In article , F-Red
wrote:

PS I know there are lots of methods of doing this from ic555 ic4011 or even
two transistor oscillators, but that's not KISS enough for me.

Standard building block bistable circuit will do what you want. Two
transistors, two capacitors and four? resistors.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Andy Luckman (AJL Electronics) wrote:

In article , F-Red
wrote:

PS I know there are lots of methods of doing this from ic555 ic4011 or even
two transistor oscillators, but that's not KISS enough for me.


Standard building block bistable circuit will do what you want. Two
transistors, two capacitors and four? resistors.


Hoew about a unijunction with the LED in its collector?

In article ,
The Natural Philosopher writes:

Hoew about a unijunction with the LED in its collector?

It would be hard (maybe impossible) to get the on-off ratio
50%. Also, the with the output being saw-tooth rather than
square wave in a conventional unijunction oscillator, the
LED would fade off each time. BTW, there's no 'collector'
in a unijunction transistor -- I presume you mean the drain?
(I think it's about 30 years since I last used a UJT, and
that was to generate a timebase for an oscilloscope I was
building from an old telly;-)

--
Andrew Gabriel

PS I know there are lots of methods of doing this from ic555
ic4011 or even
two transistor oscillators, but that's not KISS enough for me.

I've just come across this which appears to do what you want,
although the flash rate might be a bit quick?

http://www.wireless-alarms.net/Dual_...ght-p-235.html

"Andrew Gabriel" wrote in message
...
In article ,
The Natural Philosopher writes:

Hoew about a unijunction with the LED in its collector?

It would be hard (maybe impossible) to get the on-off ratio
50%. Also, the with the output being saw-tooth rather than
square wave in a conventional unijunction oscillator, the
LED would fade off each time. BTW, there's no 'collector'
in a unijunction transistor -- I presume you mean the drain?
(I think it's about 30 years since I last used a UJT,

And that was probably 5-10 years after they stopped making them :-)

In article ,
"Mike" writes:

"Andrew Gabriel" wrote in message
...
In article ,
The Natural Philosopher writes:

Hoew about a unijunction with the LED in its collector?

It would be hard (maybe impossible) to get the on-off ratio
50%. Also, the with the output being saw-tooth rather than
square wave in a conventional unijunction oscillator, the
LED would fade off each time. BTW, there's no 'collector'
in a unijunction transistor -- I presume you mean the drain?
(I think it's about 30 years since I last used a UJT,

And that was probably 5-10 years after they stopped making them :-)

Oh have they? How sad.
....and I still remember the part number I used - 2N2646

--
Andrew Gabriel

"Andrew Gabriel" wrote in message
...

...and I still remember the part number I used - 2N2646


A quick search on this number reveals two companies still make them - Comset
and BOCA. Never heard of either but at $2 a piece there's obviously enough
profit in it for some garage semicon plant to churn them out :-)

In article , Andrew Gabriel wrote:

And that was probably 5-10 years after they stopped making them :-)

Oh have they? How sad.
...and I still remember the part number I used - 2N2646

Ah, the metal TO-18 version.
How many would you like? RS still stock them and they are sold
individually

G.

--
http://busker.org | http://www.clustervision.com

(Andrew Gabriel)

In article ,
The Natural Philosopher writes:

Hoew about a unijunction with the LED in its collector?

It would be hard (maybe impossible) to get the on-off ratio
50%. Also, the with the output being saw-tooth rather than
square wave in a conventional unijunction oscillator, the
LED would fade off each time. BTW, there's no 'collector'
in a unijunction transistor -- I presume you mean the drain?

Just to be pedantic its E,B1,B2 on a UJT,Its an electronic switch, no gain
so no collector or drain :-)
It would work, but to be effective would need anther transistor, which
would make the component count as high as an ordinary flip/flop.

--
F-Red

Mike wrote:

"Andrew Gabriel" wrote in message
...

In article ,
The Natural Philosopher writes:

Hoew about a unijunction with the LED in its collector?

It would be hard (maybe impossible) to get the on-off ratio
50%. Also, the with the output being saw-tooth rather than
square wave in a conventional unijunction oscillator, the
LED would fade off each time. BTW, there's no 'collector'
in a unijunction transistor -- I presume you mean the drain?
(I think it's about 30 years since I last used a UJT,


And that was probably 5-10 years after they stopped making them :-)


I thought that a very short pulse every few seconds was what was required.

Don't use teh gate, use the (drain? No that's a FET surely...)

F-Red wrote:

(Andrew Gabriel)


In article ,
The Natural Philosopher writes:

Hoew about a unijunction with the LED in its collector?

It would be hard (maybe impossible) to get the on-off ratio
50%. Also, the with the output being saw-tooth rather than
square wave in a conventional unijunction oscillator, the
LED would fade off each time. BTW, there's no 'collector'
in a unijunction transistor -- I presume you mean the drain?


Just to be pedantic its E,B1,B2 on a UJT,Its an electronic switch, no gain
so no collector or drain :-)
It would work, but to be effective would need anther transistor, which
would make the component count as high as an ordinary flip/flop.


I thought that the anode went into heavy conduction durng the pulse
discharge phase.