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Re: Trouble with some devices
Or you can model it as a length of transmission line. Below a quarter-wavelength long, it will behave as an inductance, exactly like the real wire does. The thing I don't see specified on the schematic, is the proximity between the wire and the ground plane. The amount of inductance depends not on its length but on the loop area enclosed by the wire and its return path (ground plane), so you would get totally different results for a PCB trace as opposed to a wire suspended above the circuit board. Andy |
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Re: Trouble with some devices
Hello,
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Every component has a two or more leads. Even if you make it as short as possible, you will always have more than 1nH on every lead. Also one shouldn't forget the capacitance of every device to the ground plane if there is one. Best regards, Helmut --- In LTspice@..., "christianvierck" <christianvierck@...> wrote:
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Re: Trouble with some devices
Thank you for the advice. I will try this first and find out, how to manage the seperate inductions afterwards.
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--- In LTspice@..., John Woodgate <jmw@...> wrote:
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Re: Trouble with some devices
@Helmut: I'm not sure how to allocate the inductions to the seperate pins. But I will find out how to manage it.
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@andy:If I change the details on the bb105 diode it does not change the frequency at the antenna. I have splitted the coil into two parts and calculated the induction of both parts separate. When I increase the induction of the coil with two rounds the frequeny decreases. I will test the silver wire as a inductor now. Thank you. --- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:
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Re: Trouble with some devices
John Woodgate
In message <kt5rjr+q9qr@...>, dated Mon, 29 Jul 2013, Helmut <helmutsennewald@...> writes:
Be aware that all the components have inductance of 0.5nH to 1nH per mm of wire length.Specifically, that silver wire is an *inductor* and needs to be modelled as such. You can find formulas for the inductance of a wire of specified dimensions on the Internet. -- OOO - Own Opinions Only. With best wishes. 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 |
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Re: Trouble with some devices
I think the frequency is determined by the first stage, with the BB105 and
the 25 mm long wire. The coil L is in the second stage which is an RF amplifier and shouldn't change the frequency (or am I mistaken?). The silver or silvered wire is puzzling. I guess the precise 25 mm length is to make an inductor, and the designer must have thought that it needs very low RF (skin effect) resistance, to get large Q. You would not see that effect unless you include skin effect resistance in your simulation. Andy |
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Re: Trouble with some devices
Thank you.
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I used the BFR92 as the BFR92 already. My problem is the BB105 which is not available anymore. The point with the silvered copper seems reasonable. I searched the ECM in english and the third contact makes sense. I searched german webpages before and nothing made sense before. --- In LTspice@..., "miller_effect" <miller_effect@...> wrote:
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Re: Trouble with some devices
Hello Christian,
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You forgot the many x*nH inductance of every component-pin. Best regards, Helmut --- In LTspice@..., "christianvierck" <christianvierck@...> wrote:
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Re: Trouble with some devices
Thank you.
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The model is a good approach for the original device. As I mentioned before, I used a V-source as the ECM and connected the output with the negative cable. I also think that silver wire and copper wire are equal. Now I simulated it(AC) and my frequency at the antenna is a good deal bigger than 900MHz. Probably I made a mistake calculating the inductances of the coil. I will repeat it now. --- In LTspice@..., "Helmut" <helmutsennewald@...> wrote:
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Re: Trouble with some devices
Hello CV,
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Original reference uses BFR92 which is plenty good enough for this gadget. Per result of 45 sec search, look in Philips catalogs: (copy entire line sans line breaks) Regarding silver: they likely mean silvered copper to reduce skin effect losses (improve conductance of the wire surface layer, a common treatment of high-power transmitter hardware). Regarding microphone: search for electret microphone. You will see it is a capacitor driving a JFET. ME --- In LTspice@..., "christianvierck" <christianvierck@...> wrote:
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Re: Trouble with some devices
Hello Christian,
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When I assume C1=18pF and C30=2pF, a reasonable diode model could be as shown below. .model BB105 D(Is=.1p Rs=1 Bv=35 Ibv=10u Cjo=35p Vj=.75 M=.8) Use Cjo and M to adjust the capacitance. The ECM is a V-source with 1kOhm or 2kOhm output resistance. I think using silver wire or copper wire doesn't matter. You can try to calculate the resistance taking skin effect into account. Be aware that all the components have inductance of 0.5nH to 1nH per mm of wire length. Best regards, Helmut --- In LTspice@..., "christianvierck" <christianvierck@...> wrote:
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Re: Trouble with some devices
John Woodgate
In message <kt5gi5+d3ua@...>, dated Mon, 29 Jul 2013, christianvierck <christianvierck@...> writes:
I need some help to simulate my circuit correctly.I'm not sure we should help you with an illegal transmitter, especially as it can be used to invade privacy. -- OOO - Own Opinions Only. With best wishes. 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 |
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Trouble with some devices
Hey guys,
I need some help to simulate my circuit correctly. I want to simulate a UHF-transmitter and I have problems with three devices in my curcuit. Here you can see the circuit diagram: Now the three devices which exasperate me. 1. BB105: I did not find any model for this device. I'm not sure if it's manufacturing stoped. Can someone help me with this? A alternative model or sth. 2. ECM: Like other microphones I used a voltage source in my simulation. Now I'm not sure how to connect it with my curcuit? 3. Silver wire: Can I leave it for a simulation because of the same conductance as a copper wire? Have a nice day, CV |
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Re: Simulation conditions to check Starter circuit.
John Woodgate
In message <kt59nb+uf0v@...>, dated Mon, 29 Jul 2013, shukichi2079 <shukichi2079@...> writes:
This is Shukichi.This is not enough information for us to be able to help you. Please post your schematic AND all model and subcircuit files need to run it to Files => Temp on the list's web site, as a zip archive. -- OOO - Own Opinions Only. With best wishes. 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 |
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Simulation conditions to check Starter circuit.
Hello.
This is Shukichi. I want to check Starter circuit that move correctly or not. Circuit is power supply with starter. I think it is checked by transient simulation, and tried some conditons. but it didn't move correctly. There were no difference between circuit with starter and without starter. please teach it. Regards. Shukichi |
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Re: abcd for cable modeling
John Woodgate
In message <CALBs-Ti+aoOcfQycr1TTkGEM_rctOP6+uArGyOTTS=YT=xJhsA@...>, dated Sun, 28 Jul 2013, Andy <Andrew.Ingraham@...> writes:
If instead all you have is a physical description of the lines and topologies, then SPICE's standard transmission line element might be the best choice.One significant effect in PLC is mode conversion; the signal is launched differentially but mode conversion to common-mode occurs at discontinuities in the cables, such as Y-junctions, switches etc. The cables have three conductors and should be treated as 3-wire transmission lines (which is written-up in the literature). So a 3-wire 'cell', used with LTspice's 'array' feature is more appropriate than the standard transmission line. -- OOO - Own Opinions Only. With best wishes. 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 |
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Re: How to resize individual components
I'm connecting diodes to relays and the diode symbol is almost as large as the entire relay symbol. The appearance of the combination and how the connections are made is very awkward looking.
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--- In LTspice@..., Andy <Andrew.Ingraham@...> wrote:
What sort of "resize" are you referring to? |
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FFT ratios V / I = Z ? (was CSV to PWL)
Given a plot of a pink or white noise voltage, and a synchronized plot of the current induced in a partially reactive load -
Will the 'normalized' ratio of the FFT plots be an indication of Z? I'm looking at the low frequency end of the FFT, to avoid sampling issues. By normalized, I mean that 1 volt would produce 1 amp with both plots resolving to 0dB at the minimum sampled frequency (the load being partially inductive in this example). It seems much too simple...... RL |
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Re: How to resize individual components
What sort of "resize" are you referring to? If you want to resize the schematic symbols, the size of each symbol is fixed. You would have to create new symbols with different sizes. LTspice includes a symbol editor. Andy |
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