Thank you sir. I tried it, but when IR sensor is blocked and motor starts running, it just run for 2-3 seconds and stops (even though IR is falling on receiver). Is there any solution for this?

You can use a Transistor as a Switch.

Encoding is required only if you want to control more than one devices or for transmitting any data. Here 38KHz is enough.

But in your circuit you have not used any kind of encoding. Then how the circuit is working?

For that probably you should use a microcontroller. With above circuit we can only do ON OFF controls.

Thanks for your prompt response. Much appreciated!

I recommend you to refer the datasheet of TSOP1838. It is written ,”The data format should not make a continuous signal transmission. There must be a Signal Gap Time(longer than 15ms) at least each 90ms.”. So I think this behavior is expected for TSOP1838.