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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 3rd Jan 2020, 12:12 am   #1
Test Desk
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Default Homemade electronic components

My grandfather on my mother's side was ex RAF and I only met him a few times as he was estranged from my grandmother in Birmingham and he lived in Yorkshire. I used to enjoy reading the copies of "Practical Mechanics" he left at my grandmother's house, including the one that had construction details of an aeroplane! My mom told me he built his own radios etc and sometimes made "condensers" using tin cans. Presumably he was making paper capacitors but I don't know for sure. Has anyone else heard of this practice?
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Old 3rd Jan 2020, 12:55 am   #2
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Default Re: Homemade electronic components

Pieces cut from food cans or similar sound to me to be much to stiff and hard to handle, and also liable to have sharp edges that might puncture the insulation.

Tin foil sounds more likely, and might have been actual tin in those days rather than the aluminium foil that is in common parlance called tin foil these days.
Tea chests when used for importing tea (as distinct from later re-use as general purpose packing containers) were lined with real tin foil to preserve the aroma and flavour of the tea.
This could be salvaged, or purchased from a scrap dealer and used to make condensers, with waxed or varnished craft paper for insulation.

Cigarettes were in those days more often sold in tins, but I think that some cheaper brands came in card cartons, again lined with metal foil.

Pieces cut from food cans therefore seem unlikely for making condensers, but WERE used for the cores of home made power transformers, not just for radio sets but also for bell ringing and the illumination of models etc.
Ready made transformers were hugely expensive and could cost several days wages. A similar transformer today costs about 15 minutes wages.
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Old 3rd Jan 2020, 9:32 am   #3
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Default Re: Homemade electronic components

We used to have a few tomes called something like "Practical Knowledge" or similar back in the 60's when I was but a lad. There were construction plans for a crystal radio, in which the resistors were made by using a 2B pencil and a piece of ground glass.

I forget if there were any capacitors, and if so how they were made.

Craig
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Old 3rd Jan 2020, 9:41 am   #4
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Default Re: Homemade electronic components

Fascinating! I'm aware of my grandfather winding transformers because of the cost, but I don't know if he made any condensers... He also had a welder he manufactured in a tea chest, but I haven't dared to look inside there.

Perhaps the tin cans were for a tidy metal case, stuffed with paper and foil?
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Old 3rd Jan 2020, 10:07 am   #5
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Default Re: Homemade electronic components

In the early days making your own components seems to have been quite common practice. Here are some cigarette cards from the Godfrey Phillips' How To Make Your Own Wireless Set series, dated 1923 I believe. The one in the bottom left corner (first pic, flips to bottom right in the second pic) tells you how to make your own condenser

https://i.ebayimg.com/images/g/5WgAA...Qp/s-l1600.jpg
https://i.ebayimg.com/images/g/dmUAA...Qu/s-l1600.jpg

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Old 3rd Jan 2020, 10:54 am   #6
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Default Re: Homemade electronic components

I would expect to find examples of d.i.y. components in back numbers of "The Model Engineer and Electrician" (to give it its full title in the Edwardian era) . I have a facsimie edition of a volume from 1904 and almost every issue has a piece about an experimental electrical item made from scratch. Beer bottles filled with lead shot and wrapped round the outside with tin foil made excellent condensers for the Whimshurst machines used to energise home made X-ray machines, while home-made electric motors and batteries are other examples. Making your own components for radio would be a logical extension of the capabilities of the home constructor of a hundred years ago.
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Old 3rd Jan 2020, 11:04 am   #7
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Default Re: Homemade electronic components

Hi i use a 120pf variable cap in the matching of a small tx loop aerial. Its made from 2 cans that fit into each other. the insulation is polythene sheet the only problem is the cans rust. this idea stands the rf voltage across the ends of the loop without flashover. The cans are a Tesco baked bean can and a small garden pea can they fit into each other with around 2-3mm gap wrap sticky polythene around the inner so its a snug fit solder wires and you have a high voltage variable cap at almost no cost Mick
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Old 3rd Jan 2020, 11:06 am   #8
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Default Re: Homemade electronic components

Quote:
Originally Posted by emeritus View Post
I would expect to find examples of d.i.y. components in back numbers of "The Model Engineer and Electrician" (to give it its full title in the Edwardian era) . I have a facsimie edition of a volume from 1904 and almost every issue has a piece about an experimental electrical item made from scratch. Beer bottles filled with lead shot and wrapped round the outside with tin foil made excellent condensers for the Whimshurst machines used to energise home made X-ray machines, while home-made electric motors and batteries are other examples. Making your own components for radio would be a logical extension of the capabilities of the home constructor of a hundred years ago.
I built a Wimshurst Machine back in 1955. Managed to find two 12" diam perspex discs in a local plastic suppliers. Cut the segments from brass shim, and made the drive train from Meccano parts. Home made wooden frame. Other brass components from Woolworths brass curtain track counter.

The Leyden Jar ( capacitors ) were made from jam jars with brass shim inner and outer cylinders.

I could get a 4" spark out of the device on a low humidity day. Jam jar glass was clearly low grade because occasional sparks would short circuit through the glass!. My parents were not keen on tha fact that the device blotted out the television screen either.
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Old 3rd Jan 2020, 6:43 pm   #9
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Default Re: Homemade electronic components

There's a pair of interesting modernish books (1990s) called 'The Voice of the Crystal' and 'Instruments of Amplification'. The first describes making the components for a crystal set (headphones, detector, coil, fixed and variable capacitors) using no commercial electronic parts (OK, he does use normal wire). The second book describes making (albeit very short life) triode valves and copper oxide transistors.

I am pretty sure both are out of print now, but you might find them second-hand.
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Old 3rd Jan 2020, 7:02 pm   #10
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Default Re: Homemade electronic components

"making your own components" was - obviously - a 'thing' with prisoner-of-war radios.

Some examples I can recall are grid-leaks made by rubbing pencil-lead onto a roughened piece of Bakelite, HT-chokes made by winding wire round a bundle of nails, capacitors made from aluminium-foil (chocolate wrappers from Red Cross parcels) and the thin paper from Bibles [all dipped in candle-wax] and a tuning-capacitor styled as a huge compression-trimmer: sections of rolled-flat tin-cans interleaved with paper, a nut/bolt through the middle to adjust the amount of clamping-pressure, and a length of bamboo-boiled-in-candlewax as the adjusting-spindle.

Razor-blades - the 'blued' type - in contact with some other metal could provide a crystal-set detector. Where you got your headphones from was anyone's guess!

See https://www.bbc.co.uk/history/ww2peo...a4127870.shtml
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Old 3rd Jan 2020, 7:10 pm   #11
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Default Re: Homemade electronic components

In more-modern times, I recall a number of designs for anti-TVI filters being published in RadCom and the like, which were based around the use of double-sided-PCB material to provide the capacitors, and also a design for a "magnetic loop" transmitting antenna where the tuning-capacitor was a pair of 'plates' of PCB-material hinged so they could be moved closer or firther apart to provide a high-voltage airspaced capacitor.

Then there were the 'electrolytic rectifiers' of times-past, using chunks of aluminium and lead sheet dangling into glass jars filled with Lye. I remember trying to build one of these as a kid. It boiled-over spectacularly!!

Here's an example of the "double-sided-PCB-capacitor" filters: https://pa3csg.nl/?page_id=29
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Old 3rd Jan 2020, 9:33 pm   #12
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Default Re: Homemade electronic components

Here are a couple of examples - a variable capacitor from a peach tin, fixed condensers and grid leak. Lots of articles in the early magazines. You could make most things other than the valves.
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Old 3rd Jan 2020, 9:46 pm   #13
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Default Re: Homemade electronic components

Ah! Practical Mechanics - greatly missed.

However, there are a lot of issues on American Radio History, espcially pre ww2, including making the Luton Minor airplane

https://www.americanradiohistory.com...-Mechanics.htm


If anyone has copies or scans of the 'PraCTICAL MECHANICS hOW TO MAKE IT ' books, i'd love to borrow them

HNY

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Old 4th Jan 2020, 12:25 am   #14
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Default Re: Homemade electronic components

In my naïve youth I embarked on making a 1-valve regen rx out of a library book. It explained how the circuit worked and I took it to the nice man in a war-surplus and new-components shop who found me all the bits except the one specified as 'condenser 0.1µF 350VW'
He said he hadn't got one of those, he only had 250V or 500V or something (the thing ran on a 90V battery). So I went back to the library to find how to make a condenser, and a lot of stiff toilet paper and a roll of cooking foil later I had a contraption about the size of a toilet paper cardboard tube.

The set worked very gratifyingly and I progressed to better technologies but I didn't have the foresight to check if it would have still worked without the big condenser...
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Old 4th Jan 2020, 7:35 am   #15
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Default Re: Homemade electronic components

Electroboom made his own HV caps I think as well as the jar types.

Andy.
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Old 4th Jan 2020, 12:40 pm   #16
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Default Re: Homemade electronic components

One has only to look at what is produced in other (perhaps less western minded) areas of the world to see that people are still making components (particularly condensors) from first principles. The bean can idea, and Leyden jars, I have seen within the last couple of weeks as well as other designs of variable capacitor. Crystal radio people, particularly, make their own coils and aerial arrangements of a vast number of different, and sometimes strange, designs. Looking in some places, pretty high tech ideas can be found too. People are beginning to make allsorts using 3D printers.

I see that on other than mainstream vintage radio and similar sites there are many clever people (obviously along with others who not) who are exploring ideas much in a similar way to the pioneers from early days. These places often get a throughput of people, hence changing ideas, rather than places with steady membership on which ideas tend to follow the same thread.

I absolutely love them, although am perhaps a bit biased as I like to produce at least my own coils and also test ideas too, particularly thinking about abstract concepts.
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Old 5th Jan 2020, 6:48 pm   #17
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Default Re: Homemade electronic components

Quote:
Originally Posted by Julesomega View Post
In my naïve youth I embarked on making a 1-valve regen rx out of a library book. .
Julian,

I hope you'll forgive me for congratulating you on converting a library book into a regen rx!

Back in the 1960s I worked with a couple of "old-timers" who told me that paper and pencil grid leak resistors were standard practice for home-made receivers back in the 1920s.

In the 1990s I was asked to give a series of "practical" lectures to 2nd year undergraduate electronics students and decided on a theme of the need to understand the full range of characteristics of apparently simple components. For part of the "resistors" lecture I asked a volunteer to draw a resistor symbols on a piece of paper and then asked what its resistance was. The usual response was a blank look and the question "What do you mean, it's just a symbol, it could be any value"?

I then got the volunteer to measure the graphite trace with a multimeter, I hope making the memorable point that resistance comes in other forms than ready made components.

PMM
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Old 6th Jan 2020, 10:40 am   #18
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Default Re: Homemade electronic components

Thanks for all the replies and other sources of information. It's good to see there's still a healthy level of ingenuity among enthusiasts like my grandfather. The last time I saw him, he gave me a homemade multi-meter built into a wooden box and told me to be careful around high voltages. I was about eleven at the time! I've often thought, when doing the recycling, that there must be a use for cans that fit inside each other and mickm3for has found one. I've never made a Wimshurst machine but I was fascinated by the one in the Birmingham Science Museum. In my BT days, I remember removing a strip of perspex from the display of switchboard operator console to clean it. I laid it on the fabric seat of her swivel chair and proceeded to rub it vigorously with a cloth. I'll never forget the massive jolt I got up my left arm. Quite similar to touching the HT leads of a car distributor ( another painful lesson).
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Old 6th Jan 2020, 12:10 pm   #19
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Default Re: Homemade electronic components

I used two pill bottles to make an adapter for a rain water pipe.
The great thing about this is that the bottle sizes and top sizes vary between generic suppliers so that you can easily get two that nest to adapt two pipe sizes.
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Old 6th Jan 2020, 3:15 pm   #20
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Default Re: Homemade electronic components

Quote:
Originally Posted by mickm3for View Post
Hi i use a 120pf variable cap in the matching of a small tx loop aerial. Its made from 2 cans that fit into each other. the insulation is polythene sheet the only problem is the cans rust. this idea stands the rf voltage across the ends of the loop without flashover. The cans are a Tesco baked bean can and a small garden pea can they fit into each other with around 2-3mm gap wrap sticky polythene around the inner so its a snug fit solder wires and you have a high voltage variable cap at almost no cost Mick
That's a brilliant idea! Thanks, I will be on the lookout for tins Was the polythene sheet of the builders variety?

Any how much power were you driving the loop with?

I wonder whether Heinz cans will tolerate higher voltages over the supermarkets own brand

Last edited by PsychMan; 6th Jan 2020 at 3:28 pm.
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