Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- LTspice
- Messages
Search
|
Re: MPS4250
jean_claudeabeille wrote:
I uploaded the new corrected one along with the missing components files : AmpJCA.zip.Still has errors. Still missing the LF353. LTspice is looking for the schematic symbol (.asy file). Needs a statement to include the special "standard.bjt" file. Meanwhile I received 2 models of mps4250. Simulations with one of them and with BC557 Probably both ... or neither. Remember all components have tolerances, which for some transistor parameters can be on the order of +/-100% or so (well, +100%, -50%, or more). In fact results are very dependent of model's parameters. That's unfortunate. A good amplifier design ought to make the results largely independent of model parameters, over a reasonable range. Besides, I don't know if it's important but on my amp, U2 is CNY17-4 whichAs long as you include a model for the CNY17-4, it's OK. What I woud like to understand is HOW to equilibrate the voltages at theHere's where the discussion becomes off-topic for this forum, because we are now talking about amplifier design, rather than circuit simulation. One would use the trimmer 1K resistor to set the quiescent (static) currents through R101 and R111. To get equal currents through R101 and R111, that should happen automatically. As long as no current goes out to the load, all the current through R101 flows through R111. To get no quiescent current to the load, trim the input offset voltage so that the output pin sits at 0V when the input is 0V. Regards, Andy |
|
Re: MPS4250
jean_claudeabeille
thank you Helmut for your patience and answers. Now, it's more clear in my mind.
toggle quoted message
Show quoted text
Besides, some answers didn't satisfy me : R4 and especially D4 and R12. How does my amp can work since it is in this configuration ? If I figure it out well, electronics can only be understood by practicing but certainly not by reading books like I do. Silly of me. --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
|
|
Re: MPS4250
Macy wrote:
.model PN4250 PNP(Is=6.734f Xti=3 Eg=1.11 Vaf=45.7 Bf=388.2 Ne=1.806 ... hmmm...don't need the parentheses anymore eh?Parentheses were never needed there. Unless I am mistaken, they are treated like whitespace. This goes back to the 1970s (Berkeley SPICE). There are some places where parentheses are mandatory, but a .MODEL statement is not one of them. They are harmless, so it can be useful to add them, to show that the entire enclosed text is a list of parameters. Andy |
|
Re: LTspice World Tour in Australia
John Woodgate
In message <kshfhj+al36@...>, dated Sun, 21 Jul 2013, Helmut <helmutsennewald@...> writes:
I want only remind that Mike is on tour in Australia this week.That will compensate them for losing the first two cricket Test Matches, but not 100%. (;-) -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
|
Re: MPS4250
Hello Jean,
My answers are below. --- In LTspice@..., "jean_claudeabeille" <jean_claudeabeille@...> wrote: R4 has to be ideally connected to the output as I did. Then the offset of the amplifier output will be only the offset of U1B. If we connect R4to the net "C5", the offset of U1B will be multiplied by the gain 25 of the amplifier. - D5 instead of Q5I don't have the model parameters for a Vbe breakdown. You also don't know what breakdown voltage you get. 7v, 8V, 9V? - D4 added1.5V of one LED is too less. - Q11 PNP instead of NPNYou had a NPN symbol but named it a PNP. That's a "foul play". :-) The simulation will simply not work as intended. I replaced it with a PNP to leave the PNP-type. Alternatively one could had rename the NPN with a NPN-type. - U1A output connected to I-I have shown the only correct usage of unused opamps. To make this even more save, connect a 10k resistor between GND and the +input of U1A. (I had forgot this resistor.) This is not the real schematic, the one I uploaded.You should look that the opamp output U1B is not at the rails. If this is the case and your circuit is correctly wired, you should try a slightly larger or lower value of R5 to bring the opamp output into its linear region. At very low frequency of a few Hz, this loop will cancel your AC audio signal. It will behave like having a highpass with a few Hz in the input. How do you worked to get this solution ? What is the trick ?I have 35 years experience with analog circuit design. At last, what is the job of D3/D107,It limits the input differential voltage during power-up and down or if somebody connects an AC-coupled pre-amplifier or the input voltage is faster than the amplifier can follow.. D102/D103.They avoid that you expensive amplifier will be destroyed due to reverse bias during power-up and down. I apologize wasting your time with so basic questions,You had made a mix of a few schematic drawing mistakes and a very few design errors. The combination makes it hard to get the first working simulation. Now it's working. PS: I like the idea with Q14. It limits the maximum current of Q8. Best regards, Helmut |
|
Re: LTspice Genealogy - The Heritage of Simulation Ubiquity
Simulation Program with Integrated Circuit Emphasis -----Original Message-----
From: LTspice@... [mailto:LTspice@...] On Behalf Of Henry McCall Sent: Saturday, July 20, 2013 1:27 PM To: LTspice@... Subject: Re: [LTspice] Re: LTspice Genealogy - The Heritage of Simulation Ubiquity The grandfather of all spice programs was a phd thesis in one of the California universities. it was even called spice which indicated a ( S? Program for Integrated Circuit Engineering.) it's primary purpose was mos circuits as I recall. It was mid to late 60's I think. On 7/20/2013 1:16 PM, John Woodgate wrote: In message <kseg1d+mptm@...>, dated Sat, 20 Jul 2013, ------------------------------------ Yahoo! Groups Links |
|
Re: MPS4250
jean_claudeabeille
OK. I agree, on your schematic, the amp works fine. Problem is : why did you changed, added components and changed some wires :
toggle quoted message
Show quoted text
- output on R4 in place of C5 - D5 instead of Q5 - D4 added - Q11 PNP instead of NPN - U1A output connected to I- - deleted R12. This is not the real schematic, the one I uploaded. What does mean : "Watch this voltage. Select R5!" ? I understand nothing about this :" This control loop has to be slower then the lower corner frequency of your amplifier". Can you develop this ? How do you worked to get this solution ? What is the trick ? At last, what is the job of D3/D107, D102/D103. I apologize wasting your time with so basic questions, but I try to understand. I read the first part of B. Cordell's book and learn a lot but not enough to understand this damn amp. I asked some help to B. Cordell but he answered to read chapaers 1-4. Am I stupid or something ? --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
|
|
Re: MPS4250
jean_claudeabeille
OK, thank you
toggle quoted message
Show quoted text
--- In LTspice@..., John Woodgate <jmw@...> wrote:
|
|
Re: MPS4250
Hello Jean,
toggle quoted message
Show quoted text
I have uploaded a new version which tries to use most of your original values while still has all the necessary corrections. Please continue with this version in your project. Files > Temp > AmpJCA_1b.zip The LF353 regulates the DC-output voltage to the DC-input voltage. Therefore the opamp adjusts the current of the JFets which changes the voltage drop on R5. Basically it equalize the collector current of Q8 and Q12. This control loop has to be slower then the lower corner frequency of your amplifier. Best regards, Helmut --- In LTspice@..., "jean_claudeabeille" <jean_claudeabeille@...> wrote:
|
|
Re: MPS4250
John Woodgate
In message <ksg876+8t42@...>, dated Sun, 21 Jul 2013, jean_claudeabeille <jean_claudeabeille@...> writes:
What I woud like to understand is HOW to equilibrate the voltages at the collectors of Q12 and Q13 to get quite the same current at R101 and R111.I suggest you follow Helmut's advice, because your question is about amplifier design, not LTspice simulation. -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
|
Re: MPS4250
jean_claudeabeille
OK, Helmut, if "we don't want discuss the design of audio amplifiers", I give up !
toggle quoted message
Show quoted text
--- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
|
|
Re: MPS4250
jean_claudeabeille
Hello John
toggle quoted message
Show quoted text
You are right, there are some errors in the schematic. I uploaded the new corrected one along with the missing components files : AmpJCA.zip. I hope that this time the schematic is correct. Meanwhile I received 2 models of mps4250. Simulations with one of them and with BC557 give very different results. Which one is true ? LTSpice's one - BC557B or BC557C - I guess. In fact results are very dependent of model's parameters. Besides, I don't know if it's important but on my amp, U2 is CNY17-4 which is not present in LTSpice's OPTOS. What I woud like to understand is HOW to equilibrate the voltages at the collectors of Q12 and Q13 to get quite the same current at R101 and R111. --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
|
|
Re: MPS4250
found this old thing ...similar, somebody may want it.
toggle quoted message
Show quoted text
.model PN4250 PNP(Is=6.734f Xti=3 Eg=1.11 Vaf=45.7 Bf=388.2 Ne=1.806 + Ise=6.734f Ikf=.205 Xtb=1.5 Br=2.635 Nc=2 Isc=0 Ikr=0 Rc=1.67 + Cjc=6.2p Mjc=.301 Vjc=.75 Fc=.5 Cje=7.5p Mje=.2861 Vje=.75 + Tr=9.861n Tf=467.9p Itf=.17 Vtf=5 Xtf=8 Rb=10) * National pid=62 case=TO92 * 88-09-08 bam creation hmmm...don't need the parentheses anymore eh? --- jean_claudeabeille@... wrote: From: "jean_claudeabeille" <jean_claudeabeille@...> To: LTspice@... Subject: [LTspice] Re: MPS4250 Date: Sun, 21 Jul 2013 00:01:32 -0000 Thank you for your answer, it's very kind --- In LTspice@..., ¨¢???????? ?????????¡Á <BordodunovAlex@...> wrote:
|
|
Re: MPS4250
jean_claudeabeille
Thank you for your answer, it's very kind
toggle quoted message
Show quoted text
--- In LTspice@..., ¨¢???????? ?????????¡Á <BordodunovAlex@...> wrote:
|
|
Re: LTspice Genealogy - The Heritage of Simulation Ubiquity
The grandfather of all spice programs was a phd thesis in one of the California universities.
toggle quoted message
Show quoted text
it was even called spice which indicated a ( S? Program for Integrated Circuit Engineering.) it's primary purpose was mos circuits as I recall. It was mid to late 60's I think. On 7/20/2013 1:16 PM, John Woodgate wrote:
In message <kseg1d+mptm@...>, dated Sat, 20 Jul 2013, |
|
Re: MPS4250
--- In LTspice@..., abeill?? jean-claude <jean_claudeabeille@...> wrote:
Hello Jean, The circuit had a lot of mistakes. I tried to correct them. Please watch all the circles and my other comments in the schematic. My files: Files > Temp > AmpJCA_1.zip I have used most of the missing transistor models from bordodynov's file standard.zip. Over all we don't want discuss the design of audio amplifiers in the LTspice Yahoo group. You should do that in DiY-Audio groups. There are also books about audio amplifiers, e.g. this one from Cordell, . Best regards, Helmut |
|
Re: LTspice Genealogy - The Heritage of Simulation Ubiquity
John Woodgate
In message <kseg1d+mptm@...>, dated Sat, 20 Jul 2013, legg@... writes:
Mind you, there are spice era files from (likely) elsewhere that predate these - mostly libraries. The same file type from a Basso Pspice CD install is marked Nov98.It's normally completely impossible to know when anything really started. I know that an ex-colleague was doing simulations at Kings College, London of audio circuits using FORTRAN with matrices no later than early 1964 (because that's when the lab caught fire). -- OOO - Own Opinions Only. See www.jmwa.demon.co.uk Why is the stapler always empty just when you want it? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK |
Dick Benson
to navigate to use esc to dismiss