Once upon a time, RC transmitters were expensive units that cost hundreds of dollars even at the low end. Now, you can get them pretty cheaply, or, you can choose to build your own. [Phytion] did just that.
The design isn’t based around a modern microcontroller, nor does it rely on WiFi or Bluetooth connections. Instead, it’s a little more old school. It’s built using the HT12E parallel-to-serial encoder chip, and the HT12D decoder chip for the receiver. The controller uses a pair of HT12Es on the transmitter, and a pair of HT12Ds on the receiver. These accept inputs from a pair of analog joysticks and encode them as serial data. However, they essentially just act as digital joysticks in this design. The HT12Es feed into an STX882 module which transmits the data from the HT12Es over 433 MHz. Another STX882 module receives this signal, and passes it through HT12Ds for decoding.
At the receiving end, one joystick can turn four outputs on or off depending on whether it is pushed up, down, left or right. A channel select switch then allows it to do the same for four further outputs. The second joystick just mirrors the operation of the first. It’s just intended to make controlling something like an RC car easier by allowing one stick to be pushed forwards and backwards, and the other left and right.
You don’t see many designs like this anymore. Realistically, it’s possible to get far more functionality out of a design based on an ESP32 or similar wireless-capable chip. However, this one doesn’t require any complicated handshaking and powers up instantly, which is a nice bonus. Plus, it’s always interesting to see alternative designs tried out in the wild. Video after the break.
I once made a remote control system from ground up (not looking at any code nor using third party codes), using a pair of ATMEGA328 and 433Mhz transceivers. https://www.youtube.com/watch?v=Z_3vzpvni-w
TTS is beyond astonishing these days.
One thing to note with the ESP type options is they only work well over a very limited range where the Mhz simpler to decode RF stuff might well work over vast distance – obviously more complex than that, with antenna quality, orientation, transmission power, interference etc. So simply pointing out something like this might be the better solution for some users needs, once they do their research on the local restrictions.
Hmm… you can get pretty good range on an ESP32 using their transmit only stuff. It does have the benefit of frequency hopping too, so you probably won’t crash when someone opens their garage door.
Define ‘good’ range.. A failing that also falls on my post too. So to be clear I am not saying ESP32 type wifi solutions can’t be useful, or are so crippling short range they won’t even cover your postage stamp sized garden by any means. And the rules of your location on transmission power etc will really change the equations as well – but the MHz stuff has generally better range, and the simpler decode method will often still work on a very degraded signal (something quite noticeable if you have ever tried to use digital vs analog video transmissions – the digital signal might be crisper and clearer at the start, but then it suddenly turns to entirely nonsense garbage, where the swamped analog video just gets gradually noisier until eventually you have to be some kind of magician to make any sense of the snow…)
I think it’s illegal to use 433MHz like that (continuously over seconds/minutes)
But as a DIY project that one shouldn’t use inside populated areas it’s nice.
Pretty sure there’s “open” public Reserved Spectrum there, like there is around 50MHz. It’s “channelized”, so as long as you are in the channel and not generating spurious signals, you are OK. That’s one of the reasons you see a lot of “unlicensed” consumer products using 50MHz(49, really) and 433MHz, despite the latter being smack in the middle of an Amateur band(at least in the US)…
I’m talking about duty-cycle. All those consumer products have very low duty cycle. Meaning they transmit very short periods followed by long breaks when other devices can transmit their own temperature or what have you.
In most EU countries it’s allowed if bandwidth and/or power is low enough.
In the US, you can use it with a ham license. If it’s less than 1 watt and being used to control an RC model, then the remote doesn’t even need to transmit an ID.
I still enjoy the feel of an old-school Futaba with all the switches… I don’t know why.
Because they are better in most ways, but they are not DIY and that’s what “we” do here. If you hack it, that’s another thing ;-)
This has a feeling of Scam on top of a Scam, trying to imitate Alibaba/Aliexpress toy that pretends to be more than it is. No idea if intentional or not. Crimes committed here:
– AI voiceover.
– using analog stick despite being only capable of transmitting on/off signals. At first I actually thought HT12E had 4 analog inputs.
– using _two_ analog sticks while capable of only controlling 4 on/off signals.
– using two encoder chips with a switch instead of one encoder with switch wired to address pin.
– no idea whats the deal with all outputs being turned on by default when powering receiver.
I suddenly got flashbacks of cheap nineties remote controlled toys that came with legit looking remote but could only go straight forward or turn in reverse.
“could only go straight forward or turn in reverse.”
Oh, man. I’d forgotten about those. So disappointing.
And they sure predated the 90s. I’m pretty sure I was disappointed with them in the 70s.
I had one of them as a child, I remember being very upset when my dad stepped on it and broke the front wheels. He did fix it for me afterwards, and I was quite pleased with that.
The best one was the Tomy Char-G, it went forward and span on the spot. My brother and I never had enough batteries to power things, and the Char-G charged the car from the remote control, it gave us a few minutes of forward and spin fun.