I want to build an LO

I associate motional with motion, like a quartz resonator.

Everybody else was talking about oscillators until you and JT got nasty. That seems to be the pattern.

What a buffoon you are! Do you think the lurkers on this group cannot read? Do you think they believe such nonsensical statements from you? You're mentally ill, man. Ask your wife. ...Jim Thompson

--- Up until I joined the thread, the only ones in it were Hamed, Andrew Holme - who helped - and you, who chose to proselytize.

Just three people, so it was hardly the crowd you imply was there.

Speaking of patterns, one I've seen you employ almost exclusively, and that Jim has commented on, is that you very rarely supply quantitative help; preferring to issue qualitative edicts from your lofty throne while demeaning your critics.

What I posted was:

"I think Hamed is asking for a VFO schematic to get him started, not for show-off grandstanding.

Can you help him, or not?"

A little harsh for constructive criticism, perhaps, but hardly nasty.

-- JF

The mentally-ill Larkin keeps spouting that "Everybody else was talking about oscillators until you and JT got nasty", when just the opposite is the case...

I posted 10 links to schematics (with values, natch :-)

The mentally-ill Larkin needs to seek treatment... now!

What a moroon buffoon >:-} ...Jim Thompson

Radiotron Designer's Handbook calls it "Resonant Impedance".

I was talking about oscillators, 3rd post in this thread. Then you started up with stupid insults about "grandstanding."

Your standard seems to be that any on-topic help is "grandstanding." Well, by those standards, you sure aren't guilty.

John S reasonably asked about JT's hidden Spice equation, and JT responded by calling him stupid.

What's wrong with you two? You continually pollute technical discussions with pointless insults.

That's what I'd call it. I just chose the method so that I could easily keep control of amplitude while I varied frequency and Q. ...Jim Thompson

I gave Hamed some useful advice and references. You call that proselytizing. Bizarre.

Off topic, useless, and as usual, turning a technical discussion personal.

Say something about LC oscillators. Post a working oscillator, with values. Set an example for us all.

Or keep whining.

Quite so. Sometimes just called "The Dynamic".

In the case of a parallel circuit, with loss resistance only in the inductor, and Q high enough to neglect the effect of R on resonant frequency, it reduces to:

Zd = L/CR

Radiotron Designer's handbook gives a more thorough treatment in terms of admittance, including capacitance losses, and resistive effects on resonant frequency.

What it all boils down to is: keep the L/C ratio as high as possible.

I threw this simulation together to illustrate the effects of varying L/C ratio. 1MHz resonant frequency, constant Q, and the ratio L/C varied from

There is a plot file after the .asc file, which plots Zd.

Version 4 SHEET 1 880 680 WIRE 144 80 -16 80 WIRE 256 80 144 80 WIRE 144 128 144 80 WIRE 256 128 256 80 WIRE -16 160 -16 80 WIRE 256 224 256 208 WIRE -16 336 -16 240 WIRE 144 336 144 192 WIRE 144 336 -16 336 WIRE 192 336 144 336 WIRE 256 336 256 304 WIRE 256 336 192 336 FLAG 144 336 0 FLAG 192 336 0 SYMBOL ind 240 112 R0 SYMATTR InstName L1 SYMATTR Value {1u*sqrt(N)} SYMBOL cap 128 128 R0 SYMATTR InstName C1 SYMATTR Value {25.33n/sqrt(N)} SYMBOL res 240 208 R0 WINDOW 3 36 52 Left 2 SYMATTR InstName R1 SYMATTR Value {w*1u*sqrt(N)/Q} SYMBOL voltage -16 144 R0 WINDOW 123 24 108 Left 2 WINDOW 39 24 120 Left 2 SYMATTR InstName V1 SYMATTR Value "" SYMATTR Value2 AC 1 SYMATTR SpiceLine Rser=1000 TEXT 336 56 Left 2 !.param w=2*pi*1e6 TEXT 336 136 Left 2 !.ac dec 1000 300k 1.8meg TEXT 336 88 Left 2 !.step param N 0.1 10 1 TEXT 336 112 Left 2 !.plot V(n001) TEXT 336 72 Left 2 !.param Q=100

No, it doesn't. Sorry.

This one does:

--- I have, often, in the past, so the example has already been set.

You, however, seem unwilling to follow it and, instead, post to be in the limelight while doing as little actual work as possible.

---

--- PKB???

-- JF

It's a very old joke. I first heard it in 1969 as "amplifiers you design oscillate and oscillators don't".

Obviously. But at least they oscillate.

never

Consider your vocabulary expanded.

?;-)

you,

nasty. That

So you wish to characterize this as really helpful??

So, I should refer to all impedances as "dynamic motional impedances"? Like you do?

I did another spin of the circuit I posted, using a current source, instead of a voltage, so as to remove external damping. This demonstrates that the bandwidth doesn't change with L/C ratio, only the resonant impedance. Rd now swings from about 800 to 2500 ohms, for a swing in L/C of

Plot file after the .asc file.

Version 4 SHEET 1 880 680 WIRE 144 80 -16 80 WIRE 256 80 144 80 WIRE 144 128 144 80 WIRE 256 128 256 80 WIRE -16 160 -16 80 WIRE 256 224 256 208 WIRE -16 336 -16 240 WIRE 144 336 144 192 WIRE 144 336 -16 336 WIRE 256 336 256 304 WIRE 256 336 144 336 WIRE 144 368 144 336 FLAG 144 368 0 SYMBOL ind 240 112 R0 SYMATTR InstName L1 SYMATTR Value {1u*sqrt(N)} SYMATTR SpiceLine Rser=0 SYMBOL cap 128 128 R0 SYMATTR InstName C1 SYMATTR Value {25.33n/sqrt(N)} SYMBOL res 240 208 R0 WINDOW 3 36 52 Left 2 SYMATTR Value {(w*1u*sqrt(N))/Q} SYMATTR InstName R1 SYMBOL current -16 160 R0 WINDOW 123 24 92 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I1 SYMATTR Value "" SYMATTR Value2 AC 1 TEXT 336 56 Left 2 !.param w=2*pi*1e6 TEXT 336 136 Left 2 !.ac lin 1000 300k 1.8meg TEXT 336 88 Left 2 !.step param N 10 100 10 TEXT 336 112 Left 2 !.plot V(n001) TEXT 336 72 Left 2 !.param Q=40 TEXT -24 384 Left 2 !.measure tmp max mag(V(n001))\n.measure BW trig mag(V(n001))=tmp/sqrt(2) rise=1 targ mag(V(n001))=tmp/sqrt(2) fall=last

Plot file: