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The small signal analysis of a BJT when the BJT is in amplification mode: is easy.However what happens when the BJT is in saturation mode? Can we replace the dependent current source with a r...
First I noticed that clock begins before chipselect gets pulled low on SPI. After eliminating potential sources I started to suspect the scope. I connected all 4 channels to function generator at d...
I am trying to find the AC analysis of a BJT Hartley oscillator but I cannot continue. How do I find the voltage gain? When no feedback is there, we just find the output resistance and the current...
I am designing a low-pass filter with cut-off frequency = 100Hz and after the cutoff frequency from -3dB to -10dB the average decrease in db/Hz = -0.1 db/Hz.I know how to design a low-pass filter ...
Signals with frequency above the cutoff frequency of a transmission line cannot be transmitted through the transmission line. But how can I calculate the cutoff frequency of a single phase transm...
I was studying the Re model of a transistor: But the Re model for 2 different configurations (common emitter and common base )turns out to be the same! I don't know why I am really confused.How...
I have designed a PCB that I need to work in which a microcontroller drives a 24 V brushed motor. The input power to the board is 24 V, this is then lowered to 5 V by a step down converter, and thi...
I was watching a video from EEVBLOG about bypass capacitors, and he presented a theory that randomly connecting different values of capacitors in parallel can create unexpected impedance spikes: ...
I saw that equation of reactance is written like this $$I=\frac{V}{|R+X_L j|}$$ $$I=\frac{V}{|R-X_c j|}$$ When there's capacitor and inductor in a single circuit then it is written like : $$I=\...
I'm designing a high side current source that can be controlled with a Digital-to-analog and can source up to 100mA with voltage supply up to 36V. By high side I mean one side of load will be alwa...
Which important system design parameters need to be locked in order to estimate the maximum allowable level of the input voltage ripple of an SMPS? I have encountered ballpark figures of <1%, &...
I saw that this PCB socket: Is marked as pressfit for non-plated holes. However, can it be used with plated holes as well, or will it damage the plating inside?
Suppose we have a sine signal applied to a inductive load. Is the inductance of the load changed if the frequency of the signal is changed?
The premise In a recent video by the pop-sci channel Veritasium, the concept of the flow of electricity and energy transmission in a circuit was discussed. In that video a thought experiment is pr...
I was looking at different transistors, especially MOSFETS and I saw that N type MOSFETs seem to be way more popular to be used in circuit design. Is there a reason for that, or am I mistaken?
I recently started working at a construction office in another country. I usually listen to music when working, and I saw a headphone jack in the wall, so I thought it is radio or something, I plug...
I have designed a graph of the current in a photoresistor related to the brightness of light which hits the photoresistor. Our professor told us that it is more correct to draw the Current/Brigh...
As we know there exists numerous different kinds of PCB CAD software. The big ones seem to be Eagle, KiCAD, Altium, OrCAD, Solidworks, DesignSpark and probably a few more. When it comes to mechani...
RF novice here. If using a superheterodyne receiver for the purpose of FM/FSK modulated signals, I'm wondering if the location of an optional automatic gain control (AGC) circuit is always placed o...
I need to design a simple flyback converter like this: - I want to control duty cycle from another circuit such as an MCU but, I'm unsure how to proceed. My requirements are: - Input voltage 125 ...
I have a PIC32MZ2048ECG064, a 64-pin 32-bit microcontroller with 512kB RAM. This is not enough for my purposes, I need to extend it by at least 32MB, preferably 64 or 128. I believe this means I ca...
On the LEFT is what I just bought today — Globe Electric 4W (40W Equivalent) Daylight (5000K) Dimmable LED Light Bulb, G9 Bi-Pin Base, 400 Lumens, 15,000 H. Here's Globe Electric's Dimmer Compatibi...
One standard used for spacing conductors based on voltage is the IPC-2221. This standard differentiates spacing requirements for inner and outer conductors. Does the IPC minimum separation betwee...
Differential pairs, such as for ethernet or a CAN bus, can be designed to be loosely coupled or tightly coupled. For a loosely coupled differential pair, the odd-mode and even-mode impedances are ...
I am designing a PCB with somewhat limited space. To save space, I am placing some vias on component pads. However, I am not sure if this is a good practice in PCB design. As far as I understand, t...
In a 3 phase Star source-Star load circuit the phase voltage has different phase than line voltage and in a 3 phase Delta source-Delta load circuit the phase current has different phase than the li...
Assume a app generates a message (stack on computer).Each layer of the sending entity will put then control information in the data depending on the protocol and transmit the data to the next lowe...
The question: Is there a way to convert from triple-phase 208VAC to single-phase 208VAC? Background: Hi everyone, I am stuck on a project I'm working on. I'd like to convert 208VAC (three phase,...
I have a handheld ARM Cortex M based device, which has a USB input port. The product is battery powered and there is no metal chassis. We are going through CE testing, and are having ESD issues a...
In this datasheet it says that the minimum resolution is 0.1uA for the 10mA range.What is this minimum resolution?Is it the sensitivity of the multimeter for the 10mA range?
Can we find the internal resistance of a multimeter ,when we use the multimeter like a ampmeter, from its datasheet? I am trying to find the internal resistance of IDM 505 and I went to the datash...
I'm wondering if there are particular aspects of an oscilloscope probe's performance that tend to suffer, or failure points to look out for, if/when buying lower-end makes of oscilloscope probes (l...
The circuit above is used to control a 240W ceramic heater by means of a PWM signal at 30Hz, generated by a microcontroller, with 5V logic. The input is a standard 280W AC-DC external power adapt...
Hello everyone, I have a simple circuit in which I control some LEDs via an MCU and DMG2302UK ( N-channel MOSFET ) The EN pin is connected to an MCU gpio pin that works at 3.3V. The circuit wo...
A while ago I made a question about the monostable multivibrator .Lets get a picture of it: When switch is closed it enters its unstable state and it eventually returns to the stable state Howe...
Assuming we have a voltage regulator : Why do we have to ground Vin and Vout using 2 capacitors just like that?Co could be to provide a low resistance path to GND at high frequencies but what is...
I have this circuit: I think that R3 acts like a feedback path from the output to the input.However I am not sure what will happen if I change the value from 100Ohms to lets say 1kOhms. I have ...
I'm wondering what's the most correct term (if any) to use for "switching noise" of a radio transceiver? By that I mean the spikes that originate from turning the power amp on/off while switching b...
I'm designing a PCB for a project. 12 volt input power supply is provided externally, so the user will buy a power adapter, so putting a popular DC jack on the PCB is the best choice.
Modern CAN transceivers like MCP2561FD that support CAN FD with high baudrates come with an optional feature called SPLIT, which is to my understanding a reference voltage output pin used to give a...
Is it possible to drive a PMSM motor - here I am referring to an AC motor with permanent magnets(stator wounded, rotor with PM) - in a way that there is no externally mounted rotor position sensor(...
Hello I don't understand how this differential to single-ended voltage converter can work. What I don't understand is why we place a current mirror(a current mirror copies the current flowing thr...
In monostable multivibrators we use a trigger signal applied to the base of the transistor which is usually off to enter the astable region Can we instead have a pin which is connected directly ...
What is a typical value for capacitance of a real inductor? Does this internal capacitance exist only under AC and not DC?
How does the differential to single ended converter work? In order for the circuit to work, Q1 and Q3 must be in the saturation region and depending on the voltage inputs, one of Q2 and Q4 will be...
How do I find the current through the inductor and the voltage of the inductor after the switch is closed?
How do I find the voltage of the capacitor and the current through the capacitor after the switch is closed?
What is a difference between SPI stream and memory mapped SPI? PS SPI is a peripheral.
When using through-hole ("THR") connectors on a multi-layer PCB, I frequently notice problems with the ground pins, when these are connected to the ground plane(s) through various "thermal relief" ...
