some early inspiration

[Opcom]

I'm putting up a mass of bookshelves and have finally started to unseal the many boxes of books here including some beginner volumes from my youth.

Sadly, some valuable interdisciplinary knowledge such as the home-making of a selenium photocell as described in "The Boy Electrician" is no longer offered in today's childrens' books. The many projects in a stack of books like this were a good place to start learning the arts of  'making'.

"Buy a stick of selenium in the vitreous form from a chemical supply house". "You should be able to secure a piece two or three inches long and about three eights of an inch in diameter for 25 to 50 cents..."

The instructions go on to describe that after rubbing a uniform coating of the selenium onto the bare copper wire previously wound bifilar around a glass tube, and which has now been heated to just the point where the selenium begins to soften, the whole thing is to be annealed in a furnace made from a tin can for the purpose, as described in the book.

[Tom WA3KLR]

Patrick,

Looks like you have accrued quite a library fine by now.  But better that than Selenium poisoning, HI.

[Opcom]

No selenium.. I had only a 3-speed Schwinn bicycle so my range was limited to the local drug store. The druggist just looked at me funny when I told him what I wanted it for. My father was reasonable but said no because it's poisonous. At least he didn't mind me reading about it. My parents used to buy books for us kids. At some point he got hold of a CdS cell and gave it to me. He knew some electronics workers and they apparently had decent junkboxes, though I knew nothing of that at the time.

I used to check those books out, and a few others like a 1950s RSGB handbook, over and over as they were in a couple of my school libraries in the late 60s through 70's. The ones I have were all bought used in the 80's. Three were 'bought' from my old grade school via donation of funds to the library. The librarian showed me on the library cards inside that hardly anyone had checked them out since, and lamented that most of the children have to almost be forced to do science projects of any sort.

There were a couple of books though that were never returned. Due to my carelessness they were totally ruined. I was mowing a lot of yards every weekend to pay their replacement cost, and just glad it wasn't in the heat of summer.

In the 'Second Book' there is a line-operated home broadcast transmitter using a 6F7 triode-pentode and 25Z5 rectifier. I didn't have either of those but I had a 6A3 and a 6K6 and a 400 volt power supply. I never got to play with it much because the first time I fired it up, the 6A3 plate started to get red and just about that time my father came into my room and told me to stop whatever I was doing because it was tearing up the TV reception. Later I showed him the project in the book and we talked about it and he told me that you can't just swap any tube for any other tube, 400 was way too much voltage for that, I best follow the directions exactly until I learn more about it, and 'no more transmitters' until then. I was disappointed until the week after, when I was presented with a tube substitution book from radio shack, as well as an old RCA tube manual and a few junk AA5 radios and used  tubes he'd gotten from a TV repairman friend of his. Still no transmitters but lots of other things to make.

[K1JJ]

Very cool on the old books. Wish I had known about that four series of electronic books for boys back then.

Yep, parts were hard to come by when we were young until we got some connections.

In 6th grade a kid came to class for show and tell with an electric eye tube. I think that was my first exposure to electronics. I went over to his house after school and the cellar was filled with his father's TV repair shop. That was unbelievable.  He sold me one of those 100-in-1  electronic experimental project kits. It had a wireless AM transmitter which soon found itself on the air.

Next door to his house was a 3 el Mosley Yagi on a roof tripod. I looked at that antenna and vowed I would have an antenna like that someday, though I didn't know what it was for. Turns out I made friends with the ham's son and explored a homebrew rack with a 10M transmitter... big rig. He also had a Hammarlund HQ180 and Valiant. The thousands of frequencies on that Valiant VFO an HQ-180 dial made it look like talking to the stars in the sky - limitless! I was super impressed.

In 1964 I got my Novice and called CQ for 3 days on 3716 with no reply on a grounded antenna.

As for parts, years later I stopped by the TV shops looking for old tube carcasses. The first stop and the owner filled my VW up with old tube TV chassis'.  The junk no one wanted anymore. I built some crazy HV supplies with the transformers in series and those old TV electrolytics flashing over all the time.  Later on I met a ham in school who took me to a military surplus store. OMG...  I immediately bought a 750TL transmitter from 1944 and converted it into a linear. It kept getting crazier after that and here I is today... :-)


T

[w8khk]

I never got to play with it much because the first time I fired it up, the 6A3 plate started to get red and just about that time my father came into my room and told me to stop whatever I was doing because it was tearing up the TV reception. Later I showed him the project in the book and we talked about it and he told me that you can't just swap any tube for any other tube, 400 was way too much voltage for that, I best follow the directions exactly until I learn more about it, and 'no more transmitters' until then. I was disappointed until the week after, when I was presented with a tube substitution book from radio shack, as well as an old RCA tube manual and a few junk AA5 radios and used  tubes he'd gotten from a TV repairman friend of his. Still no transmitters but lots of other things to make.

That sure brings back memories!  I made a device to test for Hertzian waves, a coil consisting of 4 turns 3/8 copper tubing, about 4 inches in diameter, with a variable capacitor and a 7 watt Christmas tree bulb as an indicator.

For the exciter, a pair of 6L6s in a push-pull oscillator, with a similar plate coil and a split-stator variable.  It had a 4 amp 6.3 volt filament transformer, but the plate voltage was raw, unrectified, unfiltered 120 volt AC direct from the line.  The feedback to the grids consisted of a piece of teflon wire strung through the coil tubing.  

When I placed the detector coil within a foot of the exciter, I burned out the Christmas tree bulb when tuning the capacitor.  I also found that when placed near or in the coil of the exciter, it would illuminate the full length of a 40 watt fluorescent tube.  I have no idea whether or not the plates were glowing, as they were metal 6L6s.

I had no directions to follow, but just put it together from ideas when reading other circuits.  But it did wreak havoc on the old black-and-white, and was ordered disassembled.  

That was very disconcerting to a 9-year-old!  But at least I felt certain that I had confirmed the existence of Hertzian Waves!