The first flip-flop

[Geordie McBoyne]

Came across this website this evening: https://spectrum.ieee.org/geek-life/hand...t-flipflop

The bistable flip-flop[ is over 100 years old. Attributed to W. Eccles and F.W. Jordan.

Geordie McBoyne.

[ppppenguin]

I knew it had been invented by Eccles and Jordan but didn't realise it was so early. Sometimes the inventor of a circuit isn't so clear. There are things invented by Blumlein that have other people's names attached to them.

[Diabolical Artificer]

Why the odd resistor values? 115.3k 92.9 & 91.8k in the grids?

Andy.

[peter scott]

Why the odd resistor values? 115.3k 92.9 & 91.8k in the grids?

Andy.

Perhaps to guarantee some minor offset at start-up??

Peter

[ppppenguin]

It says that they carefully tweaked the resistor values to make it work.

[BusyBee]

I have never built a valve flip flop. It always seemed a bit of a waste as transistor circuits are so easy and cheap but maybe worthwhile for a change. At one time I had some of those cards from an old electronic learning kit which had transistor flip flops but sadly I think they have gone. A valve version would be different and I have a good number of cheap subminiature pentodes. Still perhaps really a waste.

My only point about the resistors is - If they are critical how long would the circuit work for with the vaguaries of resistors in those days. I wonder if it is just that they were those found to work, and their actual values were measured, rather than defining values in a range as today. More of a laboratory experiment with elaboration of working conditions.

It does look early except that the batteries spoil it a bit. Personally I would have put the batteries elsewhere. Maybe underneath. I suspect many here could improve on that. I wouldn't claim to be able to do any better though, and it is inspiring. Duracell are losing it on not picking up on advertising potential lol

Tracy

[ppppenguin]

The emitter coupled mulitvibrator is supposed to be more reliable than the classic cross-coupled Eccles-Jordan. I can't immediately find a valve version.

[reset]

Why the odd resistor values? 115.3k 92.9 & 91.8k in the grids?

Andy.

Perhaps to guarantee some minor offset at start-up??

Peter 

Yes sir. When power is applied you want a predetermined condition.

[Doodlebug]

I wonder if there are many at Bletchley Park?

[Kalee20]

Suprised he had trouble making it work. I made one using an ECC82 double triode some years ago, a few minutes of tweaking and it was in business!

I didn't realise Eccles and Jordan were doing this stuff as long ago as that, wow!!