# All Questions

14,088 questions with no upvoted or accepted answers
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722 views

### Increasing the compliance voltage range for a variable, two-quadrant constant current pin-driver circuit

The following is for hobbyist work and I have no commercial intentions at all. Only a handful (two?) will be built. (I use these for part testing and curve generation, though with the higher voltage ...
3k views

### DRC tool for Gerber files

Do you know any tools which perform design rule checking for Gerber files of PCB and are suitable for using in batch mode on a remote server? Something similar to what BatchPCB or FreeDFM uses (I ...
337 views

### Switch from JTAG to SWD with bitbang sequence on STM32F103VB

I am trying to switch from JTAG to SWD without any external devices. Why? Because I would like to use the SWO pin to send a stream of logging information to another device. To accomplish this ...
331 views

### Digital Signal Cables Penetrating a RF Shielded Room

Disclaimer: I'm not a trained electrical engineer...I'm a recent Computer Science grad with about ten years experience as a RF test tech. I don't know everything, and to me, experience reigns supreme ...
170 views

### Which part of some LED TV screens acts as two gratings crossed at non-straight angle?

Some modern LED TVs display the following diffraction pattern (photos taken from this question): In my answer to another question about the origin of this pattern I explained that this should be due ...
4k views

### STM32F407 + LAN8720A + lwIP + FreeRTOS = No received Ethernet frames

I'm trying to bring up a PCB that uses an STM32F407 and LAN8720A Ethernet PHY, and I can't seem to receive any Ethernet frames — even though I have no problem transmitting frames. Hardware setup I ...
4k views

### Stability factors of a voltage divider bias circuit

I am trying to derive the stability factors of a voltage divider bias circuit. I could derive S,S', however, I'm facing some problem with the derivation of S''. Please help me in this regard. How to ...
133 views

### Compute spatial integral using analog computing

Let me start by saying that I am not an electrical engineer but a mathematician, who just started to dive into the world of analog computing using for the moment Simulink to simulate an analog ...
90 views

### Voltage Controlled Current Source - help needed

I am designing a voltage controlled current generator for the currents in a range from 0 - 2.5mA. The load resistance is within the range of 0 - 5k Ohms. I decided to go with difference amplifier ...
286 views

### Design of cavity filter

I try to design a Chebyshev bandpass filter for 6 GHz as a coaxial cavity filter. I know that the filter can be designed with the aid of the coupling coefficients between the resonators and the loaded ...
497 views

### LM386 guitar practice amp circuit not working, need help finding mistake

I'm very new to electronics and I built this guitar amp circuit on a breadboard: and it was working really nicely. Now I've decided to put the circuit on a universal PCB which I'll use in the actual ...
433 views

### GPS Power consumption MTK3339 vs SirfIII for periodic logging application

I am currently working on redesigning a SirfIII based battery operated GPS logger. A MTK3339 based GPS module has been selected due to overall (advertised) performance. The GPS logger uses a ...
243 views

### ARD00280 Microchip Energy Reference Schematic Live and Neutral Swapped?

Looking at the Microchip Energy Chip reference design I noticed that the power is being sampled from neutral. My first reaction to this was this is backwards, that the power should be sampled from ...
65 views

### “Temporary boost” supercap

I have a 12VDC load (up to 10A) that functions correctly down to 8VDC. Sometimes (frequency: many seconds max, many minutes typical) the power source has a very brief (few milliseconds) drop to 7V. ...
125 views

### Removing output voltage ripple in high voltage outputs

I am looking to reduce the voltage ripple on a DC/DC converter operating at 5kV. I have looked extensively on the internet and have found multiple ways to reduce output voltage ripple, an ...
178 views

### Is JTAG faster than SWD for debugging on an STM32F with STLINK-V3SET programmer?

There is a new STLINK-V3SET programmer that someone dropped off on my desk today. It supports USB 2.0. My thinking is that if SWD is the bandwidth limiter in the signal chain then a new programmer isn'...
97 views

### Can somebody please explain to me the principle of a T-T Earthing system?

How are the transformer, consumer's side and the generator earthed in a T-T Earthing system? I seem to understand that the generator and its frame should be earthed separately; The neutral of the ...
269 views

### How to calculate the impedance of a rectifier?

I am working on RF energy harvesting. Now I am trying to calculate the impedance of the rectifier, in order to do the impedance matching. An antenna (50 ohm) receives RF signal (915 MHz) and finally ...
95 views

### Altium testpoints auto-placement

Is there a way to use Altium to automatically generate test points on an already routed board? When there is no usable via, I'd like to place a pad on the net. When reviewing Altium API reference ...
273 views

### Ultra Low Consumption White LED Flasher

simulate this circuit – Schematic created using CircuitLab I need an LED flasher circuit to operate inside small model lighthouses. Ideally the flash needs to be white and the battery needs to ...
307 views

### High-Level Synthesis (HLS) vs RTL for ASIC flow

I'd like to know when it's a good idea to use HLS over RTL (Verilog/VHDL) design if I'm targetting ASIC implementation? Can synthesis tools like Design Compiler convert HLS C/C++ into gate-level ...
951 views

### How can I simulate an NTC on LTspice?

I have a schematic for a temperature controlled device which should operate at a particular temperature. For that I am using an NTC, now I have done the math by hand but it is more efficient and ...
121 views

189 views

### Is this a reasonable, robust way for detecting voltage crossing a threshold?

Updated, functional design at the bottom of this question I wish to detect when a low-impedance signal is below or above 60VDC (±3V). When the signal is above 60V, I'd like to indicate this by ...
59 views

### What is the relation between resonance frequency and piezoelectric charge coefficient?

We know that the maximum power is lost at the resonant frequency,where the impedance is minimal. On the other hand, when the impedance is minimized, the charge coefficient is maximized. In resonance ...
82 views

### Radio module resetting when fluorescent tube switched on/off

I have a PCB powered by an IRM-30-12 power supply (230VAC to 12VDC). On this PCB, I have a MRF24J40MD from Microchip and a Udooneo to drive it + a 5VDC regulator and the 3.3VDC of the Udooneo. After ...
106 views

### VHDL Procedure - Same variable for input/output parameter

I've written a component where I use the same variable for the input and output parameter of a procedure. A reduced example looks like this: ...
95 views

### Subthreshold Analog Accelerator - How is current derived through two sub-threshold transistors in series?

Was browsing the following paper: Fick, Laura, et al. "Analog in-memory subthreshold deep neural network accelerator." 2017 IEEE Custom Integrated Circuits Conference (CICC). IEEE, 2017. When I ran ...
152 views

### What determines the frequency of network cable

You have Cat6, 23 AWG, rated for 250Mhz frequency. You then have Cat6a, 23 AWG, rated for 500Mhz. Both are unshielded. How is Cat6a able to transmit data at a higher frequency then its counter part? ...
208 views

### What antenna is this?

I just disassembled an external FM antenna designed for an old Asus laptop. I expected to find some circuitry and a monopole or some other simple antenna. However, what I found was the antenna shown ...
174 views

### Is probe compensation of a scope only for 10X setting?

I can understand that the idea of probe compensation is to make the sensed signal to be frequency independent as shown below 9C * R = R * 9C: Does that mean that probe compensation should be done ...
216 views

### How to cure SMPS output to get upset by a switching device

I have been having ringing spike issues at the output of SMPS power supplies. I don't know what is this phenomenon is about but it is definitely related to switching devices on the same electrical ...
302 views

### Undefined signal in simulation

I am trying to verify a design written in VHDL using SystemVerilog's assertions. however I got a problem when I have a non defined signal'X' Just for example here is a code of a Comparator: ...