Double word maths anomaly

[John Drew]

Hi Charlie, I moved the topic into Proton24 so it doesn't show as an anomaly request. I think you were using a 16bit PIC, if not I'll move it again.

By the way I was using the A/D to measure a voltage for a telemetry project and I'd put a zener across the voltage divider's output as a precaution and found the same issue. I just removed it as I have a crowbar elsewhere. Useful for me to remember what the graph of a zener diode looks like!

It's warming up down here, 33C on Friday.
Merry Christmas to you and the whole gang on the forum.
John

[charliecoutas]

Hi John

Thanks for moving the post.

I'm slightly embarrassed that after 50+ years messing about with electronics, I always thought that a zener was effectively open circuit until you reached its rated voltage. I'm also discovering that you can run certain op-amps at very low voltages.

33C! Here in the south of the UK it's cold and damp and foggy and most people are very nervous about the new virus strain.

So very best wishes for Christmas and the new year to you, Maxeen and everybody on this wonderful forum.

Charlie

[top204]

Have you tried blowing the coating off the Cathode Charlie? My dad had an old, second hand, valve tester/rejuvinator when I was a boy, so it was very, very old. LOL He would put a valve into it and it would test it, then blow the Cathode with a high voltage, low current, to clean it, and test it again. It would then place an induction over the valve to see if there was anything left in the getter and absorb whatever it could. I know it worked because I used to use it for the valve televisions I used to get given as a boy so I could experiment with them, or me and dad used to remove the components for our component shelves in the garden shed (the hut as we used to call it). :-)

Wonderful times, with a wonderful man. My dad and my best friend all rolled into one, and sadly missed for 38 years now. :-( He was only 52 when he had an unexpected massive heart attack 11 days before Christmas, and he passed away in my arms. I was told by the medic that came, that my efforts to revive him would not have worked because it was a blocked artery. :-( He actually made a point of coming back to the house a few days later to tell me, because he could see the state I was in, and I did not want to leave loose of my lovely dad for them. :-(

[shantanu@india]

Touching eulogy Les.
Dad's always leave some part of themselves with their son. My Dad was a mechanical engineer from the old school who had spent his entire career in the steel industry. I grew up near a steel plant with the chimneys at the horizon as my constant companion. My Dad used to talk about coke ovens, blast furnaces to his starry eyed kid. He was my first physics teacher and gave me the first concepts of mechanics.Somewhere, deep inside me I always knew that I was destined to make machines.

[charliecoutas]

Your Dad sounds like he was a wonderful man, Les. I was inspired at about seven years old by the old man across the road from our house in Grimsby, Mr Greenwood. He spent many hours in his garden shed which was full of electronic gear. This was in 1953. He made me a crystal set in a lovely polished wooden box. I spent many hours listening to the one of two stations it could receive. He taught me about volts, amps and ohms. This gave me that desire to find out how things worked. I'm still at it!

Dismantling a brand new wrist watch in hospital at the age of ten, with suspected appendicitis, taught me that a watch mainspring has enough stored energy to spray all the other inpatients with the remaining contents of the watch.

I'll run your ideas about valve restoration past Ken, our valve man at Bletchley, and let you know. Sounds feasible.

Charlie

[top204]

So you're a Lincolnshire lad Charlie? Do you have the north humber accent?

We are looking at houses in the south Lincoln area as well, i.e. Spalding, Holbeach etc... They are only 15 miles from where we lived near Wisbech, and we often drove to Spalding or Boston for the day.

I used to get wrong off Dad for dismantling his things so I could see how they worked, then never got to put them back together. LOL So I fully understand the fascination with mechanical things, as you do.

My dad told me a lovely story about when he was a boy in the early 1940s, and was repairing a wind up gramophone he had been given, that had a snapped spring. He was winding up the spring for tests, but forgot to fasten it in properly and it flew out and hit him in the chest! They were huge powerful springs! His words to me were "It knocked me over the chair and I was lying on the floor and I couldn't bloody breath. The bruise on my chest was huge". :-) But he stil fixed it and used it in his bedroom. :-) It's marvelous what you remember from childhood, but I was always a curious kid and asked mum and dad many, many, many questions about "everything". LOL

[charliecoutas]

I lost my Humberside accent when I moved the Loughborough aged 16. I went on an apprenticeship to learn about electronic engineering, computers, girls and how to drink. I succeeded in most of those things.

It turns out that we have a clock-spring expert at Bletchley. I watched him replace the spring in a cuckoo clock; the precautions he took showed great respect the energy that is stored in a spring. There is also quite a lot of energy stored in a 100uF electrolytic when charged to 300 volts. The lads in the electronic maintenance dept where I worked in Loughborough would sometimes throw one to unsuspecting student apprentices. That's probably why I don't catch most things that are casually tossed to me.

If John (Drew) wants to move this thread somewhere else, then I, and probably Les, would understand.

Best wishes
Charlie 

[John Drew]

I don't think so Charlie, it's just wonderful to read two friends sharing. It's one of the reasons this forum is what it is - a friendly, respectful, helpful space.
Merry Christmas to all from John (down under)

[top204]

Your dad seems like a lovely man Shantanu. Hopefully, he is still with us.

I'm sure, wherever he is, he is proud of his little boy and glad he shared his knowledge and enjoyment with him.

You are so right John. We have lovely people on this forum, and I look forward to meeting some of them when I, eventually, move down south again (home)... But not too far south, because I'm not a southerner! LOL. My Rachel is, she's a lovely Kentish lass. :-) The only problem is that since my head injury, I cannot travel too far and certainly cannot drive too far because I also suffer from fatique, but I'm sure we can meet up somewhere around Lincolnshire/Norfolk, or their will always be a spare bedroom for a night. :-)

[top204]

There is also quite a lot of energy stored in a 100uF electrolytic when charged to 300 volts

You are absolutely right Charlie. We often used to charge mains capacitors in the workshop and place them on various work benches, so when they were picked up to move out of the way... "Ouch!!!!!!  Which of you B*#t#rds did that?". LOL, but we were all guilty of it with each other, and after a time, we forgot it could happen, or weren't taking much notice, so we fell for it again and again over the years, to roars of laughter from the rest. :-)

The older electrolytic capacitors used to be filled with tar, and did not have weak spots in their casings, so when they went bang, they "really" went bang and made a mess. :-) I've had a few of them go off when I was a young-un in the shed and working on the very old TV sets I used to get given. I wish I had kept them, because old, useless, rubbish then is now worth thousands of pounds, for some incomprehensible reason!

I used to work in a television factory repairing the sets that failed on the line, and one day, they received a bunch of TV boards that had the mains electrolytic capacitors (68uF/350V) fitted backwards. The boards used to be fitted in their cases, then placed on the top conveyor belt, powered up, and moved around the factory for various tests and additions. All of a sudden, there was a tremendous bang, bang, bang, bang happening on the top conveyor belt and smoke belching out everywhere, because the capacitors started to explode, and there was an awful lot of TVs on the line. :-) It's just as well they exploded on the top conveyor instead of in front of the tester girls, because they often had their hands inside the TVs for tweaks etc...