Instead of using cursors, we can use .meas() (measure) directive to get the values of interest. See video tutorial here: th-cam.com/video/hBiO85JQ0OE/w-d-xo.html
Note: For latest versions of LTSPICE, the model definition file that you need to edit can be found in the location C:\Users\[USERNAME]\Documents\LTspiceXVII\lib\cmp and NOT the folder where LTSPICE is installed (such as C:\Program Files\LTC\LTspiceXVII\lib\cmp).
That's all very well but how do you do an AC analysis on this to get, say, the output impedance of whole circuit for different current draws? You need the mains voltage to be continually cycling (to provide the power) while you draw the current at various frequencies. One can do that in real life, but can we do it in simulation?
Thank you for the feedback and suggestion. It might be possible to do this via an AC sweep over the input. However, I have not seen any technical details related to this in any textbook. You would need to provide more details.
@@electriccircuits7164 The problem is having a voltage source that just runs at 50Hz and 230V into the main transformer and then having a current source (as a load) which does an AC sweep. The first requires a .tran and the seond needs a .ac command. Even if we make it simpler than an output impedance, how would we get the frequency response of the system? (That actually may be more complicated. LOL.) What I need is the mains/transformer cycling away and topping up the reservoir capacitors while doing an AC sweep on the rest of the circuit. Obviously I need somewhere I can draw power from, and that's usually the reservoir capacitors.
In case I've not made it clear, what I would do on the bench is a) switch on the power supply. Then, b), I would drive a small resistive load through a power transistor or perhaps a Darlington so we have a constant current sink. the base of that transistor would be swept across the frequency band, especially at LF where the impedance of the capacitors is high, and I would look to see what the voltage on the V+ rail is to determine the output Z of the supply.
LTSPICE has a few 30V, 1W zener diode models already defined. You can also add this model to LTSPICE for a 30V, 5W zener (D1N5363B). This has I_ZM = 158mA from its datasheet. .model D1N5363B D(IS=1.65E-10 RS=7.38 TT=5.01E-8 CJO=1.73E-10 M=0.33 BV=29.7 IBV=0.0416 type=zener) This can be a starting point. Good luck with your project.
There is a small typo in the video. In the "how to simulate a transformer" section, following the convention with which the transformer turns ratio n is defined (4:52) then v_sec = n * v_pri not v_sec = (1/n) * v_pri The values shown and simulated in the video are all correct since they use the v_sec = n * v_pri relationship.
This can be easily done by writing a small script in any programming language. See for instance the Matlab script below: % Inputs f = 50; Vpri_rms = 240; R = 1e3; C = 100e-6; % Transformer turns ratio n = 1/20; Lsec = 1; Lpri = (1/n)^2 % Voltages Vsec_p = (n)*(Vpri_rms)*sqrt(2) Vo_p = Vsec_p - 1.4 Vr_pp = Vo_p/(2*f*R*C) Vo_DC = Vo_p - 0.5*Vr_pp Note that power supply circuits typically do not have such a high frequency input signal.
Thank you. Can you please elaborate what you mean. Do you mean a single regulated power supply circuit that can produce 3 DC output voltages such as 5V, 10V, 15V?
@@electriccircuits7164 Yes, something like this; Suppose a power supply is needed to supply the following three outputs: Fixed positive 6V Varying positive 25V Varying negative 20V Construct and simulate the required power supply circuit using LTspice VIII, explain the function of each stage and also show the output of each stage.
Sir i want to know that if i want output of 4.7V contant so what value of capacitor should i choose input is 110 60hz R=1k By that formula i am not getting correct waveform
The formula to determine the smoothing capacitor is given in the video. This formula is derived under certain conditions which assume near ideal operation. It is the zener regulator that will ensure 4.7V constant output.
Hello, The procedure to add zener diodes is described in the video. 1N759 is a 12V zener. Its model can be defined as: .model D1N759 D(Is=1.773f Rs=2.06 Ikf=0 N=1 Xti=3 Eg=1.11 Cjo=102p M=.4868 Vj=.75 Fc=.5 Isr=1.393n Nr=2 Bv=12 Ibv=79.489m Nbv=1.1528 Ibvl=142.9n Nbvl=.95108 Tbv1=700u) BZX84C12L is also a 12V Zener in LTSPice.
You need to have admin access to your computer. Note: For latest versions of LTSPICE, the model definition file that you need to edit can be found in the location C:\Users\[USERNAME]\Documents\LTspiceXVII\lib\cmp and NOT the folder where LTSPICE is installed (such as C:\Program Files\LTC\LTspiceXVII\lib\cmp).
Thank you for the excellent question. We are just interested in getting the desired turns ratio right. Hence, we can pick the inductance values accordingly to give the desired turns ratio. Practical inductors have values that typically range from 1 µH to tens of H. 400 H value is outside that range. It is also possible to pick inductor values that are within the practical range and satisfy the desired turns ratio criteria.
This is a design choice and there is no unique correct answer. If you want 20V DC, you would select the Zener part name first to provide that voltage...there are a few 20V Zener Diode models available in LTSPICE. The Zener diode stage must have an input voltage (smoothed DC voltage) greater than 20V. What exact value you set is within your control. This then enables design of two resistors for Zener diode stage, taking zener diode parameters V_Z, I_ZK, I_ZM into account. Also you can work backwards to work out what is the peak value of transformer secondary voltage you need. From that you work out a turns ratio. You can round off values of turns ratio to adjust your design. Then simulate to confirm your design. The relevant theory is discussed in this video and the video on Zener diodes in this channel. Good luck with the project!
sorry for the disturbance sir,I am an ec student from MYSURU NIE college.I am designing an audio amplifier in LTspice to amplify sound from headjack of mobile using voltage amplifier and push pull amplifier but not able to drive speaker because of less amplification of voltage .if you have time to help me please send me your mail id,so that i can send my design draft and get help from you .
Instead of using cursors, we can use .meas() (measure) directive to get the values of interest. See video tutorial here: th-cam.com/video/hBiO85JQ0OE/w-d-xo.html
Thx u save my life i spend a whole night to study how to create that your video make it complete
Great you were able to advance your learning by watching the video!
Straight forward video, learned a lot about how to use LTspice aswell
Thank you for the feedback!
Note: For latest versions of LTSPICE, the model definition file that you need to edit can be found in the location C:\Users\[USERNAME]\Documents\LTspiceXVII\lib\cmp and NOT the folder where LTSPICE is installed (such as C:\Program Files\LTC\LTspiceXVII\lib\cmp).
This was very helpful. Can you please do a circuit with three outputs.
Thanks bro , i have a project and i chosed the regulated power supply .
Glad its helped your learning!
That's all very well but how do you do an AC analysis on this to get, say, the output impedance of whole circuit for different current draws? You need the mains voltage to be continually cycling (to provide the power) while you draw the current at various frequencies. One can do that in real life, but can we do it in simulation?
Thank you for the feedback and suggestion. It might be possible to do this via an AC sweep over the input. However, I have not seen any technical details related to this in any textbook. You would need to provide more details.
@@electriccircuits7164 The problem is having a voltage source that just runs at 50Hz and 230V into the main transformer and then having a current source (as a load) which does an AC sweep. The first requires a .tran and the seond needs a .ac command. Even if we make it simpler than an output impedance, how would we get the frequency response of the system? (That actually may be more complicated. LOL.) What I need is the mains/transformer cycling away and topping up the reservoir capacitors while doing an AC sweep on the rest of the circuit. Obviously I need somewhere I can draw power from, and that's usually the reservoir capacitors.
In case I've not made it clear, what I would do on the bench is a) switch on the power supply. Then, b), I would drive a small resistive load through a power transistor or perhaps a Darlington so we have a constant current sink. the base of that transistor would be swept across the frequency band, especially at LF where the impedance of the capacitors is high, and I would look to see what the voltage on the V+ rail is to determine the output Z of the supply.
If i have to make a 3A-30v regulated power supply , what should i replace in the circuit?
I appreciate your help...
LTSPICE has a few 30V, 1W zener diode models already defined.
You can also add this model to LTSPICE for a 30V, 5W zener (D1N5363B). This has I_ZM = 158mA from its datasheet.
.model D1N5363B D(IS=1.65E-10 RS=7.38 TT=5.01E-8 CJO=1.73E-10 M=0.33 BV=29.7 IBV=0.0416 type=zener)
This can be a starting point. Good luck with your project.
There is a small typo in the video. In the "how to simulate a transformer" section, following the convention with which the transformer turns ratio n is defined (4:52) then
v_sec = n * v_pri
not v_sec = (1/n) * v_pri
The values shown and simulated in the video are all correct since they use the v_sec = n * v_pri relationship.
could you do the calculations for 120V rms at 1KHz Please?
This can be easily done by writing a small script in any programming language. See for instance the Matlab script below:
% Inputs
f = 50;
Vpri_rms = 240;
R = 1e3;
C = 100e-6;
% Transformer turns ratio
n = 1/20;
Lsec = 1;
Lpri = (1/n)^2
% Voltages
Vsec_p = (n)*(Vpri_rms)*sqrt(2)
Vo_p = Vsec_p - 1.4
Vr_pp = Vo_p/(2*f*R*C)
Vo_DC = Vo_p - 0.5*Vr_pp
Note that power supply circuits typically do not have such a high frequency input signal.
If we want to find capacitance which resistance should we use the shunt resistance that is attached to zener regulator or the load resistance?
Excellent question! It would be the thevenin equivalent resistance seen by the capacitor (for the zener regulator stage).
How do we make the output 24V?
You have to decide a suitable 24V Zener and then design the circuit appropriately.
This was very helpful. Can you please do a circuit with three outputs.
Thank you. Can you please elaborate what you mean. Do you mean a single regulated power supply circuit that can produce 3 DC output voltages such as 5V, 10V, 15V?
@@electriccircuits7164
Yes, something like this;
Suppose a power supply is needed to supply the following three outputs:
Fixed positive 6V
Varying positive 25V
Varying negative 20V
Construct and simulate the required power supply circuit using LTspice VIII, explain the
function of each stage and also show the output of each stage.
Sir i want to know that if i want output of 4.7V contant so what value of capacitor should i choose input is 110 60hz R=1k
By that formula i am not getting correct waveform
The formula to determine the smoothing capacitor is given in the video. This formula is derived under certain conditions which assume near ideal operation. It is the zener regulator that will ensure 4.7V constant output.
Can we get 12v output using the same circuit
Yes. Transformer secondary output may need modification accordingly.
Sir I am not able to add diodes
It's showing access to C:\program Files\LTC\LTspice\lib\cmp\standard. dio was denied
@@electriccircuits7164 sir I cannot find 7812 zener
Hello, The procedure to add zener diodes is described in the video. 1N759 is a 12V zener. Its model can be defined as:
.model D1N759 D(Is=1.773f Rs=2.06 Ikf=0 N=1 Xti=3 Eg=1.11 Cjo=102p M=.4868 Vj=.75 Fc=.5 Isr=1.393n Nr=2 Bv=12 Ibv=79.489m Nbv=1.1528 Ibvl=142.9n Nbvl=.95108 Tbv1=700u)
BZX84C12L is also a 12V Zener in LTSPice.
You need to have admin access to your computer.
Note: For latest versions of LTSPICE, the model definition file that you need to edit can be found in the location C:\Users\[USERNAME]\Documents\LTspiceXVII\lib\cmp and NOT the folder where LTSPICE is installed (such as C:\Program Files\LTC\LTspiceXVII\lib\cmp).
the vid was very helpful, can u please attach the asc file
You will maximise your learning if you create the file yourself. All the information you need is in the video.
can i know how did u get primary inductance to be 400 ??
Thank you for the excellent question. We are just interested in getting the desired turns ratio right. Hence, we can pick the inductance values accordingly to give the desired turns ratio. Practical inductors have values that typically range from 1 µH to tens of H. 400 H value is outside that range. It is also possible to pick inductor values that are within the practical range and satisfy the desired turns ratio criteria.
My project is converting 240 AC to 20 V dc
So whats the ratio that i need to use and component value of the circuit that needed to be changed
This is a design choice and there is no unique correct answer. If you want 20V DC, you would select the Zener part name first to provide that voltage...there are a few 20V Zener Diode models available in LTSPICE. The Zener diode stage must have an input voltage (smoothed DC voltage) greater than 20V. What exact value you set is within your control. This then enables design of two resistors for Zener diode stage, taking zener diode parameters V_Z, I_ZK, I_ZM into account. Also you can work backwards to work out what is the peak value of transformer secondary voltage you need. From that you work out a turns ratio. You can round off values of turns ratio to adjust your design. Then simulate to confirm your design. The relevant theory is discussed in this video and the video on Zener diodes in this channel. Good luck with the project!
Make series regulator too
Thank you for the topic suggestion.
sorry for the disturbance sir,I am an ec student from MYSURU NIE college.I am designing an audio amplifier in LTspice to amplify sound from headjack of mobile using voltage amplifier and push pull amplifier but not able to drive speaker because of less amplification of voltage .if you have time to help me please send me your mail id,so that i can send my design draft and get help from you .
Thank you. Best wishes for your project.