# Do I need an encoder/decoder? Remote Control question...

Thread Starter

#### medic265

Joined Mar 13, 2009
9
Hello Everyone,

I need to use several different remote control units to control some props in a haunted trail we put on every year for charity. There are a ton of cheap China made 433mhz remote control systems on Ebay that will probably work just fine. I'm sure you guys have seen and used them. They come in 1,2,4,6,8,12,etc channels and usually cost less than $20. Here's a link to a 4 channel model for reference (LINK). The problem is I need to use several of them in the same location. I've bought a couple and I can't see that there is a way to make sure that RX'er "A" works with TX'er "A", "B" works with "B" and so on. I'm not sure what this action is called (encoding/decoding maybe) (or maybe "addressing"). Is there a simple circuit or IC that I can build and add on to these? I'm not an electronics engineer by any means but I can follow directions and build a circuit from a schematic if I've got one. Thanks for any help or direction you can give. Greg #### MrChips Joined Oct 2, 2009 21,312 Find remote controllers that use DIP switches to set the device codes. Then each controller can be set to a unique code. Thread Starter #### medic265 Joined Mar 13, 2009 9 Find remote controllers that use DIP switches to set the device codes. Then each controller can be set to a unique code. Thank you Sir for your quick reply. I've looked at about a thousand listings similar to what I used as an example. I didn't see a DIP switch in any of the listings. But thanks for the suggestion. Greg #### Bernard Joined Aug 7, 2008 5,555 On 7/3/14 there was a similar requrst here, 2 chips were mentioned which gives 8 channels, Tx is HT12E & Rx is HT12D., no not recall author. Thread Starter #### medic265 Joined Mar 13, 2009 9 On 7/3/14 there was a similar requrst here, 2 chips were mentioned which gives 8 channels, Tx is HT12E & Rx is HT12D., no not recall author. I've seen some schematics using those IC's but there's was no discussion of the "address" issue that I'm talking about. I saw them on the internet but did not see the exact thread your referring to. I did a search on this forum for the words "remote control". It brought back 500 hits. I went through many of the threads but it's very hard to read 500 individual threads. So if this is true then I don't need anything else. I've got a 315mhz and a 433mhz but those don't help me with testing this. Of all the RC's that I looked at I haven't seen one good set of instructions for those units. And they don't come with any documentation at all. I guess I need to order another unit to match one I have and see if the remotes will cross link to the other receiver. I have seen a listing that had one 6-channel transmitter and 6 individual 1-channel receivers. And on the flip side of that I have also seen a couple of listings for a 4-channel receiver that had two 4-button key fob transmitters. So there has to be a way to reverse program them also I think. That would be handy as I need at least two 6-channel units with two transmitters each. So what I really need at this point is probably a good, detailed set of instructions for the units. Thanks again for your help and links. Greg Last edited: #### MrChips Joined Oct 2, 2009 21,312 I suspect that the remote controllers are designed to not interfere with each other. You pair each receiver/transmitter by pressing the LEARN button on the relay board and then press any key on the transmitter. Thread Starter #### medic265 Joined Mar 13, 2009 9 Just for the record, here are remotes that use DIP switches: http://www.elsema.com/prod-pcr.htm Thank you for that. I'll call them and check prices tomorrow. And for the record my google-fu must be strong tonight...lol An hour or so ago I went out to the shop to take some pictures of the units to post here. I got curious while looking at them so I did a search for the IC numbers in the transmitter and found the following link (LINK). That gave me the "addressing" information I needed. There are about 6500 different address combinations which will be more than enough for what I need. I did verify that my transmitter board was the same. I should also mention that I had ordered an 8-channel system. But the transmitter has 12 buttons just like the one shown. The label covers up 4 of the holes and the silicon insert only has 8 positions. So my guess is they use this same transmitter for all units up to 12-channels and just cover up the unneeded holes. From the link above I went to the receiver board page on that site. The 12 channel receiver shown uses the same IC's that are in my 8-channel receiver. The receiver page says that the IC can store up to 10 different transmitter codes so that's how they are using multiple transmitters on one receiver. So if you've ever wondered about these cheap little rf remote controls I suggest you check out that link and do a little reading. I was able to answer all the questions I had from there. I looked up the 2 IC's used in the receiver. Together they were priced at around$1.50. I'm sure the transmitter and receiver could be built quite cheaply. But these things are less than \$20 on Ebay so I'm not sure it would be worth the trouble.

I hope that others will find some useful information in the links above. And I certainly appreciate everyone's generosity with help. So many times I see newbies get a reply of "use the search feature" but that was not the case here and I appreciate that.

Regards
Greg

#### MikeML

Joined Oct 2, 2009
5,444
...
The problem is I need to use several of them in the same location. I've bought a couple and I can't see that there is a way to make sure that RX'er "A" works with TX'er "A", "B" works with "B" and so on. I'm not sure what this action is called (encoding/decoding maybe) (or maybe "addressing").
Greg, I recently bought some of these. They are based on the PT2272 remote control chip set...

These have a fixed strap-able address both in the encoder and the decoder. Both the encoder chip and decoder chip have 8 address pins. Each pin can be jumped high, low or left open, giving 3^8=6561 unique codes. They are shipped with all eight pins floating...

The bottom line is, you can have multiple four-channel fobs each talking to its own receiver in the same building. You could have a collision if two fobs are activated at the same time, but if they transmit sequentially, then each receiver will respond only it's own transmitter.

These receivers have no relays; just four CMOS outputs that goes to 5V when the corresponding button is pushed. The output stays high for as long as the button is depressed.

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