# All Questions

116,779 questions
56 views

### Converting between series and parallel circuits

I have an RCL circuit which which is coupled to an RC circuit via a coupling capacitor, $C_{c}$. When the system is on resonance, $\omega = \omega_{0}$ the impedance of the RCL is purely resistive,...
18 views

### How to return from SystemC thread with error code?

I've got a SystemC testbench (for a VHDL DUT but that's irrelevant right now). I'd like to be able to cause the test to terminate, with a specific exit code, from within an SC_CTHREAD. I am pretty ...
842 views

### What kind of capacitor is this in the image? [on hold]

The power supply of my model railway got broken. I think the problem is the capacitor shown in the image. So does somebody know which kind of capacitor this is?
39 views

### How to read potentiometer value in existing circuit

I built a circuit for heater controller and it works fine. I want to read poentiometer R3 values with microcontroller Arduino. I am not sure if I am doing correct way, but I connected Arduino analog ...
30 views

### UART communication between GSM and GPS

I want to establish a UART Communication between GSM module and a GPS receiver. The supply voltage of the GPS receiver is 3.3V. The supply voltage of the GSM module is 3.8V. The measured RX/TX ...
77 views

### How to produce sawtooth waveform from square waveform?

I have a question pertaining the changing of square waveform to sawtooth waveform using OpAmp. Following the picture below, I have to create a sawtooth waveform from a square waveform. It seems that ...
61 views

### How to differentiate between load and short circuit

I am working on a project. The goal is to differentiate between short circuit and load. I am trying to use differential amplifier. At load there are 2 to 3 millivolts. I need to compare them with zero ...
30 views

### HCPL3700 - 220V sensing circuit

I want to use HCPL3700 optocoupler for sensing 220V (line). I design a circuit but I want to ask some questions. HCPL3700 is an open-collector output so I pull-up Vout. In AC voltage sensing some ...
41 views

### How to find the best way to fade in/out?

I have a bunch of these PAR lights below. They work with DMX and have per LED PAR 3 red, 3 green, 3 blue and 3 white LEDs. I can set the value for the red, green, blue and white lights independently (...
27 views

### Dimming multiple led light bulbs (parallel or in series) [migrated]

I'd like to install 5 dimmable led bulbs. I'm trying to find how to connect them. But I can't get a clear answer. I can get information of the benefits of wiring leds in series/parallel but none of ...
58 views

### Simulation on LTSpice

LTSpice does not have a gap sensor as a component. Is there anyway I can either download a gap sensor or is there a way to create my own one.
7 views

### finding the minimal length of a broadcasting frame in a channel(CSMA/CD)

i am unsure about this question. would appreciate your assistance with it. in the following CSMA/CD network with cable length L and propagation T. assuming that the signal is not decreasing and there'...
32 views

### Spurious oscillation frequency of relaxation oscillator in between reboot

schematic:- c16 -> 0.1uf c17 -> 10uf R10 , R11 , R12 -> 4.7k R -> 20k c -> 47pf pcb layout:- on every reboot FREQ1 is either expected value of 600khz or its around 25mhz. If its 25mhz it stay ...
46 views

### MOSFET gate switching time

In high current boost converter (6-14A input, 5A output), how to determine optimal switching time for the MOSFET gate, to get balance between power loss and switching noise? I mean the time MOSFET ...
31 views

### Using PC as an interface between two serial ports [on hold]

I want to know how I can receive data from a virtual COM port (say COM9) and use it as an input for another COM port (say COM10) and vice versa.
42 views

### Ferrite beads for high currents

In the EVM datasheet schematic, two input beads and 2 output beads are used. In my application, I drive 56V 5A COB LED. Input voltage is 22-50V, so input current can be ~6-13A. I read on Internet, ...
49 views

### Microcontroller Wired-OR connection

I would like to connect several microcontrollers as shown in the circuit diagram below. The software makes sure that the PA1 pin always has the low or floating state. It's a kind of open drain ...
26 views

### Understanding PMOS's and NMOS's

The problem says solve assuming VI = 0, +2.5V, and -2.5V. I know that if VI = -2.5V the MOSFET's are in cutoff and that VDS = 0. and IDP and IDN will = 0, but would V0 also = 0? If VI = 0 the ...
11 views

### LPDDR4 pre-fetch

In the JEDEC LPDDR4 spec it is mentioned that LPDDR4 DRAM can support burst length 32(BL32) and also the LPDDR4 DRAM architecture is 16n prefetch. I want to know how burst length 32 be possible with ...
32 views

### How to connect a fast recovery diode with 3 pins?

I have a fast recovery diode, part number D30FD60K, I would like to know how I have to connect it. The diode will be used as the return path in parallel with a fuse. Like shown in the diagram. Pin 3 ...
12 views

### Image for S-M junction

Can you provide me a link where I can see how a S-M looks like in zero bias?Only think I can find are band diagramms.
13 views

### learn KPN remote control IR commands (Arcadyan)

When I try to have my Broadlink RM Pro learn the commands of the remote control of my KPN (Arcadyan) set-top box it does not recognize any of them. Why?
295 views

### Is there a right way of implementing a T flip flop in verilog wrt using reset signal?

I made a t flip flop using structural modeling in verilog. ...
52 views

### Controlling 1 fan with 2 different computer power supplies

Ok here is my scenario: Because our 2 gaming computers are pretty noisy, we moved them to another room in a closet. There are vent holes to the outside of the building, and now that the summer comes ...
34 views

### Converting 230V Ac to 12 V 5A or 10A DC Converter

I am not very familiar with SMPS circuits. But I have tried examples available online of transformerless circuits to convert 230AC to 12V DC but the current I get is very very low. I haven't found any ...
43 views

### Pulldown for zener voltage shifter

I would like to know whether R24 has been correctly applied to pulldown the EN pin when none of the diodes are switched on. The idea here is that voltages higher than 3.3V may be applied from any of ...
34 views

### ATX hard disk activity led wiring [migrated]

How is the hdd activity led wired according to the ATX specification? Is it like this? simulate this circuit – Schematic created using CircuitLab If so, what is the 5V voltage relative to? PSU ...
21 views

### 2000rpm with 5kg-cm torque

I need to make a lift system which raises and lowers about 2-3kg load as fast as possible and switch the direction every 2-3 seconds. Ideally, 2 m/s speed is very good. But for my prototype, 1m/s is ...
21 views

### stm32f4 sensor communication

We are using stm407vg and we have 2 SPI,2 I2C. Do we have to use mosfet circuit (to get level shift) for sensor communications. SPI connections supply 3.3 Volt. We are new in this area, could you ...
65 views

### How do I remove resin from an LED?

I want to get direct access to the top contact of an LED. How do I remove the layer of resin on top of the LED?
16 views

### 2:4 Decoder on LTSpice [duplicate]

LTSpice does not have a decoder component so I have had to make my own using two inverters and four AND gates. I am not sure if I have done it correctly.
17 views

### SIM800: AT-command to get connected sender ids

I want to roughly estimate where my Arduino currently is. For this, I want to fetch the identification numbers of the stations it is currently connected to, so I can put them into an API which then ...
106 views

### Why this circuit may consume some extra current?

I have this transistor circuit with relay. Here the transistor input is connected to the GPIO pin of the micro controller. According to whether this relay is ON or OFF, then phase voltage is passed (...
51 views

### is it possible to boost up the current by keeping the voltage constant?

I have a source that can deliver 20mA and 4.5V (MAXIMUM). I need to boost the current to 1 A without using any further source. Also, the voltage should be maintained constant at 4.5V. is that ...
10 views

### Simulation of decoders on LTSpice [duplicate]

I need to simulate a 2:4 decoder on LTSpice however the component does not exist. Does anyone know of a way to simulate it?
19 views

### LTSPICe time step too small

I am getting an error while trying to simulate the following netlist in LTspice. I am trying to simulate QISS (Gate charge curve) and see the Miller Plateau in MOSFET Autogenerated netlist at 22-Apr-...
23 views

### Simulation of decoder on LTSpice

I need to simulate a 2:4 decoder on LTSpice however I can not find the component anywhere. Does anyone know of a way I can simulate it?
66 views

### How to convert 220 VDC to 24 VDC

I’m working on a project where I need to build a converter/power supply for converting 220 VDC to 24 VDC. Yes, its 220 VDC not AC. This convertor will be mounted on a locomotive type vehicle ...
19 views

### PTC thermister value

I am trying to find out specifications of a thermister on which "10P" is printed. Its resistance at room temp. is 18 Ohms when the circuit is power off. How can I find out its specifications?
13 views

### Bluetooth Application File-Sharing [on hold]

Is it a practical application to use Bluetooth for file sharing? And is Bluetooth Mesh optimized for this application?
33 views

### How to tell if the switch is open or closed on a mains line?

Imagine a circuit that may or may not be connected to mains voltage. If mains is connected, it is trivial to determine if the switch is closed, by using a zero-cross detector circuit. If mains is ...
32 views

### Distortion is introduced when speaker is connected to the output of the amplifier

I have a circuit that implements a guitar amplifier (I ordered a couple LM386 but in the meantime I used an OP484). The following figure represents my schematic: (cap C2=10uF as well) The signal from ...
49 views

### Diode circuit analysis solution

I am not familiar with circuit analysis, although I can manage to solve basic circuit. However, I am currently stuck with a problem and I am not sure about the solutions. If anyone could have a look ...
30 views

### Inductance value of PI-filter connectors?

I find myself in the situation of being forced to use filter connectors to solve an EMC issue very late in the project. Normally, this should of course be solved in circuit design, but as projects and ...
20 views

### Avalanche relaxation oscillator biasing resistor

I've tried the circuit in this article. It works very well and I've obtained 2ns clear pulses at 150 V (the main issue was to find the right avalanche voltage, which turned out to be 150-160V for my ...
11 views

### DC motor simulation in ansys simplorer

I am doing simulation of DC motor in ANSYS Simplorer in which I need to insert following parameters in motor model: Armature resistance=0.115ohm Armature inductance=0.8479mH Rotor Flux=0....
36 views

### Confused on Fourier Transform. What is amplitude spectrum and phase?

I am learning fourier transform by myself and I am confused on the description below. I can't understand how can I get the second formula by using the Euler formula on the first equation. Why is ...
2k views

### IC on Digikey is 5x more expensive than board containing same IC on Alibaba: How? [on hold]

I built a prototype using an NFC board I bought from Alibaba for 1\$ (https://www.alibaba.com/showroom/rfid-rc522.html). It claims to use the NXP MFRC522 IC, and if I look on the board the chip has ...