June 1, 2024

Under Construction

The last year or so I've really gotten into the RC Helicopter hobby. I've acquired several models at the time of writing this and I'm really enjoying every aspect of it. I've even created some parts for several models. I'm running a Goosky RS4 currently and have a Spektrum Satellite on board, but I don't have the proper equipment to set the satellite into bind mode. This project aims to solve that. 

Introduction

Circuit Design

I originally kicked around a couple different ideas for this circuit. At first I was just going to use a simple timing circuit to essentially wait long enough for the nine pulses to occur and I even developed the circuit, which was operational, but the more I thought about it the less I liked it. It felt like it would be too prone to errors and I did not want to risk pushing the wrong number of pulses onto the satellite and binding in the wrong mode. I decided instead to count the number of pulses and stop the clock from ticking once it hit nine. 

To do this I wanted to use a JK flip-flop, but I was finding it a bit too complicated to recreate with discrete components. That's not to say it can't be done, I just didn't want this project to get away from me too much. After-all, this is supposed to be an easy step back into electronics after a pretty long break. Scouring the internet for a simpler solution I came across a much easier way to create a 4 bit counter here. Props to the original creator, it is a much simpler way to flip-flop on a clock. Reducing the component count is going to be a big deal here as I would like this to be as small or smaller than a credit card. 

After developing the 4 bit counter all that would be required is to simply look for the number 9 to come up. This is a pretty simple task with the use of some logic gates. The number 9 in binary is 1001 and I decided to flip the 0's with a couple inverters so I could run all 1's into a 4 input AND gate. From there I would just need to latch it once it's detected and pull the clock pulse high for the duration of binding. I inverted the signal using a NAND gate instead to trigger the latch, then the latch output is fed into an OR gate so once it goes high, the output of the OR gate will remain high. This is a pretty simple setup and I don't have any reason to believe that it won't work, but I will be doing more testing after putting together the first prototype. 

Below you can watch a video of the circuit simulation designed using Paul Falstad's circuit simulator. It has a few glitches and for some reason starts at a binary count of 7 (I had the LED's oriented backwards during this test so count runs from left to right here), but after the first glitch it starts up properly. Later in the video you will also see the latch reset, but that's another glitch that causes the voltage to suddenly disappear, which triggers a reset of the latch. This should not happen in real life, but I will be testing for it. 

PCB Design

Under Construction - Check Back Later!

Additional Resources

-Spektrum Remote Receiver Interfacing