Fun with Electronics

I'm thinking to use pressure sensor for my RC plane so that I can tell how high it fly. Singapore regulation says I cannot fly higher than 60 meter without permit. Although my RC plane at yet to fly 😁, last time I try it fly like a rock, high speed nose dive 😂. 60 meters (200 ft) is actualy not that high, I leave in 25th floor and it is around 99 meters based on my Mi Watch 2 altitude meter. I bought the sensor from AliExpress for SGD $1.37. There are 2 choice, BME or BMP. Both look almos identitcal. The BME is more squarish as show on the picture below. BMP does not have humidity sensor but BMP is cheaper, about 1/3 the price of BME. Anyway I just need the pressure sensor to measure the approximate altitude. I use the BME280 library by Tyler Glenn. Why? No reason, it just happen to be on the top list when I search at library manager. I'm sure the other library will also work. Schematic from the seller site: The Arduino nano connection to the BMP280 is as below The experiment...

ADS1115 is 4 channel 16 bit Analog to digital converter. Actually I only need 1 channel to measure the battery voltage but unfortunately ADS1013/ADS1113/ADS1014/ADS1114 module not available at AliExpress and ADS1115 cost about SGD1.80 which is quite reasonable 😁. The reason I'm looking into analog to digital converter is because the remote control transmitter that I made here , out of analog input to measure battery voltage. I'm not sure if I have enough memory space for it though😕. I got the schematic below from internet, I posted here for reference. Take note the ADDR pin is pull to ground by 10K resistor, which mean by the default address is 0x48. ADDR = 0x48 if ADDR pin connected to GND ADDR = 0x49 if ADDR pin connected to VCC ADDR = 0x4A if ADDR pin connected to SDA ADDR = 0x4B if ADDR pin connected to SCL Nothing special on the Arduino Nano connection either. I used 10K potentiometer just for testing purpose. In real application it will be connected to Lithium Ion batte...

On my 6 Channel Remote Control project, I discovered it hang at random time within ~15 minutes. Accidentally I discovered that it will immediately hang when I touch the I2C line (SDA, SCK). Another observation is the OLED is glitching randomly. Initially I though it is separate issue but the solution for hang also solve the glitching. (1) At first I though maybe because of noisy power supply causing the microcontroller to hang. So I add 100uF capacitor on the 5V. It does help, still hang (2) Since it was immediately hang when I touch the SDA/SCK, maybe by touching I'm adding capacitive load, slowing down I2C signal and causing communication error to OLED. I add 4.7K pull-up resistor to increase rise time but it make it worst, the remote control hang immediately after displaying welcome message on OLED even without touching SDA/SCL 😱. Not a clue what going on, I hook up oscilloscope and see something interesting. There are 2 clocks frequency during communication, 99kHz on the left...

I replace the LCD to the smaller 1.3" OLED, that way I can reduce the size of the transmitter 😉. More compact compare to the previous attempt here . I also completed the menu system. Initially I was thinking to make it customizable, meaning you can assign any channel to throttle or elevator or rudder. However after half way of coding, I realize the code become very complex 😵 and the worst part is out of memory space which I do not know how to reduce 😬. Back to drawing board, this time I design it in opposite direction. I define which channel use for which purpose. However, I still want to have some kind of flexibility. Thus I introduce transmitter mode selection where you can select the target device you want to control, such as car, plane, delta wing, quadcopter, etc. Address trimming setting and channel reverse setting This is the idle screen look like, in picture below the remote was set to PLANE-A which is single servo aileron. As you can see it is telling you to connect CH...

I bought another motor, 1503 2750KV, it come with a propeller. The propeller size is about 12cm. The plan is to use this motor to convert glider plane into RC plane 😄 Unfortunately the shop does not have trust information with provided propeller and I do not have test setup to measure it. Size: 1503 Voltage: 3.7V - 8.4V (1 - 2S) ESC: 10A and above Kv value: 2750 Weight: 8 gram Shaft diameter 2 mm There are many different 1503 motor at Aliexpress, some are very cheap S$2. The one I bought is S$4.80. All of them look similar, picture below will help to differentiate it. The one I bought have 5mm shaft protrude out, which is good, I can use different propeller. The motor mounting have metal under the cable. Also there is metal grid at the front which is not shown on pictures below but shown on picture on top.

I bought this motor to try to build quadcopter, but currently 3 of the motor used for the Hovercraft Rev.2  project. Description: KV : 4300 Stator Dimension : Φ11mm x 4mm Dimensions : Φ14.3 mm x 17.6mm Idle Current :  0.5A Maximum Current : 6-12 A (based on table below, 2.5A max, not sure if it is true) Maximum Power 62.4 W Prop Shaft : Φ1.5mm x 5mm Interphase Resistance : 470mΩ Mounting Holes : 8.5mm x 8.5mm (M1.4) Weight(including wire) : 5.9g±0.2g Recommended battery : 1-2S Propeller size : 2-3 inches Motor data below copied from one of the AliExpress shop