Search
A couple of problems stick out; one glaring and one a little subtler. Read this in the data sheet: - You have the enable pin connected to your 25 volt output. I'm not saying this is definitely cau...
My step-up converter makes audible noise both with and without a load.I am almost certain it is the inductor, because when I hold my finger on it I can feel vibration and it gets quieter. Unfortuna...
General cause of noise/interference The interference can be distant (such as lightning) or much closer (such as cables connecting "other" equipment) but, whatever the source, interference can be re...
What benefit has a differential amplifier when measuring the signal from a sensor that is remotely located such as in this example: - Why can't I use an arrangement like this: -
Input offset voltage $V_{OS}$ Your problem might be input offset voltage or $V_{OS}$. This can be several milli-volts and manifests as this modification to your original circuit (in red): - So, fo...
I've built a non-inverting op-amp amplifier with a gain of 101 using this circuit: - My input is 10 mV DC and I expected to measure 1.01 volts at the output but I measure 0.81 volts. What has happ...
It doesn't quite work that way. You are missing the fact that the current (which the magnetic field is proportional to) decays exponentially. You are also missing the resistance of the coil itsel...
When switching a relay there should be a flyback diode. It could be just a diode or diode with resistor in series. I understand there is a difference in the speed of relay switch-off. But what is t...
RTOS A RTOS (Real Time Operating System) is much more than a bunch of interrupts. Most true dedicated microcontroller applications don't need any RTOS or any other kind of operating system. Genera...
To avoid shoot-through you should ensure that the active-low P-channel MOSFET gate drive voltage never overlaps with the active-high N-channel MOSFET gate drive voltage. With an inverter driving th...
I'm using a variable duty cycle square-wave oscillator to drive a half-bridge MOSFET pair like this. Upper MOSFET is P-channel type, lower MOSFET is N-channel type: - And, I think I'm getting shoo...
When should I consider using RTOS in my application? Every microcontroller has a good number of interrupts then what is the need of it?
Bootloader definition A bootloader is a program that runs in the microcontroller to be programmed. It receives new program information externally via some communication means, like a serial port, ...
I've heard that a bootloader is code that runs on a microcontroller, and is used to get your application code onto the micro. How does that work? Is there anything special that needs to be done to...
The lifetime rating is (usually) quoted as "so many" hours at a certain temperature and that is the crucial thing to be aware of. For instance, consider a capacitor like this one: - Some in the ...
Using pointer types In C, an object pointer such as uint8_t* ptr is the equivalent concept to use for hardware addresses. A compiler makes this pointer type large enough to contain all addresses in...
If you search through the electrolytic capacitor offerings from distributors like Farnell, RS, Digikey or Mouser, you find that the maximum life-time rating is commonly quoted as 5,000 or 10,000 ho...
When writing firmware in C for a microcontroller, how can I directly access a memory location such as a hardware peripheral register, given its absolute address? Is there a way to do this safely an...
What would be the main considerations to use Pi-filters for EMC? Using the filter correctly and understanding its limitations EMC or EMI (electromagnetic interference) is noted for its high frequ...
As an alternative to doing the math, as detailed in Andy's answer, you can use a graphical aid called a Smith chart: These were used routinely before computers to match transmitters to antennas. ...
Low-pass impedance transformation Theory Input Impedance: - $$Z_{IN} = j\omega L + \dfrac{\dfrac{R_L}{j\omega C}}{R_L + \dfrac{1}{j\omega C}} = j\omega L +\dfrac{R_L}{1 + j\omega R_L C} = \dfrac{j...
I have a signal at 10 MHz produced from a 50 Ω source. How can I match that to a 300 Ω load with low losses without using an RF transformer (space constraints)? Are there any circuits and formulas ...
Pi filters are often used to block high frequencies between a device and the power line it draws power from. In such applications, the considerations specifying the inductor include: How much powe...
First let's define what a "Pi filter" is: The name comes from the inductor and two caps forming the shape of the Greek letter Π. These filters are used for EMC compliance because they attenuate hi...
I have seen pi-filters using chokes, ferrite-beads, and plain inductors as the L-element What are the main differences between them? when use one or other?
