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Why does my RC transmitter/receiver work after removing this magnet? Answered

The RC parts I've been tinkering with have a small electromagnetic coil. The radio frequency can be tuned by using a screwdriver to raise or lower the magnetic core.

What puzzles me is that the transmitter and receiver will still work if the magnetic core is removed from both parts. This seems like an important component, so why does it work without it? What's happening to the radio frequency?

Bonus question: What's the purpose of the capacitor on the receiver board?

For context, I'm working on an RC car project for kids and I'm trying to figure out how to diversify the radio frequencies so more kids can operate their cars at the same time.

Thanks for your help!


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1 year ago

The "core" is a piece of ferrite and it adjusts the inductivity.
The tuning of it gets important once distance and interference come in.
Being a simple AM transmitter system they have quite high tolerances - at short distance.
Do the tst and increase the distance until the remote fails.
Then start adjusting the core on either the transmitter or receiver side until you get maximum operating distance.
The Capacitor, if you mean the ones next to the red wire are mainly to provide a buffer when a button is pressed.
Instead of draining the battery most of the required energy is taken from what is stored in the capacitor.
Helps to get a longer battery life.
On systems with a power supply instead of a battery the capacitor also ensures that far less interference makes it from the power supply into the transmitting or receiving parts.