4th Feb 2018, 12:27 am | #41 | |
Octode
Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
Posts: 1,377
|
Re: Weird experiments as a beginner in this hobby
Quote:
Whilst at secondary school, a group of us had access to the darkroom where we were supposed to do photography. We discovered a large box of 680mfd 35v electrolytics on a shelf. These were a nice sliding fit in the chrome towel rail. Connect 5 of those Weir power suppliers common in science blocks at the time in series to get about 80V. Place capacitor in towel rail & put a ball bearing on top. Aim at end wall & connect capacitor in reverse across the supply. Wait about 10 seconds for the terrific bang and the ball bearing to embed itself in the wall. Fall about laughing!! After quite a few of these explosions, the atmosphere was filled with probably toxic fumes If you've smelt an exploded capacitor, you will know what I mean! At the end of the lunch break we would stumble out into the corridor gasping for air: not entirely healthy, methinks!! |
|
4th Feb 2018, 12:30 am | #42 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
|
Re: Weird experiments as a beginner in this hobby
I can remember when we were at college and after physics we did communications in the same room.
After doing the cloud chamber experiment a couple of lads saved some of the dry ice and insulated it until the next lesson was under way. While the tutors were changing over they had got a beaker of water and hidden it. While the tutor was not looking they revealed the beaker and dropped the dry ice it. The beaker had also been quickly sneaked onto his desk. The tutor panicked while we all sat there grinning. The guy had only seen dry ice on old sci-fi films when the baddies are making poison. |
4th Feb 2018, 12:45 am | #43 |
Rest in Peace
Join Date: Feb 2004
Location: Hexham, Northumberland, UK.
Posts: 2,234
|
Re: Weird experiments as a beginner in this hobby
Reading your post RW, it's strange to think that when I was growing up in a village, all the neighbours seemed quite happy to let me, a fifteen year old kid repair all their electrical stuff, TVs radios, car electrics and all. Wouldn't happen nowadays. I don't repair stuff for people any more, except maybe immediate family, who hopefully aren't going to sue you if it all goes pear shaped. Regarding blame for causing interference etc. not once have I been accused of causing TVI by neighbours, despite my house being festooned with "suspicious looking" antennas of all designs, and the location being particularly poor for TV reception. Long may it last.
Alan. |
4th Feb 2018, 1:11 am | #44 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
|
Re: Weird experiments as a beginner in this hobby
I can remember trying to make an electric fly killer.
I got a line output transformer that looked like a recent replacement from an old telly that had been dumped. I took it to bits keeping the over-wind as it was on its own bobbin and wound a new primary of 20 turns with a center tap.I rigged two 2N3055s with very basic bias and a couple of caps as a multi-vibrator. It produced an inch of plasma. It was subjected to quick change of use for melting anything and everything. Fly killer of the time was better because it made them lay on there backs and spin. Who remembers what wasps used to do with that kind of fly killer? |
4th Feb 2018, 1:37 am | #45 | |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,715
|
Re: Weird experiments as a beginner in this hobby
Quote:
Anyway, being a radio lab it was bristling with test equipment, particularly Advance E1 signal generators. Someone would hide a transistor radio in the room and we would take it in turns to fire up one of the sig gens at strategic junctures. Thinking back on it I don't think he took it at all well. He had a strange turn of phrase, and would berate us with "Don't be so sophisticated" (with the stress placed on the penultimate syllable of sophisticated).
__________________
-- Graham. G3ZVT |
|
4th Feb 2018, 10:43 am | #46 |
Nonode
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,859
|
Re: Weird experiments as a beginner in this hobby
Reading the last few posts has started me off again! My first fluorescent tube experiment was a 4 foot one taped along my 150ft or so longwire aerial. With an am tx and 150w input it was fun to tune up on different bands at night to see which frequency band produced the most light depending on position along the aerial. It really was a strange site on a very dark night as we lived out in the country surrounded by fields.
The next used a 2 foot one. This was about 1971. I had a mini and made a 160m solid state tx for mobile use. It was all contained within a 12" × 6" × 2" diecast box. I used a 160m to mw converter for rx. The aerial was a centre loaded one mounted on the boot lid. It was impressive to leave the tx keyed then hold the tube close to the aerial to strike and watch it get dimmer as you moved it away. My third encounter was experimenting with static electricity on nylon carpets. The only nylon one was in the bedroom. The bed was on legs about 6" tall. One night, in partial darkness I lay on my stomach with the tube in my outstretched hand and waved the tube back and forth across the carpet under the bed, the darkest place. I found the faster I moved it, the brighter it was. Great! Until in my enthusiasm I accidentally hit it hard on a bed leg and it shattered. You can imagine the mess. Being a bedroom and likely to not usually be wearing shoes I really spent a very long time hoovering every last piece up. Rob
__________________
Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd Last edited by CambridgeWorks; 4th Feb 2018 at 10:45 am. Reason: spelling |
4th Feb 2018, 11:05 am | #47 |
Nonode
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,859
|
Re: Weird experiments as a beginner in this hobby
In 1968 I was shown how to use a Weller TCP1 to light a cigarette.
This involved replacing the tip with a 4ba steel screw. After a while, the element barrel glowed red hot, sufficient to light the cigarette. I must say, I never destroyed one iron doing this. However, with the price of spares I would not recommend doing this today. Yes, TCP1 was around 50 years ago. It was the black handle and stand with the iron hard wired to terminals next to the sponge. Another piece of knowledge that was imparted in the same factory was when my wristwatch started playing up. After being taken to someone who was an "expert" in watch repairs, I watched him (an old timer at the factory) carefully remove the back, put a few drops of meths or similar on the movement and gently blow it out with a soft blow of air from an airline. This restored it to working order. So, a few weeks later, when it played up again, I knew what to do. I was a 16 year old expert watch repairer now! I took the back off easily, put a few dribbles of the meths inside and used the airline to blow the residue away. Unfortunately, I did not realise that a full press on the trigger released a jet of air at about 100psi! (This was before the days of h&s, hence such high pressure). The old timer had only used a gentle breeze resulting from a tiny press on the trigger. The result was I was left with a watch with the escapement wheel still attached to the hairspring but dangling precariously just a few mm away from the rest of the movement. I have occasionally learnt other lessons the hard way. Such is life. Rob
__________________
Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd |
4th Feb 2018, 11:27 am | #48 | |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
|
Re: Weird experiments as a beginner in this hobby
Quote:
There was nothing whatsoever connected to the long wire. I suppose, from her point-of-view, I could see where she was coming from, but by crikey, she took some convincing! Ironically, when I did match a transmitter into it, I only affected my parents' house (the chimney and TV aerial bracket to which one end of the long wire was lashed) and the adjoining semi. But they only lost their chroma on key-down so it wasn't that bad, really.
__________________
Regds, Russell W. B. G4YLI. |
|
4th Feb 2018, 12:17 pm | #49 |
Dekatron
Join Date: Mar 2008
Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.)
Posts: 3,183
|
Re: Weird experiments as a beginner in this hobby
Hi,
Thinking about the early posts in this thread about feeding high voltage audio signals through the ground. I wonder if anyone has tried it during the annual 'Worm Charming' contest in Willaston, Cheshire? Just a thought. Cheers, Pete.
__________________
"Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..." |
4th Feb 2018, 3:16 pm | #50 |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,715
|
Re: Weird experiments as a beginner in this hobby
The false TVI clam is well known phonominum. I had far more reports of interference an SWL than I did as a licenced amateur, although, as my first receivers were super-regenerative, they might have had some merit!
Rob's anecdote about lighting cigarettes reminded me of my first position as "Junior Improver" at Granada TV Rentals, Seedley, monochrome refurb branch. A guy with the impressive title of Regional Polisher used to visit us weekly to deal with any damaged cabinets. I only remember his first name, Ted. We called him Ted de Pol. He swore the the proverbial trooper. He had great success at removing vase rings from the top of TV sets by wiping meths on the area and setting light to it, the ring would disappear before your eyes. Somehow though, when ever any of us tried the same, it always ended badly, with a CO2 extinguisher being deployed.
__________________
-- Graham. G3ZVT |
4th Feb 2018, 3:50 pm | #51 | |
Dekatron
Join Date: Jul 2007
Location: Penrith, Cumbria, UK.
Posts: 3,687
|
Re: Weird experiments as a beginner in this hobby
Quote:
The telephones were located beneath the open wire feeders in the sender hall and conveyed 100kW HF to the aerial - if matched correctly! Someone made paxolin telephone dials to replace the metal ones, and so eliminate hot fingers when 17MHz was on.
__________________
Regds, Russell W. B. G4YLI. |
|
4th Feb 2018, 4:06 pm | #52 | |
Guest
Posts: n/a
|
Re: Weird experiments as a beginner in this hobby
Quote:
|
|
4th Feb 2018, 4:27 pm | #53 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,998
|
Re: Weird experiments as a beginner in this hobby
I did a lot of playing around with Electrolysis as a kid: using different electrodes [the centre-carbons from U2 batteries, copper strips, bits of aluminium, tin cans] and electrolytes (salt-water, caustic-soda solution - yes I discovered what *that* did to aluminium and your fingers - and even human urine!)
I had an old 12/24V battery-charger as a power supply. Apart from the intriguing gases [with a hint of chlorine when using salt-water electrolyte] a homebrew electrolysis-cell could boil the electrolyte. One of my favourite tricks was to use Plasticene and insulating-tape to seal the electrodes into their container with the electrolyte, attach a length of small-bore plastic pipe [the stuff you used in aquariums] as the gas-vent, then dangle this into a bucket containing a couple of inches of water with a good squeeze of Fairy Liquid added. The electrolysis gases - hydrogen and oxygen in an ideal mix - then blew bubbles. Once you had a bucket-full of froth you dropped-in a match, with impressive results. Perhaps I should rekindle my fondness for electrolysis and try to produce that old 1920s LT-battery-recharging staple, the "Electrolytic Rectifier" ?: http://no3m.net/2016/02/electrolytic-rectifiers/ |
4th Feb 2018, 4:30 pm | #54 | |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,715
|
Re: Weird experiments as a beginner in this hobby
Quote:
__________________
-- Graham. G3ZVT |
|
4th Feb 2018, 8:43 pm | #55 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,987
|
Re: Weird experiments as a beginner in this hobby
When I was 10 I remember wiring a mike into Dads radio tuned to quiet place on scale and being able to talk through the radio. The radio was an Ecko U199 which is a live chassis, no mishaps and only found out years later.
John. |
4th Feb 2018, 9:57 pm | #56 |
Nonode
Join Date: Jun 2010
Location: Spalding, Peterborough, Cambridgeshire, UK.
Posts: 2,859
|
Re: Weird experiments as a beginner in this hobby
John, aged about 12 I had a fascination for a "must have" audio amplifier and extension loudspeaker setup. Wires all round my bedroom, ....and beyond.
I did not have a microphone though. However, a simple book (bit like ladybird, but not I think that one) had details of how to make your own microphone. This comprised a wooden base, a thin piece of card mounted vertically on it (the diaphragm) a battery, a transformer and 2 carbon rods removed from old batteries. One carbon rod was inserted horizontally in a hole in the thin card, about centre point, with a wire attached around the end of it. The other carbon rod (also with wire attached at one end) was angled at about 45 degrees from the wooden base, just resting very lightly against the first rod. The 2 wires went to a transformer, with a 1.5v battery in series with a reverse connected loudspeaker transformer. The High z secondary connected to the input of my amplifier. The idea was the tiny vibration of the card diaphragm vibrated the rods at their connecting point, thus varying the dc current in the winding a fraction. Just a simple carbon microphone really. Just how well (or if?) it worked, I cannot remember, but certainly I remember the construction details given above. Yet just another small learning step on my future career ladder. Rob
__________________
Apprehension creeping like a tube train up your spine - Cymbaline. Film More soundtrack - Pink Floyd |
4th Feb 2018, 10:22 pm | #57 |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,987
|
Re: Weird experiments as a beginner in this hobby
I can remember crushing the carbon rods out of batteries and filling a tobacco tin for a mike, Unfortunately I can not remember it working. This would have been for an intercom, I was later given a 750mw amp, wired two speakers and a DP DT switch and a load of X GPO twin cable when it was replaced from down our lane. It worked very well.
John. |
4th Feb 2018, 11:21 pm | #58 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
|
Re: Weird experiments as a beginner in this hobby
It was a messy job getting the carbon rods out of old batteries.
There must have been many telling off sessions about that construction project. |
4th Feb 2018, 11:41 pm | #59 | |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,987
|
Re: Weird experiments as a beginner in this hobby
Quote:
John. |
|
5th Feb 2018, 12:34 am | #60 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,553
|
Re: Weird experiments as a beginner in this hobby
That is all right if you do not get it on your cloths.
|