Re: Oscillators in LTspice

On Fri, 18 Oct 2024 10:08:15 -0700, john larkin <jl@glen--canyon.com>
wrote:

On Fri, 18 Oct 2024 16:33:22 -0000 (UTC), Cursitor Doom
<cd999666@notformail.com> wrote:
>

Gentlemen,
>
I've never spiced an oscillator AFAICR. Do they self-start in spice
simulators (LT in particular)? IOW, did Mike Engleheart build something
into the engine which generates wideband 'background' noise, particularly
at 'power up' as it were? I'm assuming there must be some such mechanism
and if there is, it must be present by default for all schematics one
attempts to simulate and not just oscillators?

>
Oscillators in LT Spice often need to be goosed with an injected pulse
or some initial condition setting, if they are to start in a tolerable
time, or at all.
>
Or skip the initial conditions solution, or bring up the power
supplies after sim start.
>
In a multivibrator, some tiny component value tweak can make the
asymmetry to kick things off.
>
Actually, the classic astable mv usually has a genuine hangup state,
both transistors saturated.

The supply coming up should be enough of a goose to start the
oscillator.

boB