Size reduction in a few decades - UK Vintage Radio Repair and Restoration Discussion Forum

peter_scott · 3rd Dec 2007, 5:28 pm

Back in the late '60s I pulled this PCB out of a skip as a source of components but as time has passed it has become much more interesting as a complete assembly.

The title in the top right reads "Transistor Counter Decade" and the board measures 32 cm x 18 cm.

What dramatic items of technology change do you have stashed away?

Peter

Al (astral highway) · 3rd Dec 2007, 5:51 pm

Sorry to hijack your post, Peter, but I couldn't commenting on the title.

I would present a very good example of size increase in a few decades!

BTW, what is the circuit that have posted? Is it an early multiplexer?

peter_scott · 3rd Dec 2007, 7:55 pm

Hi Al,

The whole board constitutes one single decade counter!

Peter

Tim · 3rd Dec 2007, 9:10 pm

Ah, but what size would it have been, had it used valves!

Al (astral highway) · 3rd Dec 2007, 9:13 pm

Unbelievable component count!! But stangely beautiful, to my warped mind.

Al (astral highway) · 3rd Dec 2007, 9:14 pm

Ah, but imagine what size it would have been, had it been electro-mechanical!

GMB · 3rd Dec 2007, 11:54 pm

Quote:

Ah, but what size would it have been, had it used valves!

Ah, but imagine what size it would have been, had it been electro-mechanical!

Well I think you will find the surprising answer to both of these is "quite a bit smaller".

The valve version of that board is a single decatron tube.
The mechanical version is perhaps a counter.
I have a unit with decatrons and mechanical counters and the whole lot is smaller than that board.

I don't think there was much attempt to make that board small - they were shooting for fast and reliable and fitting in a standard card frame.

Al (astral highway) · 4th Dec 2007, 1:55 am

That's interesting. I know nothing about decatrons or decade counting (or division, for that matter

). When you say 'they were shooting for fast and reliable', that intrigues me.

Perhaps like the OP, I thought it was a rather compact layout at first glance, but that was based on a completely foundationless assumption that this was a low-frequency counter where things like stray inductance weren't critical.

What sort of frequency would this have been running at?

Do you have a circuit diagram for this kind of thing? I'm starting to ask myself about the loading of the previous stages by the successive stage.

RobinBirch · 4th Dec 2007, 1:41 pm

Interestingly I used to have a couple of 19 inch racks full of Racal decade counters. Each decade counter was a valve circuit with a stack of double triodes (ECC82s) and a 0 to 9 bulb readout.

One module was the PSU and you could add more and more of the counter racks to get to the number that you wanted.

Each decade was a removable module plugged into a back plane and each module was a LOT bigger than the board presented.

Sadly when I got it it was just a source of spares and so I broke it up for the valves, sockets and mechanical bits and bobs.

Robin

peter_scott · 4th Dec 2007, 4:01 pm

Quote:

Originally Posted by astral highway

What sort of frequency would this have been running at?

Do you have a circuit diagram for this kind of thing?

Hi Al,

I don't think it's a BCD counter. I think it's a rather inefficient arrangement
of ten of the attached flip-flop. I suspect it's a fairly low frequency counter.
Certainly less than 10MHz.

Peter

3rd Dec 2007, 5:28 pm	#1
peter_scott Dekatron Join Date: May 2003 Location: Edinburgh, UK. Posts: 3,274	Size reduction in a few decades Back in the late '60s I pulled this PCB out of a skip as a source of components but as time has passed it has become much more interesting as a complete assembly. The title in the top right reads "Transistor Counter Decade" and the board measures 32 cm x 18 cm. What dramatic items of technology change do you have stashed away? Peter Attached Thumbnails

3rd Dec 2007, 5:51 pm	#2
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Re: Size reduction in a few decades Sorry to hijack your post, Peter, but I couldn't commenting on the title. I would present a very good example of size increase in a few decades! BTW, what is the circuit that have posted? Is it an early multiplexer? __________________ Al

3rd Dec 2007, 7:55 pm	#3
peter_scott Dekatron Join Date: May 2003 Location: Edinburgh, UK. Posts: 3,274	Re: Size reduction in a few decades Hi Al, The whole board constitutes one single decade counter! Peter

3rd Dec 2007, 9:10 pm	#4
Tim Dekatron Join Date: Jan 2003 Location: Bradford on Avon, Wiltshire, UK. Posts: 3,310	Re: Size reduction in a few decades Ah, but what size would it have been, had it used valves! __________________ "Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."

3rd Dec 2007, 9:13 pm	#5
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Re: Size reduction in a few decades Unbelievable component count!! But stangely beautiful, to my warped mind. __________________ Al

3rd Dec 2007, 9:14 pm	#6
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Re: Size reduction in a few decades Ah, but imagine what size it would have been, had it been electro-mechanical! __________________ Al

4th Dec 2007, 1:55 am	#8
Al (astral highway) Dekatron Join Date: Nov 2006 Location: London, UK. Posts: 3,496	Re: Size reduction in a few decades That's interesting. I know nothing about decatrons or decade counting (or division, for that matter). When you say 'they were shooting for fast and reliable', that intrigues me. Perhaps like the OP, I thought it was a rather compact layout at first glance, but that was based on a completely foundationless assumption that this was a low-frequency counter where things like stray inductance weren't critical. What sort of frequency would this have been running at? Do you have a circuit diagram for this kind of thing? I'm starting to ask myself about the loading of the previous stages by the successive stage. __________________ Al

4th Dec 2007, 1:41 pm	#9
RobinBirch Hexode Join Date: Apr 2003 Location: Cotswolds, UK. Posts: 465	Re: Size reduction in a few decades Interestingly I used to have a couple of 19 inch racks full of Racal decade counters. Each decade counter was a valve circuit with a stack of double triodes (ECC82s) and a 0 to 9 bulb readout. One module was the PSU and you could add more and more of the counter racks to get to the number that you wanted. Each decade was a removable module plugged into a back plane and each module was a LOT bigger than the board presented. Sadly when I got it it was just a source of spares and so I broke it up for the valves, sockets and mechanical bits and bobs. Robin