Questions tagged [qucs]

Quite Universal Circuit Simulator (QUCS) is an open source analog and digital circuit simulator package.

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QucsStudio: Unknown variable

I'm using QucsStudio4.3.1 to simulate a voltage divider circuit. Everything is fine until I try to plot the result. The tutorial shown like below But the result I got is like Missing a properties ...
Jack Huang's user avatar
3 votes
4 answers
863 views

Why is this point giving me 8.3 V?

I am trying to find the voltage at V2 using the wire label in the Qucs-s simulator, powered by Ngspice. I have used Ohm’s law (V=IR) to work out the the voltage across R1 which was 1.66 volts;, but ...
Ekene Nwokedi's user avatar
1 vote
1 answer
121 views

Averaged first-order difference of Vout in QUCS

I am looking at a very simple LM317 voltage regulator circuit to drive a motor (represented by R3 in the diagram). I want to be able to sweep capacitor C2's capacitance and plot the mean 1st-order ...
TheDude's user avatar
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Microstrip directional coupler length = 90 degrees?

Desire to design a -30 db microstrip directional coupler using QUCS. Does the length of the coupled section of line need to be 90 degrees or will a shorter length of coupled line work? If I enter 45 ...
woffermom's user avatar
0 votes
1 answer
225 views

Qucs voltage divider tutorial: simulation error

I am going trough the voltage divider tutorial on pp. 4 and following of the Qucs manual. On p. 11, I simulate the circuit, and I obtain following message: What does this mean? I cannot insert a <...
Karlo's user avatar
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SX1272 bad performance

I want to use one shared antenna for the Lora/FSK transceiver sx1272 and LTE/GSM SIM700E module, with BGS12SN6 as a switch. I've matched the antenna with two conductor and validated the result with a ...
Wowa's user avatar
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1 vote
1 answer
138 views

Nonideal RF coupler model, admittance matrix in QUCS simulation

I'm trying to simulate a nonideal directional coupler in QUCS. Unfortunately, the only model available is the ideal one without taking into account the isolation or insertion loss values. Initially, I ...
UncannyValley's user avatar
1 vote
0 answers
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Using a non-time domain equation for a nonlinear equation based device in QUCS

I'm trying to model a magnetron oscillator source in QUCS. I am only interested in the output of the magnetron, not how it is powered. Traditionally a magnetron is modeled the same as many oscillators,...
kthaxt's user avatar
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3 answers
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How can I run a circuit with qucs?

I find this program, qucs, that looks very interesting. But it seems counterintuitive and I can't get it to work. I did this simple circuit But when I said to qucs to run it, it gave an unspecified ...
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2 votes
2 answers
4k 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 ...
gann's user avatar
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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 ...
Stefano Fedele's user avatar
2 votes
1 answer
982 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 ...
Stefano Fedele's user avatar
5 votes
2 answers
1k 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 ...
比尔盖子's user avatar
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1 vote
1 answer
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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 ...
Blargian's user avatar
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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 ...
Eduardo Amaral's user avatar
1 vote
3 answers
264 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 ...
Boris's user avatar
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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. ...
比尔盖子's user avatar
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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 ...
higrafey's user avatar
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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 ...
Nicolas Goy's user avatar
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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 ...
user929304's user avatar
1 vote
1 answer
75 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 ...
Reinderien's user avatar
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6 votes
1 answer
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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 ...
Michael Cooper's user avatar
1 vote
1 answer
599 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 ...
Jason210's user avatar
  • 113
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1 answer
959 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 ...
Jaanus's user avatar
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6 votes
1 answer
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 ...
Elbehery's user avatar
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1 answer
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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 ...
Max Fry's user avatar
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3 answers
395 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 ...
Luca's user avatar
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2 answers
558 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 ...
Luca's user avatar
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How to set up a simulation on QUCS for a RF differential source?

I need to set up some simulations on QUCS for the RF circuit below: Pin1 is the IC's positive port and Pin2 is the IC's negative port. My initial goal is to investigate the circuit behavior at ...
Cristiano's user avatar
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1 answer
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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 ...
Corey's user avatar
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2 votes
4 answers
3k 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 ...
Boris's user avatar
  • 177
2 votes
1 answer
3k 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 ...
Mike's user avatar
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0 votes
1 answer
732 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....
Mike's user avatar
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3 votes
1 answer
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 ...
electroGeek's user avatar
6 votes
1 answer
16k 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.
user2557313's user avatar
4 votes
1 answer
5k 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?
G M's user avatar
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1 vote
1 answer
2k 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 ...
eng.M.AHMED's user avatar
4 votes
1 answer
961 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 ...
JonnyRo's user avatar
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3 votes
2 answers
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?
fukanchik's user avatar
  • 143
6 votes
2 answers
21k 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 ...
Toussaint's user avatar