Which small RC receiver to choose?

Question

Do it yourself

It is necessary to remotely and briefly turn on a small load (LED / micromotor). Range to loading no more than 5 meters (in the apartment). There will never be a concrete barrier between the receiver and transmitter, but there may be a bed/door. Which receiver and transmitter is better to choose? Preferably up to $ 5 and working from + -3 volts (tablet battery).
PS I want to make a micro-bugger for a cat.
PPS Is it possible to make a micro receiver from the simplest components? Because I live in a small town, then without delivery you can only buy transistors / resistors / etc. There is no way to buy ready-made modules.

Answer 1

There is a book on this subject "Remote control of 500 circuit models", there are many circuits of simple regenerative receivers and transmitters at 27 MHz. The component base is simple, but there will be problems with the setup without any SDR receiver, for example, or an oscilloscope. Those. yes, it is possible to make from simple components - no more complicated than transistors, and self-twisted coils in the form of a spring for 10 turns without a core, you can. But not easy.
And there are simple Chinese modules sold for about a dollar per pair - a 433 MHz receiver and transmitter - https://habr.com/post/224459/
Range hundreds of meters with antenna. But there are features, you need to understand how it works. Either you need to encode the signal into a digital code, then you need a controller, or transmit some low frequency of a few kilohertz, and encode the signal with it. And on the receiver to filter it somehow. It is easy to make a generator for several kilohertz at 555. You need to think about how to make a filter on the receiver.

Answer 2

Start by googling about nrf24l01 so that you don’t worry about all sorts of radio paths and filters