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I'm trying to find out the frequency used by my RC car. In particular, what band it runs on (27MHz or 49 Mhz or something else).

It looks like this:

enter image description here

And the back view:

enter image description here

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  • \$\begingroup\$ What parts are on the reverse side of that board? \$\endgroup\$ – duskwuff Nov 4 '18 at 8:33
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    \$\begingroup\$ Had to upvote the most obvious.... \$\endgroup\$ – Solar Mike Nov 4 '18 at 8:57
  • \$\begingroup\$ Welcome to EE.SE! This appears to be a reverse engineering, modification, or repair question. Please be aware that such questions must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being discussed, so that you can ask specific, focused questions that can be answered concisely. Otherwise, the question is far too broad. More information can be found here: Is asking how to fix a faulty circuit on topic?. \$\endgroup\$ – Dave Tweed Nov 4 '18 at 11:55
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One can assume that the frequency is 2.4 GHz looking at the "2.4G" written on the board. A quick google on he "XL932R4" confirms this.

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  • \$\begingroup\$ I think I should have been clearer. I'm trying to figure out the band used by the RC car. It seems that most RC cars are either 27 Mhz or 49 Mhz. I want to find out which it is. \$\endgroup\$ – Benjamin Tan Wei Hao Nov 4 '18 at 9:00
  • \$\begingroup\$ You seem that assume that ir will be a frequency in the MHz range, but it obviously isn't. What about "2.4 GHz" don't you understand? \$\endgroup\$ – Wouter van Ooijen Nov 4 '18 at 9:25
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    \$\begingroup\$ Please update your post with a better explanation of what information you are looking for. If you're trying to reverse engineer this protocol I think you need to research the subject more. A good place to start might be here: hackaday.com/2016/06/28/… @BenjaminTanWeiHao \$\endgroup\$ – cutdact Nov 4 '18 at 9:33
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    \$\begingroup\$ 27 and 49 MHz used to be common frequencies for cheap, low quality RC toys with radio poorly performing radio remotes subject to interference. But 2.4 GHz system are now extremely inexpensive to make, and being digital packet schemes are able to reject corrupted data frames and use only the good ones. Because they can choose from a large code space it's typically possible to run any reasonable number of them in the same place, which means the manufacturer doesn't have to stock two versions and deal with returns when a parent of two children accidentally buys two on the same frequency. \$\endgroup\$ – Chris Stratton Nov 4 '18 at 14:10

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