# All Questions

113,201 questions
22 views

### Cascade shift registers driven by single-cycle microcontroller

I'm trying to make a unit in which 4 digits can be updated in a small amount of time from a single-cycle microcontroller (preferably all digits updated within 5uS) My circuit is setup in the ...
4 views

### Root Locus, Gain in Feedback Loop. Need help

So this is the system for which I have to draw a root locus if 'K' changes from 0 to infinity. The problem for me is that root locus is drawn for open loop transfer function but 'K' is in the feedback ...
161 views

### How to make LC circuit just using Capacitor and Inductor?

I am experimenting with inductor so I am looking for a simple circuit that will blink the LED with oscillator circuit. Basically turn on and off LED and finally diminish. How can I do so? For power ...
27 views

### Microcontroller overheating when sensor is plugged in

I am building a board based around an STM32L051C6 microcontroller, which will measure a hall effect sensor (AH3362Q) and count the time in between the edges the sensor sees. The sensor is powered from ...
43 views

### Methods to measure inductance with high (1%) precision using standard equipment?

I am modeling the fine behavior of interacting oscillatory circuits. I have looked up a couple of methods for measuring inductance. I believe I am following the procedure faithfully, but the values I ...
19 views

32 views

### Alternative to alternating relay? or help?

I'm using a littelfuse relay shown in the link to switch motor directions. I'm sending a pulse to the relay switch of 0.02s in order to switch between the L1 and L2 contacts. The pulse seems to be too ...
44 views

Is is true that the magnetic field generated by a conductor conducting around 20A will not be sufficient in order to provide an EMF of around 3.3V? The frequency of the AC signal is 50Hz. Based on ...
39 views

### How to use a transistor to drive strings of LEDs from GPIO pins?

This is similar to How to drive a 20mA LED From a 4mA max GPIO Pin except that I need a little more hand-holding in order to understand what is happening. For background, I'm a software engineer and ...
7k views

### What exactly is voltage?

Bit of a strange question, but what is it? My physics teacher said it was kind of like a "push" that pushes electrons around the circuit. Can I have a more complex explanation? Any help is much ...
127 views

### How to find out what level of battery voltage corresponds to 50% discharge?

In my off-grid solar system I am using 12V lead-carbon batteries capable of surviving 4000 cycles when discharged up to 50%. Capacity is 200Amp-Hours (100 Hour discharge) per battery. There is no BMS ...
146 views

### 10 resistor voltage divider calculations for LM3914 IC

I need to calculate the voltages on the 10 resistor voltage divider (V1,V2,V3...), but i don't know how to work it out. So far I found V1 by doing $$V1=Vs*(R3/(R3+R2))$$ and found V1= 0.5 Volts. Can ...
20 views

### iPAQ Backup Battery Connector

I've used an H4155 on and off for about a decade now and every two years or so the backup battery begins to increase in standby voltage and fail. I prefer to replace it just for the sake of it ...
13 views

### Iterative CORDIC algorithm dynamic shift optimization

I've implemented the CORDIC algorithm on an FPGA using an iterative approach. The component is loaded with a set of values to calculate and then iterates as many CORDIC steps as necessary for the ...
27 views

### How important is op amp supply cleanliness?

Say I have a simple non-inverting amplifier op amp application as shown. The input signal is far from the rails. Now say the +12 and -12 V supplies are not ideal DC, but rather have lots of ripple or ...
47 views

### Blink 3 LEDs at 1 Hz with a Power up ON Time Delay

I am very new to Arduino! I am struggling to create an Arduino program that would blink 3 LEDs with 1 Hz rate with an initial ON time delay for the 2nd and the 3rd LED. When the Arduino is switched ...
892 views

When you have one resistor in a series circuit, the amount of voltage taken up by that resistor is 100%. Adding another resistor (same Ohms) makes that voltage drop 50%. Why, since only current should ...
45 views

### Noise on my oscilloscope when probing a wire

I am prototyping a NTC voltage divider circuit and I am having trouble with noise on my probe. It seems like I am constantly getting a large amount of noise (200-300mv) on my oscilloscope waveform ...
154 views

### Motor controller voltage dropping to zero when under load

I'm having a problem with my KBMD DC motor controller. When no motor is connected, it puts out 0-90V, depending on the speed dial. However, when I attach my 1/40hp 90V DC motor, the voltage drops to ...
45 views

### Detect if an electromagnet it touching metal (without a switch)

I have a simple 12V DC holding electromagnet connected to a microcontroller using a MOSFET - the once you buy on aliexpress or eBay for cheap [1]. How can I detect if the magnet is in full contact ...
858 views

### What does a black bar across transformer symbol designate?

What does a black bar across a transformer symbol designate? This appears in a power electronics context, and in particular in this case with substituting a DC transformer as an equivalent circuit ...
40 views

### Crosstalk between AC and DC

First time asking a question but I've come across something I just can't find the answer to. Whether or not it's because a silly question I hope to find out. So I understand that with crosstalk ...
129 views

### Connection problem, BUS or Wire? - Altium Designer

I'm trying to make a panel with 1000 LEDs divided in two groups of 500 units and I want to put my schematic in A4 page. To do this I'm trying to use blocks, in this case 250 repeated blocks, separated ...
82 views

### Control the RGB tape with only one output of the microcontroller

I need to control the colors of an RGB ribbon. This requires 3 PWMs. But I have only one output of my microcontroller available. So for this I need to find a circuit that stays between the ...
66 views

What happens to STM32F407 ADC if i give it an input voltage higher than maximum VDDA that is mentioned in datasheet equals to 3.6 volts? It will harm the micro?
691 views

### Altium custom shield as component, allow other component to be inside

I'm creating a shield for arduino and to avoid recreating it in future, I created its base as component(both schematics and pcb) and only added arduino header pads in it. Everything is just working ...
46 views

### Light bulb LED equivalent of a CFL (Compact Fluorescent Lamp)

If I have a CFL light bulb of 100W what would be (how many watts ) its equivalent in LED. In the place where I live LEDs have taken over and CFLs are no longer available, but I need stron bright ...
29 views

### Standards for conducted EMI testing

I have some doubts to interpret the CISPR standards, one of them is in relation to the test environment for EMI conducted (150kHz up to 30MHz). The minimum size indicated for the vertical or ...
150 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 ...
30 views

### Programmatically Controlling RGB Arcade Buttons?

At my school, we're putting together an arcade cabinet that we're going to program our own custom games for. The one thing I cannot find is an RGB LED controller that is programmable from code, ...
30 views

### How to send a digital signal when analog sensor (QRE1113) reaches a threshold value without resorting to wasting analog input pin?

I'm building a miniature pinball machine and I am attempting to use an infrared reflector sensor (QRE1113) to detect when the ball rolls over it (I got the original idea from Ben Heck's videos). In ...
32 views

### Monitoring Health of VFD

Good day, Is there any method or external measuring tool that can be used to monitor the health status of a VFDs perdiodically?
58 views

### What should I look out for while buying an alternative battery for my mobile phone?

I have a mobile phone, the battery of which is now dead. The specifications of the battery are as follows: 3.8V, Li-Polymer, 2500mAh, and 9.5Wh. Since the manufacturer doesn't produce this battery ...
26 views

### How to set mfrc522 antenna to lower frequency

I have "Electronic Hotel Door Lock" It work with NXP mfrc522 module with mifare 1K card and have work with 2*1.5v battery. with this battery "Electronic Hotel Door Lock" open door for 4 month. I ...
17 views

### How to use Altium Multi-Board to define SODIMM board and socket connections?

I am attempting to use Altium 18.1.9's new "Multi-Board" feature to connect a 200-pin SODIMM board ---> to a SODIMM socket connector ---> on my mainboard PCB. This Altium article is just about the ...
2k views

### PCB base copper weight vs plating thickness

I am using Saturn PCB Design to help get the trace geometries to implement PCB differential characteristic impedances. I have some dimensions from the board house: But I am confused on how to input ...
96 views

I'm trying to make it so that my STM32L011 can jump from user code to the ST bootloader that allows flash to be reprogrammed over USART2. This is hypothetically the same question as STM32F091 Jump to ...
23 views

### Multiple boost converter voltage pulled down

I need to make a simulation of multiple boost converter design for different load ratios. I have designed 2 boost converter both of them have same duty cycle and same L and C values. Voltage input is ...
149 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-...
43 views

### How to estimate timing contraints for FPGAs?

I try to find out how to specify the timings restrictions in FPGA designs correctly (in .sdc/.xdc files). I know what setup and hold times mean. However: How do I find out, what timing constraints my ...
79 views

### Three phase AC machine

I have encountered a three phase ac machine whose name plate contains following information: Y/360 V/90 Hz/2,3 A. I don't know whether it is an induction machine or permanent magnet synchronous ...
24 views

### DIY ATX PSU turns off when attaching load on 12V rail

I want to convert my old ATX power supply to a simple bench supply for 12V devices. On the label it says it's a 300W PSU where I can use 264W on the 12V rail (see image below). https://imgur.com/...
17 views

### Room lines stills on my pcb and the top layers tracks are not displayed in 3D view, Altium

The fact is that I have routed. I would like to know how to proceed when this kind of thing happens when using altium. The routed tracks can be seen perfectly in 2D view. But when click 3D view I can ...
29 views

### CAN Module(MCP2515) interface with Arduino

I connected the Arduino with an electrical meter using MCP2515. But ever time I am getting same. . The value in the meter is 12.0. Even I tried different data register which has value 0.0 but still, I ...
38 views

### Fixing an old fan wiring

I picked up this old fan which is apparently not working. I don't know much about electrical engineering but I can solder and connect cables and wanna hope that the problem is small enough to allow me ...
145 views

### Single phase 2 speed blower motor controller

I burn wood and salvaged an old 1/20 hp 1550 rpm two speed GE single phase motor (5KSM59CS12K6AS if anyone can find more info, curious what speeds are). I'm trying to make a digital fan controller ...
53 views

### Is my radio pulling more current than it should?

I have an FT-747GX radio that I am using as a RF generator for a plasma cleaning machine. In the operating manual on page 3 it states: I have a power supply connected to this radio which outputs ...
38 views

### Isolated voltage sensing

I'm in the process of building a battery powered, uC controlled power supply. I'm using a bluepill basically and an xl4016 buck converter module. To my assumption I can just tap in his regulation pot ...