Questions tagged [qucs]
For questions about the Quite Universal Circuit Simulator (QUCS) open source circuit simulator package.
33
questions
2
votes
2answers
131 views
How do I find the -3dB point on a given graph
I just performed an AC Simulation on QUCS and was asked to find values of gain and phase at low freq. and high freq and at the -3dB frequency point with the roll-off slope. The circuit is an RC ...
0
votes
0answers
10 views
simulate a thyristor triggered load having a RC branch
In the following picture you have a simulation to figure out the voltage on a Thyristor triggered load. The current of triggering on the thyristor gate is 300 mA. What I am looking for is a signal on ...
0
votes
1answer
38 views
Diode doesn't work in a [attempt of] power supply simulation with QUCS
As a simulation exercise, I am trying to work out a power supply and actually I am at the point provided in the figure below
There is a message of error which I don't understand, but I realized it ...
2
votes
1answer
146 views
Non-inverting UA741 opamp simulation on QUCS
According with instructions provided here https://www.youtube.com/watch?v=dBY1k5qK2w4 (in Spanish), I tried to simulate an inverting opamp configuration, but I couldn't figure out the right vout ...
0
votes
0answers
82 views
Trying to build a latch circuit on Qucs using BJT transistors. I can't find what is wrong
I seem to be able to get it to work on CircuitLab:
simulate this circuit – Schematic created using CircuitLab
However I can't, for the life of me, find a way to build the same thing on Qucs. I ...
4
votes
2answers
243 views
Qucs simulation of quarter wave microstrip stub doesn't match ideal calculaton
I'm trying to simulate the resonant frequency and insertion loss of a 3 mm open stub on a 10 mm microstrip transmission line (50 Ω) on a FR-4 PCB (εr = 4.0, height = 0.1 mm). I calculated that the ...
1
vote
1answer
145 views
RF amplifier biasing in QUCs
I have selected an infineon BFP840ESD BJT to work with in the design of a low noise RF amplifier. I'm trying to use Qucs Studio to simulate it.
From the datasheet I select my bias conditions with as ...
0
votes
1answer
26 views
Problem adding tranformer to QUCS schematic when simulating with ngspice
I'm having problems simulating the following circuit using ngspice alongside Qucs.
The main problem I can see in log is that is acusing an singular matrix.
I imagine the problem is related to how ...
1
vote
3answers
84 views
Different readings of voltmeter on simple circuit
Hi I am trying to learn the basics of electronics and puzzled by the following qucs simulation.
Why the readings of voltmeters are different? I would expect, by the way zero readings on both ...
0
votes
1answer
241 views
Common-Emitter NPN Transistor Amplifier Simulation Failed
I'm trying to simulate a simple common-emitter transistor amplifier presented as an example in Practical Electronics for Inventors in Qucs.
The circuity is identical to the one presented in the book. ...
0
votes
1answer
543 views
Simulation discrepancy in Qucs with 2N3904 transistor
I've been testing out a few circuit simulation applications and ran into an unusual issue with Qucs and the 2N3904 transistor. For a simple NPN transistor circuit with load resistor \$R_L\$, base ...
0
votes
0answers
79 views
NFC Antenna matching
I am trying to follow the TI document on NFC antenna matching for the TFR7970A chipset.
http://www.ti.com/lit/an/sloa241b/sloa241b.pdf
I am under linux, and while I could try wine to use the smith ...
0
votes
1answer
171 views
Resistance or conductance of resistor networks
I am trying to figure out if the equivalent resistance (or similarly conductance) of a resistor network can be calculated using Qucs (as opposed to solving the Kirchhoff equations directly, or doing ...
1
vote
1answer
37 views
Why is there no variation caused by this swept parameter?
I quite like Qucs now that I more or less have the hang of it. Unfortunately, I can't figure out how to get a parametric sweep working.
I'm running an AC simulation on this circuit:
For now I'm not ...
4
votes
1answer
722 views
Qucs model for 2.4 GHz matching circuit
I am designing a matching circuit for an EFR32BG13 SoC. The current board layout looks like this:
In addition to the visible layers (top and bottom), layer 2 is a solid ground plane and layer 3 is a ...
1
vote
1answer
398 views
Why is there no current flowing through the relay coil in this Qucs 0.0.19 simple dc circuit?
I just started looking at Qucs and am going through the components. I am puzzled by the results shown by the ammeters in the relay circuit below:
As you can see from the table, the circuit on the ...
1
vote
1answer
553 views
Matching wideband antenna with QUCS
I am trying to match a dipole antenna to a 50Ω source. Problem is that for my frequencies (VHF) the complex impedance basically circles the 50Ω point between VSWR 2 and 3 lines. Because of that ...
6
votes
1answer
2k views
Nonlinear equation solvers in SPICE simulators
We have an assignment at the Parallel processing class, the target is to implement a Non-linear Equations solver on cuda based on Newton Raphson method and to interface this solver with an application ...
1
vote
1answer
575 views
qucs capacitor simulation
I was playing with qucs and noticed that capacitors are not simulated as I expected. I designed simplest circuit that illustrates that case.
AC Source: 2 Hz (2 times a a second)
Capacitor: 1pF
...
0
votes
2answers
284 views
QUCS Darlington pair
I'm modeling a Darlington pair in QUCS to understand better how to use it in practice. The model is below:
The DC analysis predicts a current in the base of T1 of about 1uA and a collector current on ...
0
votes
2answers
429 views
QUCS simulation radio transistor amplifier
I'm trying to design a small amplifier for AM signals to use before the usual diode-C-R detection (the reception in my area is very poor). I devised a QUCS simulation as below:
The diode and ...
0
votes
1answer
637 views
How to setup a simulation on QUCS for a RF differential source?
I need to setup some simulations on QUCS for the RF circuit below:
Pin1 is IC's positive port and Pin2 is IC's negative port.
My initial goal is to investigate the circuit behavior on different ...
2
votes
1answer
756 views
Simulate capacitor discharge in Qucs
I want to find how long a capacitor takes to discharge from 12 volts to 2 volts using Qucs. I can use a voltmeter to measure the voltage across it when it charges up, but I cannot turn the power ...
2
votes
2answers
2k views
QUCS simulation of simple capacitor/resistor circuit - strange results.
Hi I have just started to learn electronics. In order to understand the RC constant I have built the following very simple circuit in QUCS simulator.
According to the formula
RC time constant = R ...
2
votes
1answer
2k views
Add a timer LM555C on Qucs
Does anyone know how to add a timer on Qucs ? The component's navigation bar doesn't help at all, It confuses me, I can't find a timer. I wondering, perhaps It could be added through library. In this ...
0
votes
1answer
516 views
Qucs How to add 10uF Polarised Capacitor
I'm new to this site. I have a small experiment. I did trying to make a circuit from a schema that needs 10uF Polarised Capacitor in the schema. I use Qucs (Quite Universal Circuit Simulator) qucs....
3
votes
1answer
2k views
Coupled Line Filter Design in Qucs
I'm getting to grips with designing coupled line filters and wanted to implement the band-pass filter described in Example 8.7, p. 435 in David Pozar's excellent "Microwave Engineering" just as a ...
6
votes
1answer
11k views
How do I import a spice model into QUCS
I am trying to import one of the spice models (from here) into QUCS.
I haven't been able to find much documentation about this except for vague hints that it is possible.
4
votes
1answer
4k views
How can I create a new component using Qucs?
I'm using Qucs for a simulation, but I don't understand how can I create a new component (E.g. a new LED from a data sheet). How can create it and use it easily in my project?
1
vote
1answer
1k views
How to model transistor ATF 53189 in QUCS?
In my internship I have to create an amplifier with low noise, high impedance and that works in the 100 to 400MHz band.
While searching for a transistor, I found the ATF 53189 (datasheet), which ...
4
votes
1answer
767 views
How do I measure the characteristics of a voltage divider in a QUCS simulation?
How do I measure the characteristics of a voltage divider in QUCS?
Below is what I have tried thus far, using Qucs 0.0.15 on Ubuntu 10.04
I want to measure how the voltage at the center of a ...
3
votes
2answers
1k views
Is there a way to open/import gschem .sch file in qucs?
Is there a way to open .sch files produced by gschem in qucs? The two applications use different file formats. Does anyone know if a converter exists?
5
votes
2answers
19k views
Qucs - what is DC sweep?
I'm learning how to use Qucs using the tutorial.
But I have no idea what is DC sweep, AC sweep, parameter sweep, Vsweep, ... and so why to even use them.
Could anyone please help explain what are ...
