General purpose scaler from PE 1965.

[Techman]

I saved this home-made scaler from going in a skip a year or so back. It was built from an article featured in Practical Electronics of October 1965 and I knew the chap who originally built it. It's not the best of builds, but still worked when powered up after years in storage.

I thought I would share this with members and wondered if any other examples of this scaler have been known to have been built, and if they have, are there any other survivors? I think the chances are very remote.

The last picture shows it counting the radioactive pulses from the dial of my late fathers old wrist watch

[Techman]

A few more pictures:-

[KeithsTV]

I remember that article. I only had part 2 until recently, as the November issue was the first PE I bought. I have both parts of the article if you want a copy. We had something similar at school used not only for measuring radiation but also as a general purpose counter.

Having written a few articles for various magazines I often wondered how many people built the various projects. I know a few examples of the electronic ignition system and the Nicam decoder I had published were built as I had feedback via the magazine. I think if 100 people built the project you were doing well.

Keith

[Techman]

I can imagine what it must be like having spent a lot of time putting together an article for a magazine and wondering whether many people will actually build the item. The scaler shown has very limited use and I would guess that you could count on one hand any that were built, although I could be very wrong. It's very 'component heavy' and there's a lot of construction involved in the chassis and case.

As for a copy of the original article - would you believe, I have 'part 1', but not 'part 2', the opposite to you. I have a very tatty copy of the October 1965 Practical Electronics magazine with the front cover completely missing and the first page torn away. I only knew that it was an October 65 copy due to a mention on one of the inside pages of what was going to be in the next months issue in November. I believe that the copy I have is the actual copy used by the constructor of this scaler. He would have had the November copy with 'part 2' in as well, but this has now been lost many years ago. I think the 'part 1' has survived because there would have been the need for reference for a bit of fault finding and 'de-bugging' following construction.

Keith, thank you for your very kind offer. I would very much appreciate a copy of 'part 2' of the article, or if you have a combined 'part 1 & 2' copy then that would be fine, whatever is convenient for you. Many thanks.

[Dekatron]

There are actually three parts to this article, the third part discusses the use and has some examples.

I have all three parts as a scanned document, pm me if you want a copy via email - it is some 11MB large.

/Martin

[dseymo1]

We also had similar counters at school - they seem to have been quite common at tge time.

Rather like cookery books, I suspect that many read the magazines for entertainment, some for education, and a few specifically to construct the projects. Having said that, while I remember only having made a couple of items as published, I have on a number of occasions adopted and adapted the principles of published circuits, and suspect that this is / was a common approach.

[KeithsTV]

Here's the two constructional articles and the follow up article on using it. I've also added the front cover of the October issue.

Keith

[Techman]

I had no idea there was a third part to this article. Many thanks to Martin for the offer of the scans and also to Keith for posting them on the thread. Martins scans are probably higher resolution than can be posted on the forum, but I have saved Keiths scans and they are good enough to print out and I was pleased to see the original front cover which was missing on my part one copy. It completes the information on this unit by having the entire article on the thread to be viewed by everyone.

It was interesting to read through the two following parts of the article, particularly the description of ‘Finding “g”. the acceleration of gravity’ in the third part, I’d never seen that article before, well, not that I can remember. Back in the 70s (when I first remember seeing this scaler being used) the person that built it asked me if I could make him that particular piece of kit. I don’t remember seeing a picture or description, he may have drawn me a sketch, I can’t remember. He gave me an electromagnet and one very large ball bearing and one smaller one and I built the entire thing from scratch. I didn’t use the method shown with the PO switch, I designed it with a trap door arrangement which instantly broke the contact when the ball hit it. I arranged the construction of it so that it would contain the ball on a soft pad inside, and made it so that the ball could be quickly retrieved for re-setting on the electromagnet to take another reading, rather than it bouncing off (as it looks like it does as shown in the article) and flying off across the room never to be seen again. The only design fault that showed up during the forty odd years of future use was that with excessive battering with the large ball when dropped from its highest point, the trap door that I had made from aluminium got a bit bent out of shape. This was easily straightened and was still being used with a more modern, ready built counter (similar to, but older than the one shown in the first picture below, which is mid 80s), certainly up to a couple of years ago, infact I only ever remember it being used with the more modern 70s scaler – shame I don’t have a photo of it.

The builder of the scaler described in the article and shown in the first two posts on this thread was a teacher (dseymo1 said in post #6 that he’d seen these sort of things in school) and was a prolific builder of electronic kits from various articles in these publications. The second picture below shows another bit of kit I very much believe he was responsible for, it’s a radiation detector with the detector in an old pen case and the cream knob looks very familiar to the ones used on the scaler – I’m sure someone will be able to say what PE publication this was in.

[KeithsTV]

There was another 3 part article starting in the February 66 issue on a solid state portable ratemeter using either a GM tube or a solid state detector which seems to be similar to the earlier scaler. Can scan it if anyone is interested.

Keith

[Techman]

Yes please, Keith. That sounds familiar. I wonder whether I may have come across that one, too.

[KeithsTV]

Here's the series with a few of my markings on the Feb issue.

Keith

[Techman]

Many thanks for that, Keith. That does look very familiar. I think I've seen that article before somewhere. I have quite a few old PEs (obviously not the ones you posted before), but I may have one (or more) of the ones you've just posted - I'll have to check out the loft pile!

I used to have a stack of those counter/scaler units with the Dekatron tubes as used in the homebrew scaler shown. They were the large rack mounted type units made by such as Ekco and I think Dynatron. There was the Ekco scaler with the two rows of Dekatron tubes and the square push buttons. Then there were the older type which had the blocks of flashing neons and the mechanical counters, also ratemeters, DC amps, large EHT units, the workmanship and build quality of these was fantastic. It was all ex Harwell stuff. I made a big rack unit out of Dexion to keep them all in. Unfortunately, I let the whole lot go for scrap in the late 90s, they were taking up a huge amount of space in my workshop. I feel really bad about letting them all go now and really don't like to even think about it. There is one small survivor from that time which is an old Airmec 1021B radiation monitor which has never been opened up or powered up in my living memory - so one day, soon, maybe!

[KeithsTV]

The later article mentions another article on the semiconductor sensor. I'll dig that out and post it as it may add something to the 66 unit.

As I said we had a similar counter timer with dekatrons at school and at one point we set it up as a reaction timer testing everyone in the class. It was not unusual for us to try to devise alternate uses and experiments for a lot of the equipment while the teacher was out of the room. I would guess most of that went for scrap years ago although at NVCF this year I did see an old Unilab scope kit.

Keith

[julie_m]

We had a similar device in my secondary school physics lab.

Measuring g was done by configuring it as a timer, using an electromagnet connected to the "STOP" contacts to suspend a steel ball-bearing one metre above an improvised switch connected to the "START" contacts which would open on impact, and then disconnecting the electromagnet.

I got 9.1 rather than the accepted 9.8, probably due to the time taken for the magnetic field to collapse before the ball-bearing fell and the time taken for the bottom contact to open.

[KeithsTV]

And to complete the series of articles here's one on the solid state radiation detector written by the same author as the Feb 66 article.

Keith

[Techman]

Thank you for posting that last scan, Keith, it's possible that got built as well. Thanks also to others that have provided interesting input to this thread. Looking at that portable ratemeter scan, I could be just dreaming it, (well, it is a very long time ago) but I'm sure I remember seeing that built sometime around 1970. I seem to remember it was painted with blue mottled Hammerite, but I don't think it was ever used due to it not being completely finished or it not ever working properly. I don't remember what happened to it in the end, but it probably got broken up for parts.