Simple rail-to-rail astable multivibrator

[E-design]

Most people know the normal two transistor astable-multivibrator circuits with caps between opposite base and collector. Most text books cover them. There is also another form of this using a capacitor coupled-emitter configuration. This is rarely seen in text books. Below is an extract from the book "Pulse and Digital Circuits" with some timing equations.

If you add an output stage and a variable pot, you can get a nice rail-to-rail output square wave with some duty cycle adjustment.

 

[d123]

Hi,

That's nice, thanks for sharing it.

 

[E-design]

The basic idea seems to come out of the Fairchild Semiconductor stable in an application note 59 named "An Improved Emitter-coupled Multivibrator" from 1963.

I could not find a copy of this note, just references made to it.