly effective infrared remote control safe lock circuit can be studied in the following post.

infrared safe lock circuit

Using IC LM567

The LM567 IC is one of my favorites simply because it's too versatile, and becomes applicable in most of the crucial circuit concepts through hassle free configurations.

One such crucial yet simple IR remote control receiver application can be seen in the above diagram, which activates only through a unique predetermined frequency as set by R1/C1 in the circuit.

The above concept can be used in automotive security applications for locking the safe/vault through a uniquely set frequency code.

In the shown circuit R1/C1 determines the latching frequency of the unit, which may be calculated using the following formula:

f = 1/R1C1, which constitutes to be 100kHz for the shown values of R1, C1.

Pin3 which is the receptor pinout of the IC is configured with a IR diode for receiving an incoming tone locked frequency set at the matching 100kHz frequency.

How it Works

When such a matching frequency is detected at pin3 of the IC, pin8 responds and becomes low momentarily activating the transistor latch.

The transistor and relay latch together to acknowledge the response and open the safe lock for the user.



Any other frequency which may not coincide with the set R1/C1 value is simply rejected by the IC keeping the vault secured and locked, thus the system becomes extremely foolproof and safe from potential bike thieves.

pin1 output from the IC can be configured with an audio amplifier and buzzer in case an audio signal is felt essential during the remote control activation.

However this may require the transmitter to be equipped with a modulated audio signal over the carrier base frequency.

A very simple complementing IR remote handset circuit may be seen below:

It's a simple two transistor R/C based oscillator, whose frequency is determined by the shown R and C values and coincidentally here too the formula is identical to its Rx counterpart, that is:

f = 1/RC

Thus the Tx circuit frequency becomes much easier to calculate and match with the LM567 receiver circuit discussed in the previous section.

For activating the Rx circuit, the above Tx circuit IR diode emission simply needs to be focused on the IR receiver diode of the Rx unit. This instantly unlocks the Rx circuit for the intended results.

The  infrared remote control security lock circuit can be used for locking a multitude of other security devices which require a foolproof uniquely coded locking operations.

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About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!






15 thoughts on “Infrared Remote Control Safe Lock Circuit”

  1. Hi. Thanks for sharing this up. I need to know which are the capacitors values. The one that comes from pin 2 and the other connected to the pin 6. Thanks!

  2. hi friend s I am learner. I want material like pcb, ldr, ic s etc. where I get all the stuff to do.
    please tell me on watsapp : 9494989482.

    • Shekhar, there are many online stores such as digikey, mouser, vegakit, onsemi from where you can get the required parts through courier and COD payment

  3. Hi Swagatam, great to see your circuits, they are very impressive. I am not sure if this is the right place to request this but I am looking for a secure RF remote which cannot be copied (easily). I could not find anything on the internet except some suggestions to use Keyloq – but how , couldn't figure that out. I am an electronics hobbyist so if you give some ideas I will be able to carry it forward.

    • Hi, sorry but I am past that stage. I have already bought these and am able to control them using Arduino. I am also working on making it available via the internet. All that is cake, what I am looking for is to make this secure. At present as I have hacked this remote and simulated the same signals, any other person can also do that and would be able to control my house (provided he is near enough). I want to make this communication secure so that I can avoid that. Even if I have to build the entire thing for that – I am game for that. The only thing is that I have not been able to get any ideas of how to make it secure. The only thing I got was that car remotes also use the Keyloq algo where each code generated is unique and hence difficult to predict for hackers. Couldn't get enough info on the algo and the way to implement it.

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