Explaining the design process on the example of a wobulator

You did that as a student. Wow. I tip my hat to your ability! :grin:

Scope - yes, wobulator - no.
It was so needed for me that I had no choice.

An year befor scope I have made an chronocomparator. Not sure of English name - the device you put electronic watch on its small table and it shows you its offset with resolution ±0.1s/day (I’ve got absolute accuracy probably about ± 0.5s/day). It was the beginning of electronic watches time (at least here in Poland) and people imported the chippest once. Many of them just haven’t the trimmer in them. Then they went to service to do something as their watch has offset more then a minute per day. My known service-man had a problem how to regulate it after inserting the trimmer. He asked customers to come, and come, and come - day after day, made some changes, noted and so on. He showed me (not his) professional such device (I could’t open it as it was sealed (at guarantee)) and we agreed that I will do something like that. I’ve got for it 2,5 times my fathers month salary.
When I told him how hard it was for me to do it haveing no scope he offered me one old, broken down tube scope. I used its housing, main tube and trafo and build the rest (with transistors and some TTL ICs) myself.

I am certain that even your teacher and fellow students were amazed at what you could do. I had never heard of a wobulator.

Wobulator gives you 2 signals - one (about 20…50Hz) saw-like to drive scope X-axis and second is the higher frequency with f changing like that saw signal. When you drive with that output the amplifier input you can see at scope the amplifier characteristic. The picture I send you was the amplifier with demodulator at output. If not demodulated what you see is X-axis symmetrical.
Many years ago I have heared from someone the sentence: Day without wobulation is the lost day :slight_smile:

No my teacher knew that I have done it. I was at the last year and we had much more theoretic electronic. Scope was only my private hobby. I have written an article about it and (November 82) send to electronic magazine. About March 83 I got letter that it was accepted and after only one year :slight_smile: it was published.
But later my students know it, as I gaved them as linear circuit excercises the task to design the scope Y amplifier. They of course used my schematic (some of them tried to design something different) but they had to understand what for is each element and from what its value comes. The amplifier construction is very symmetrical and you have to reach relatively high voltage. Tube needed about 40V per cm so the final stage of amplifier was powered from +175V.

I tried to find the like that Y amplifier just to show what I am speaking about and I found my article :slight_smile: :
At page 6 the Rys.2 and Rys 3 are the Y-amplifier schematic.
In my opinion to understand its construction is a very good electronic lesson (may be some electronic beginners read this).
At Rys 8. there is a bug. There should be a dot connecting output of G with input of H.
At Rys 9. from right is the Z-axis input - it is also interested how I moved low voltage signal to -1000V level preserving its DC part.

No sir. This is not for beginners. Even more than the oscilloscope, I tried to picture your description of how you made pcb’s in the early 80’s using things like liquid shoe polish, syringes and ink pen cartridges. I’m looking at your schematics and I see logic gates. This was done in 1982. This is genius level stuff.
Piotr (Galka) one of the letters are not in the English alphabet.
I’m having a dialogue with one of the top electronic engineers in the world!

It was not my idea. I just read somewhere how to do it. I think I made my first PCB that way about 1973. I had a 20cm wooden line with two wooden toy blocks fixed at its ends to have that line about 1 cm over PCB to help to paint straight tracks. When building my scope I had that PCB technology well controlled.

If TTLs were accessible for me in Poland (those time communistic country) than they have to be well known in normal world. I have a 700 pages book about TTLs printed in 1980. I’ve read it whole just after I bought it.
Using TTLs in 1982 was not genius. The genius was what Rejewski had done breaking Enigma in 1932.

I hate when you are doing something like that! It is not the first time. Could you just stop.
May be it (my scope) is high level for electronic technician (someone after electronic secondary school) but certainly not for electronic engineer (someone after electronic study).

It was not shoe polish. It was shoe paint.
I heared first time about shoe paint when I read how to home-make PCBs. The author wrote that he tested many paints and it seems for him the best (not dry too fast). I have never meet anyone who painted shoes.

Lesson learned.
I kick myself because I majored in philosophy. Much later in life when I found out I could change the behavior of a machine by writing instructions for it I was hooked. I knew I had wasted my college years.

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