> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of Djula Djarmati
> Sent: 14 March 2012 17:22
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]:: "Interesting" LED flasher circuit
>=20
> On 14-Mar-12 17:35, RussellMc wrote:
> >> I tried to simulate this in LTSpice over lunch;
> >
> > Lonnnnng lunch :-)
> >
> >> nothing I have tried so far will make the circuit oscillate reliably i=
n
> its original form, including make the capacitors significantly different
> values, adding some leakage, changing the collector resistors etc.  I get
> some chaotic behaviour at power on, but not really what you'd expect from
> an LED flasher.  Moving the base resistors up the Vcc immediately creates
> a perfectly operating astable.
> >
> >> That's obviously not to say it couldn't work in practice, but I very
> much doubt it will be reliable or repeatable between different builds.  I
> wonder how many people have thrown their soldering irons away in disgust
> after wasting hours with this?
> >
> > The sample of one user that I am aware of who has built it says it
> > works well. Much to my chagrin :-).
> >
> >
> >      Russell
> >
>=20
> It works in LTSpice too. It is a bad design but it does work.
>=20
> Djula

Yep it works for me now after syncing the LTSpice release (it was quite old=
....).  The collector resistors or base resistors must be different to make =
it start (or using two different transistors works).  Making the two capaci=
tor values different (even x2) does not make it start if the other componen=
ts are equal however.  The period is also about doubled compared to having =
the base resistors in the correct location.

Mike

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.