Here are some of the most popular topics in test & measurement being discussed in our EDAboard.com sister site.
Measuring antenna radiation — I had a problem measuring and understanding the problem of quantifying radiation patterns. I am working on a dongle application. How do I measure and test my simulation value range and what I’ll need in terms of range for a dongle? Specically, what should the E and H field configuration be within the radiation pattern? And should the pattern be omni-, uni- or bi-directional? Read more.
Repairing a car audio amplifier – I want to repair a car amplifier board. Problem: I need to replace a component but I don’t know what it is! It seems to have the same color code as a resistor but it has the letter “S” in the end of a printed value on board (below the component). For example : Red-red-black is device color and “22S” is printed on board, or yellow-violet-brown is the color code and “471S” is printed on board. An auto-range ohm meter shows open circuit for all these devices!!! So what is this component and what is its job? How do I test whether it failed or not? Read more.
Measuring an ac voltage that varies – I tried measuring ac voltage using a potential transformer having a 6-V output and rectified before passing through a capacitor (1 μf 50 V) and voltage divider (390 k and 10 kΩ) then to an ADC pin. The voltage at ADC pin is stable but the voltage at the output varies. Sometimes it displays 240 V, 174 V, 200 V and so on but the voltage at the ADC pin remains 2.2 V. My question is should I increase the capacitor used to filter the rectified output from 1 μ to 100 μ? Read more.
DIY cheap instrument – I can’t afford a real instrument to perform precision voltage measurements, but I figure there must be a good way for me to create a device for my measurement range. I have acquired an Analog Discovery from Digilent and I need to calibrate it. There are voltage reference ICs such as TI’s REF20xx.The best of them has an initial accuracy of 0.05% and drift specs are good too…..If I have a voltage which I know is within 0.05% of 3 V, can I use this as a start for a setup to verify voltages around 1 V? Read more.
A Chinese CNC – I own a hobby CNC machine from China called the HY3040. You can find a lot of them on ebay, but non of them have controller boards inside resembling mine. In my case I have to change the board because the breakout is burned. I have two main problems: No documentation and knowledge insufficiency.
Generally, I know there are four control wires S,N,D,E between the breakout board and the controller board for each axis. From there each axis connects to the stepper motor with A+ A- B+ B- wires. Inside the control box I found strange wiring. The Chinese seller sent what he calls a “manul”, but it contains little information the breakout board ….A double-row 20P cable connects the main motor controller (which has 3 motors connected to for A+ A- B+ B-) to the breakout. On the burned board there is nothing written around the motor wire socket at the side of the board, but I guess that those wires are XE, XD, YE, YD, ZE, ZD. How could I be sure? Read more.
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