New Lemon transmitter module, DIY & JR formats

[Martin]

I'm working on it now. I have two nRF24L01+ modules connected to a UNO (a Nano or similar would work too). One is connected to the usual pins: 9,10,11,12,13 the other is connected to 3,4,5,6,7. I'm programming it through the Serial (USB) interface, and I'm using the Serial Monitor on the PC to display the readings and enter control inputs.

Plan at the moment is to have a Scan command that will use just one of the modules to scan the band and display what it thinks are the two strongest frequencies present. Those become the default 'A' and 'B' frequencies when S is pressed again to stop scanning, or a different command is entered.

Then there will be A and B commands that allow you to enter the 'A' and 'B' frequencies manually, if you want to adjust them.

Finally a Transmit command that toggles between transmitting just on 'A', or just on 'B' or both, or neither.

I'll make a YouTube video demonstrating it once it's working. I have a Lemon transmitter module, but currently it's not connected up to anything. I guess I need to get that working too, to properly demonstrate the functions of my 'DSM2 jammer'

[Dave McDDD]

This sounds like a fantastic project!
If it ends up working as an effective DSM2 jammer, I'd like to build one of those too. Apparently the nRF24L01+ boards aren't that expensive since Amazon sells a pack of 10 for less than $13 US, and I've already got a Nano laying around.......although it's destined to be a Phil G encoder sometime in the future.

EDIT: After doing some further searching about the nRF24L01+, I see there are at least two different versions. One with a printed antenna, and another with an external antenna. Would the printed antenna version be powerful enough to work as a DSM2 jammer? Or are you using the nRF24L01+ with the external antenna?

[Martin]

At the moment, I'm just using the little printed antenna ones, but I have mounted them on the little carrier (adapter) boards you can get (also dirt cheap). The carrier boards are good because they have a 5V to 3.3V regulator. If you use them without the carrier boards then you can only power them from 3.3V (5V destroys the module) but the UNO and NANO 3.3 V supply is very weak, and you get problems with the module overwhelming the 3.3V supply when you try to transmit.

I think the little printed antenna boards will put out a strong enough jamming signal, if they're close to the receiver, and the 'real' DSM2 transmitter is some distance away. I have some stronger modules with built-in power amplifiers if necessary, but technically I could be breaking the law by transmitting continuous wave on fixed 2.4GHz frequencies at more than some specified power level for more than a few milliseconds.

[bluejets]

Cannot quite see your NRF units but there are also these which have the clip on external antenna socket.

https://www.banggood.com/GT-24-Digital ... ehouse=CN

[Mike_K]

Hi All

I hope nobody minds if I close this thread, LemonRx has brought out a revised firmware that addresses all the concerns with DSM2, so there is now no issue. Anybody in the UK can contact Stuart Mackay to get their modules upgraded (regardless if you bought them from Stuart or directly from LemonRx), those in other parts of the world need to contact LemonRx direct for arrangements. You can PM Stuart through this forum or email him smackayrc@aol.com

I'm a big fan of LemonRx products and have been using their receivers for years now in preference to Spektrum and OrangeRx as they perform as well as or better than the alternatives, they are competitively priced and best of all Frederick the owner actually listens and responds rapidly when things are brought to his attention, which Stuart Mackay did by email (I think Frederick is too busy to read forums every day).

All I can say about the Lemon DSMF modules is that I've now had 100s of flights using them, including with DSM2 receivers without a single problem and I would certainly recommend them, upgraded firmware or not. And before anybody asks, I have no financial involvement with LemonRx, just a satisfied user who has to buy them the same as everybody else!

Cheers Mike