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15
votes
0answers
693 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 ...
10
votes
2answers
298 views

Contact a very small area (impedance matched)

In my current project, I want to apply a voltage to a capacitor (top electrode on a thin film heterostructure) very rapidly. Since capacitors have their own charging rate \$(\tau = R \cdot t = R \cdot ...
8
votes
1answer
899 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 ...
7
votes
1answer
260 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 ...
7
votes
2answers
279 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 ...
6
votes
1answer
162 views

How to generate different noise in LTspice from run to run

I'm trying to simulate noise in my circuit, and ideally want to get a histogram of a certain parameter affected by that noise over many runs. However, when I use the white() command in LTspice, or ...
6
votes
1answer
272 views

DDR3 Data Errors

I am looking for post layout solutions for DDR3 data errors. I have a PCB with a FPGA and a 2 banks (2 rank) DDR3 ram setup. Data errors occur either when the RAM (FPGA is not confirmed, but could ...
6
votes
0answers
152 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 ...
6
votes
1answer
204 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 ...
6
votes
1answer
889 views

Receiver issues on STM32H7 interrupt-based SPI

I want to configure a simple interrupt-based SPI slave transmitter/receiver on a STM32H7 MCU. Even though I have quite a bit experience with the older series of STM32 ARM MCUs, it seems that a lot of ...
6
votes
0answers
205 views

Incrementing net name for group in Eagle

I want to make 50 copies of the block below, but I need incrementing numbers on each of the net labels (these will go to a connector). I do not want each block connected to the other blocks. It would ...
6
votes
1answer
456 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 ...
5
votes
0answers
145 views

Analyze protocol used for Futaba VFD display, 3 data pins

I take apart a Samsung SMT-C7140 HD Unit (made obsolete by cable company, a shame) and found a nice display that I could probably reuse. It is a Futaba GL07-00006A (13-BT-246GINK). I tried to find the ...
5
votes
1answer
204 views

How do I calculate a PCB antenna trace width?

I'm totally stuck here trying to find a single source that describes how to determine a PCB antenna trace width. I understand how to determine the length based on the targeted wavelength, but the ...
5
votes
1answer
168 views

Circuit stable in the Bode diagram, unstable in step-response

I am designing a simple current control circuit and trying to simulate it in LT Spice. The circuit is not optimized for some real-world application, it's more a learning method for me to get grip on ...
5
votes
3answers
223 views

How can I realize this nonlinear resistor?

I want to know if it's possible to realize a circuit described by the equation $$I = \sin(w V)$$ where \$I\$ is the current, \$V\$ the potential and \$w\$ a variable which characterizes the single ...
5
votes
0answers
121 views

Photon count with ADC, am I doing it right?

I have this LED and I want to characterize this photodiode. The LED should produce light of 370 nm, but I measured it and it is around 358 nm, and at that wavelength the quantum efficiency (\$\eta\$) ...
5
votes
0answers
79 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 ...
5
votes
0answers
317 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'...
5
votes
1answer
130 views

Headphone Noise from Laptop SMPS

I have been facing an issue that has been a mystery to me for quite some time, and I wanted to see if someone here can potentially give me more insights on this so I can understand why it is happening....
5
votes
1answer
294 views

Recommendation for series protection resistors on CAN bus?

When implementing an RS-485 interface, I tend to follow TI's recommendation in the SN65HVD75 datasheet to include \$10 \Omega\$ series resistors on the A and B lines. The TVS diodes I'm using clamp ...
5
votes
1answer
620 views

Safety Capacitor Selection

When selecting an X2 safety capacitor what must be taken into consideration. There are only a few types of capacitance ranges and seem to be chosen based on voltage rather than capacitance. Take ...
5
votes
4answers
651 views

32.768 kHz Crystal Troubleshooting

I'm at my wit's end trying to get a 32.768 kHz tuning fork crystal to work and I don't know what I'm doing wrong. First, some background: I'm using a 16MHz crystal in conjunction with an Atmega 328P-...
5
votes
3answers
3k views

Calculating the ESR of Capacitor

I try to calculate the ESR of a capacitor. I checked this datasheet: http://www.farnell.com/datasheets/2245214.pdf?_ga=2.167304311.817060034.1534770853-676261198.1531404202 I can see from the ...
5
votes
1answer
391 views

Designing single fault safety into class I device

I'm trying to wrap my head around safety standards for electrical equipment. My device is medical, so for me section 8 of IEC60601-1 is what really matters to me, but it's kind of my understanding ...
5
votes
3answers
883 views

Efficient 60v to 12v DC-DC

I'm on the process of building a new version of my ebike electronic systems and I'm searching for a way to lower the voltage of the battery (13s = 54,6v fully charged) to 12v/5v for the accessories ...
5
votes
1answer
8k views

How can I model this common mode choke in circuit in LTspice?

How can the common mode choke in below diagram used in LTspice? By an inductor or transformer? How should be the circuit drawn in LTspice? I want to use this to filter out CM noises for single ended ...
5
votes
1answer
747 views

Is it possible to use Microchip's ZCD (Zero cross detect) circuitry in an isolated SMPS?

Let's say you have a device which is fed by AC line voltage and features an isolated SMPS. The switcher outputs 5 VDC, and that powers a PIC micro. I'm curious how is the Microchip's ZCD (Zero cross ...
5
votes
0answers
6k views

Altium Designer: Polygon does not connect to the pads on the same Net

I'm trying to put a plane shield using polygon pour and I realized that some object is not connected to my polygon. In the picture below it is clearly seen that the GND through hole is not connected ...
5
votes
0answers
353 views

What is the 3D radiation pattern of this chip antenna?

I know that the 3D radiation pattern of an antenna could be found by knowing the xy, xz and yz plane cuts and vice-versa. This process is pretty straight forward for a dipole antenna which has a 3D ...
5
votes
2answers
651 views

Lifepo4 current limiter with supercapacitor in parallell

I am making a LiFePo4/supercapacitor-hybrid. Spike current draw can reach 300A for a few seconds. The LiFePo4 batteries I am using is rated for 100A max discharge rate. In order to make sure the ...
5
votes
1answer
425 views

MCU HIB pin only pulls Buck/Boost EN pin every-other Hibernation

MCU: TM4C1294NCPDT Buck/Boost Converter: TPS63051 Hib dedicated LDO: MIC5504-3.3YM5-TR I have a LiPo battery coming into the board, feeding both the TPS63051 and the MIC5504. Tiva's HIB pin is ...
5
votes
0answers
188 views

Help with deciding my layout for EMC tests and SI. Different alternatives

I am thinking of what way would be the best to layout my system in order for it to have the best SI and pass EMC tests. My system consists of two PCBs joint by a flat flex cable (up to 7cm) and these ...
5
votes
0answers
262 views

Setting up T2080 to FPGA PCie DMA

I'm doing an FPGA design using a T2080 MPC interfacing to an Altera Cyclone V FPGA. The goal is to use my FPGA to pump 2 other FPGAs on the same board. I need to create a scheme that allows the ...
5
votes
0answers
217 views

Home made passive tablet pen

I have an old wacom tablet at home, its really big and I'd like to use it but I've lost the pen for it. It uses pens with passive LC circuitry. The board creats an EM-field (I can see it on my ...
5
votes
0answers
130 views

Testing strategies for testing a Scheduler

We have developed an in-house Scheduler which is based on Rate-monotonic scheduling. We have 6 tasks (5 actual tasks and 1 idle task). Our scheduler works on 1msec timer interrupt. Before sending it ...
4
votes
0answers
112 views

LEDs blinking circuit problem

I tried the following circuit but the LEDs for me are always on and don't blink, i checked connectivity, changed capacitors and tested transistors but same problem. what could be the issue? edit: ...
4
votes
1answer
103 views

Tuning of a PID loop for heater element

I built a controller for a soldering iron (JBC C245/C210 specifically), which can supply up to 60W of power to the iron. I have a temperature control loop that runs at 10 Hz, which I am trying to tune ...
4
votes
1answer
69 views

36x LED 5730 in series: diodes burnt when LED driver (based on BP9833A or MT7854BD) powered up

Background: I have 18W, 36 LED lamp fixture which I cannot change. Originally it has 2x parallel 18off 5730 LEDs and 300mA driver. It works for some time, but diodes starts burning. I thought that ...
4
votes
2answers
172 views

Low power tube headphone amplifier design

I have never worked or even listened to tubes/valves before, so its about time I did. I wanted a simple design to work with being my first tube project, and have found this from diyaudioprojects.com: ...
4
votes
1answer
700 views

Why does the UPS mode of an inverter have faster switching times?

Of all the sinewave inverters I have used, they contain a switch at the back labelled Normal and UPS. When you put the inverter in normal mode, there is some 40-50 ms switchover time, enough to make ...
4
votes
0answers
169 views

Feedback Topologies

This is my homework problem. I tried to solve this problem but i got it wrong. Here is the problem: As it is clear from the circuit that we are taking voltage at the node V0 and some fraction of ...
4
votes
0answers
215 views

What is causing this weird effect with aluminum?

I grabbed an LED and then scraped an aluminum plate with a pin, and it turned on at some points, at first I thought it was electrified but it wasn't, then I tried with another aluminum plate and it ...
4
votes
0answers
113 views

ATTiny85 clock speed problem

Using an ATTiny85 and an Arduino loader I created a simple device for turning on an exhaust fan based on a light sensor. The ATTiny85 turns on the fan after activating a warning light and sounding an ...
4
votes
0answers
135 views

Non-inverting op-amp saturating incorrectly

Background Hello, I'm trying to amplify an audio signal using an LM324N in a non-inverting configuration. I'm not trying to build an audio amplifier to drive speakers, I just need to amplify it a bit ...
4
votes
0answers
454 views

Adding foot control to tig welder

I've got a simple tig welder that uses a switch on the torch to start the welding current and a potentiometer on the front panel to set the amperage. Many welders make use of a foot pedal to start te ...
4
votes
6answers
254 views

What is the value of this 5-band resistor

The colors are black, light green, green, red and silver (looks more like gray). I am not sure which side to start reading the values from. Both ends seem to be symmetrical. Moreover, I have never ...
4
votes
0answers
229 views

Modeling scalar control of PMSM

I have met with a scalar control algorithm for a permanent magnet synchronous motor. I haven´t heard about it before so I decided to develop a dynamic model to further analyze this control algorithm. ...
4
votes
2answers
700 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: ...
4
votes
1answer
349 views

How can I reshape this PCB antenna so that I can still use it with the given circuit?

I'm borrowing the RF design from the MICRF114 Development Kit. Here's user guide- http://ww1.microchip.com/downloads/en/DeviceDoc/50002433A.pdf The circuit I'm using is on p. 35 and the antenna ...

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