neonzeon
  • Member for 7 years
  • Last seen more than a month ago
ESP8266 eLUA (NodeMCU) vs MicroPython
Accepted answer
23 votes

Here's a slightly different approach in stead of a Lua vs. Python shootout: Six of the most popular ESP8266 "runtimes": AT Command SET. Popular when the 8266 is paired with another MCU. Communicates ...

View answer
32 kHz crystal not operating as expected
Accepted answer
13 votes

The MCU maker is likely at fault. There is absolutely no excuse for not designing a modern MCU RTC oscillator to reliably function with any typical commercially available 32kHz crystal. Unfortunately,...

View answer
What is the minimum distance that BLE 4.0 capable device be programmed for..?
Accepted answer
10 votes

The goal of this rather long analysis is to ensure you look like the sharpest RF dude your company has ever hired :) The free space path loss range of a an RF system can be calculated. For a typical ...

View answer
STM32 HAL UART transmission
6 votes

You receive ~67 characters, which at 10 bits/character, is 670 bits. Given that your timeout (parameter 4) is set to 10ms or 0.01 s, the average bit rate seems to be around 67000 bit/s. My guess is ...

View answer
How to measure antenna S21?
5 votes

In a two-port network, S21 is the complex number that describes the linear power gain of the network. (it's kinda backward - S2 is output, S1 is input). It's a complex number because it is used to ...

View answer
Do they make variable isolation transformers?
5 votes

You must be thinking about an isolated variac

View answer
What free IDE does everyone use for the stm32?
5 votes

Definitely mbed.org Mbed is a free ARM-supported online IDE with open libraries, revision control & online community. The IDE runs in your web browser, so you can work from any PC and collaborate ...

View answer
12V Sealed lead acid battery level sensing
Accepted answer
4 votes

The "dead" or "end" voltage you are looking for is 11V (1.83V/cell) at room temperature. Below are typical discharge curves for a 20Ah 12V battery - note how the 1A curve ends just below 11V. The ...

View answer
How is this CD4013 application supposed to work?
4 votes

Here's a simulation of how it should work. Explanation below. Note that IC204, the TC4013BP master clock divider, is known to fail on the Roland RS-09. Here's a recording during which it failed. If ...

View answer
Conversion from dBm to Volt/ meter
Accepted answer
4 votes

Please fasten your seatbelts - our flight today will fly over a bit of the math to get from power (dBm) to field strength (V/m). The most pragmatic way to think about the "strength" of any RF signal ...

View answer
What is a 50-ohm antenna? How would you make one?
4 votes

It's also useful to understand why a 50-ohm antenna is so important. Let's say you have a source with an output impedance (resistance) of 50 ohms, like the ideal battery/resistor combination in the ...

View answer
High frequency transformer
4 votes

The most basic model of a transformer primary is that of an inductor connected across the two primary terminals. The impedance of the primary inductor is given by \$Impedance = 2\cdot \pi \cdot ...

View answer
How a Cmos not gate works
4 votes

Sometimes it helps to think of the FETs as ideal switches. In this picture the lower FET is conducting.

View answer
Simulate capacitor discharge in Qucs
Accepted answer
3 votes

One of the really cool lumped components in Qucs is a time controlled switch. You can specify the initial value as open or closed (see below), as well as a list of times when the switch should change ...

View answer
Clap Lamp debounce
Accepted answer
3 votes

No need for interrupts here. First remove the digitalWrite from your void loop(){}. Now, put this in your void loop(){}: if (digitalRead(trigger)==1) { state = !state; digitalWrite(...

View answer
Why doesn't the LM7805 circuit short circuit?
3 votes

Your thinking is actually 100% correct! The "electricity" (current) does "fill up" the 0.33uF capacitor before flowing to the 7505 regulator. However, the capacitor "fills up" in a fraction ...

View answer
LF-RFID demodulation
Accepted answer
3 votes

Your root problem is likely "First, I tried to apply the sampling and filtering to obtain the modulating signal." Your first step to obtain the modulating signal should be envelope detection. You ...

View answer
What happens if you add a voltage source to the output of an op-amp?
3 votes

Since an op amp is just a voltage controlled voltage source, I can translate your question into a simpler one: What happens in the circuit below?

View answer
What do the numbers mean on a three-position switch?
3 votes

The most likely conclusion is: The dotted line indicates that internally the two switches are mechanically linked. meaning that they switch over at roughly the same position and instant. Each switch ...

View answer
125kHz RFID System Design/Troubleshooting
2 votes

If you have an LC tank circuit and want to reduce the inductance at resonance: The inductor you have has inductance of L = 2.8mH: At 125kHz the inductive reactance is \$\mathsf{2 \pi \, f \, L}\$ = ...

View answer
qucs capacitor simulation
Accepted answer
2 votes

It's because the "probe" or voltmeter PR2 has (by design) an extremely high input resistance. Even the tiniest current (in fact no current at all) flowing through the capacitor will "move the needle" ...

View answer
Powering up Arduino + GSM with LiPo rider with a LiPo battery
2 votes

The key issue is that your GSM shield has its own on-board regulator (the huge 5-pin IC in the top right-hand corner of your photo) and requires VIN > 5V to provide a properly regulated 4.1V to the ...

View answer
How can I be sure that a multi-bit-per-symbol encoding schema exists?
2 votes

The other answers probably answered your title request. But as a student and young engineer I struggled with symbol-vs-bit concepts. If I use more than 2 symbols to represent the binary data, and ...

View answer
How to validate 32k crystal for BLE?
2 votes

From the nRF52832 data sheet: The easiest is to pulse or toggle a GPIO pin on every TICK interrupt and measure the frequency on your oscilloscope, or even better, compare with a known accurate ...

View answer
How can I implement this Truth Table with MUX4 only?
2 votes

As you will see below, José was extremely close. Never give up! Assuming X1:X0 (IN2:IN1) is the right hand multiplexer in José's diagram. For RH mux input D0 selected: X3 X2 X1 X0 Z(D0) 0 ...

View answer
Skew planar wheel antenna - is it circularly polarised or not?
Accepted answer
2 votes

Figure 10 of this excellent explanation boils down to this: If you ignore all the currents that cancel each other out due to symmetry, you can physically guide (via the copper) three currents Ez of ...

View answer
Signal processing to demodulate LF RFID
Accepted answer
2 votes

Fundamentally your approach is sound, but there are a few caveats. First, your "downconversion" is really AM detection. Since you are sampling every second cycle of the carrier, and hopefully ...

View answer
GPS Patch Antenna Feed Pin PCB Layout
2 votes

As you can see in the picture of the bottom of the patch antenna, the manufacturer also has an opening in the ground plane of the antenna where the feed exits. You will be fine if you match the ...

View answer
How is the bias current reference value determined for CMOS circuit design?
2 votes

The simple answer is NOISE tradeoff. Noise issues are typically forgotten in digital circuit design, (because the signal-to-noise ratio is sufficiently high) but when they matter (e.g. high gain ...

View answer
Measuring crystal drive strength without a current probe
1 votes

This online crystal oscillator simulation may help you estimate the power dissipated in the series (motional) resistance of your crystal by using the (AC) output voltage of the MCU. The model is from ...

View answer