Test Equipment Anonymous (TEA): Discussion and Group Therapy thread Part 2

[Zenith]

Ii's definitely worth looking out for tatty old gear, or TE which is specialised and obsolete, for parts, if it's going cheap. The case, pots, transformer, and particular components would cost a fortune if bought new. Even things like feet and knobs are surprisingly expensive new.

One of the attractions of rallies these days is picking up components. I don't see as much distressed TE going for a quid or two as I'd like.

However, I wouldn't like to think I'd paid $25 plus shipping for that poor power supply. Maybe if I'd got one which needed a mains transformer. The transformer may not have been damaged when it was dropped off a high building, or whatever happened to it.

[EC8010]

Wow! That power supply is (as the seller honestly declares) "in bad shape". Whatever happened to it to cause that? Parachute failed to open?

I didn't notice that there were piles that discriminated between quality at Crowdhill. I assumed (from equipment age) that it was all iffy. There used to be an electronic junk shop at Southampton that went by the name of "Southern Science and Technology Forum Stores". It was where university junk went. Wound iron components were sold for 20p/lb. I went there a lot. Bought my first oscilloscope there for £4, plus 25p for a mains lead (probably Bulgin 5A). The Crowdhill trove reminded me a lot of Forum Stores.

Yes, component prices have gone through the roof since Covid. I'm so glad I bought lifetime stocks of semiconductors beforehand. I never used to bother salvaging wafer switches, but the fine cutters, desolder braid, defluxer, isopropyl alcohol, and Silver Dip come out now, especially if the wafers are ceramic. Cleaned wafers then go in polythene bags or lunch boxes. By the way, you have to be very careful with Silver Dip as it works by corroding away the surface of the silver, so you absolutely want minimum immersion time and to dilute it away immediately. The alternative with stud switches is Brasso on paper to polish their contact surface.

When I was a kid, I couldn't afford new components, so I used to walk four miles to the Rediffusion repair shop and salvage components from the televisions in the skip outside.

[Zenith]

[I had a 1740, and quite liked its large screen and 50ohm input. Arguably 465s are better, but it is a very closely run race.

I didn't like the way the timebase switch abraded PCB tracks (fixable), and I believe the bridge rectifier is weak. The timebase markings had poor contrast and were difficult to read. I simply printed a new one, and stuck it on top of the old scale, under the plastic. I may still have the file, if you want to replace yours. EDIT: I've found it.

I've seen nowhere near as many HP 17XX scopes as Tek 465s and 475s on my travels. Usually people ask a lot more for them, £40 to £80. I don't like that they are quite long. I don't know how the performance compares with Tek.

I've only given the pair a cursory looking over. It looks like a good one and a parts mule may come out of it.

You've had some experience of 1740s, so if I come across anything I'm not sure of, I'll send a PM. They are quite a long way down the to do list.

[Zenith]

When I was a kid, I couldn't afford new components, so I used to walk four miles to the Rediffusion repair shop and salvage components from the televisions in the skip outside.

I don't think there are any electronic junk shops left. i used to go to Centre Electronics in Birmingham, which closed abut 20 years ago.

Taking old valve tellies and radios to bits for the parts. Those were the days. In modern consumer equipment, there's surprisingly little that's salvageable.

[tggzzz]

Wow! That power supply is (as the seller honestly declares) "in bad shape". Whatever happened to it to cause that? Parachute failed to open?

Anecdotally the Israeli equivalent is "run over by a tank"

There used to be an electronic junk shop at Southampton that went by the name of "Southern Science and Technology Forum Stores". It was where university junk went. Wound iron components were sold for 20p/lb. I went there a lot. Bought my first oscilloscope there for £4, plus 25p for a mains lead (probably Bulgin 5A). The Crowdhill trove reminded me a lot of Forum Stores.

Was that the place in a ?nissen? hut in school grounds between the University and the Common? I still have at least one component I bought there, somewhere in the cave.

I believe there was also a Greenweld in Southampton.

By the way, you have to be very careful with Silver Dip as it works by corroding away the surface of the silver, so you absolutely want minimum immersion time and to dilute it away immediately. The alternative with stud switches is Brasso on paper to polish their contact surface.

Oxygen corrodes the silver too I rather like the graphite/silver contacts, typically found on decent decade resistor boxes. Rotate them a few times, optionally with IPA, and they work again.

I wonder whether one of the DeOxits would be useful. A tiny drop of D100 is useful for many contacts, but I've always hesitated to use it on anything metrological, e.g. a Guildline 4 terminal resistor.

When I was a kid, I couldn't afford new components, so I used to walk four miles to the Rediffusion repair shop and salvage components from the televisions in the skip outside.

Oh, yes indeed. Add shortwave radios in secondhand church sales.

In my school's darkroom at the back of the senior physics lab I found some PCBs under the benches on the floor. The physics master was more than happy for me to take some to salvage the components.

Then there was the local tip in Epsom, a very affluent area. I once saw a desk-sized Olivetti computer there. Or perfectly good carpets and cookers. ISTR that after I left the council had to clamp down on people searching cars in the queue waiting to enter to the tip!

[tggzzz]

I don't think there are any electronic junk shops left. i used to go to Centre Electronics in Birmingham, which closed abut 20 years ago.

I believe Birketts in Lincoln is still there, run by his daughter. My 1740 came from there.
https://rsgb.org/main/blog/news/silent- ... pril-2022/

~1990 there was Target Electronics at the bottom of Stokes Croft in Bristol. Not sure when it disappeared, probably in the mid-late 90s.

[Zenith]

Ii met Birkett once. He had a stall at a radio rally in Worcester. I bought some germanium diodes from him. That must have been around 2001. It would have been a long haul to his shop in Lincoln.

Target Electronics was a hobbyist electronics shop which was eclipsed by Maplin, which was more accessible and had a much larger stock. Hobby electronics seemed to fizzle out around the mid 90s. Target was still open in 2004. By then there were a few items of electronic stock, but it was mainly a computer shop. They sold some new stuff, but had a lot of recycled computers and parts. I went down there to buy some second hand RAM.

I've no idea whether they are still going. I suspect they are long closed. There aren't so many computer shops around these days, and at the time Target seemed like a shaky operation.

[Zenith]

I believe there was also a Greenweld in Southampton.

I think it was the only Greenweld. I mail ordered from them, when they had a sale. 250 assorted transistors for £1.25. 250 assorted 1% and 2% resistors for £1.25. There was easily enough good stuff in their assorted bags to cover the cost.

They moved increasingly to computer junk and at one time Sinclair C5 parts.

I'm sure they went bust and were reincarnated. They're still going now.

http://www.greenweld.co.uk/

They have a very patchy electronics stock but also books, novelties and things for hobbies.

[tggzzz]

Ii met Birkett once. He had a stall at a radio rally in Worcester. I bought some germanium diodes from him. That must have been around 2001. It would have been a long haul to his shop in Lincoln.

Target Electronics was a hobbyist electronics shop which was eclipsed by Maplin, which was more accessible and had a much larger stock. Hobby electronics seemed to fizzle out around the mid 90s. Target was still open in 2004. By then there were a few items of electronic stock, but it was mainly a computer shop. They sold some new stuff, but had a lot of recycled computers and parts. I went down there to buy some second hand RAM.

I've no idea whether they are still going. I suspect they are long closed. There aren't so many computer shops around these days, and at the time Target seemed like a shaky operation.

Target electronics: https://www.bristol.org.uk/info/645/ But if you look at gurgle maps/streetview, you will see signs still up in 2008, but the building hadn't quite fallen down in 2017.

It always was shaky, and I wondered how it stayed afloat. Curiously I visited it in the early-mid 70s, when my mother took a trip back to see her old haunts.

[Zenith]

Target electronics: https://www.bristol.org.uk/info/645/ But if you look at gurgle maps/streetview, you will see signs still up in 2008, but the building hadn't quite fallen down in 2017.

It always was shaky, and I wondered how it stayed afloat. Curiously I visited it in the early-mid 70s, when my mother took a trip back to see her old haunts.

From that link you gave there are several reviews.

A review of Target Electronics by Bob written on Wednesday 29th of November 2017

Target Electronics has been closed for a number of years. You might want to check that sort of thing before you go ranting online..

Judging from the 2008 Google Maps picture, it must have been closed a year or two by then. I'd guess when I went there in 2003 or 2004, it hadn't got long to go. One of the things I bought was a new CPU fan. I took the precaution of opening the box before leaving the shop, and it had the sort of dust covering which comes from a few hundred hours use. "Ah, One of our customers has pulled a fast one!", said the owner. Right. I wasn't impressed. Not an establishment I was disposed to do business with again.

[EC8010]

Yes, Forum Stores was indeed the Nissen hut by the school. It later moved back to the university and I bought a 59" steel rule from there (£1), and also a Tek 545 oscilloscope for £10, on its trolley.

[EC8010]

I scrapped the Solartron Varipak power supply last night; it was bought primarily for its 20H HT choke. Which turned out in this Varipak to be made by Woden (I've seen some terrible transformers made by them, so that was worrying). But I've just measured the choke and it's surprisingly good. You'd expect a choke's impedance to be a diagonal line up to resonance, and that's broadly what we see. But look carefully, and you see that the rising line is actually two different lines joined by an inflection. What you're seeing there is core losses, both hysteresis and eddy current. That's why we need to split the inductance in two and add a loss resistance. Above resonance, we see shunt capacitance, and the model holds until we hit another resonance beyond 100kHz. But despite all the imperfections, it's still a very respectable series impedance up to 100kHz. An LC filter before a regulator makes for good interference rejection.

[Zenith]

A 20H 100mA choke from Sowter is about £125, so a good deal.

Then the transformer and other bits recovered may be good.

[Robert]

Apparently the Crowdhill stuff has gone "All items have now been disposed of..."
Probably just as well and my work trip is delayed.

Ahh surplus stores. I started interest in electronics when I was in Northern Ireland. No surplus or component dealers anywhere near and the local TV repair shops were reluctant to sell components. I first bought from Greenweld and Birkett by mail order back then. Remember postal orders? But stuff did turn up at the two local scrap yards. One in particular dealt with industrial stuff ad would let me wander around. Notable items were a Solartron 1440 'scope and a Wayne Kerr LCR bridge. The pulling the colis off town was one of the test sites for system X telephone exchanges. One day I went to the scrap yard and there was a guy pulling the coils off brand new Post Office Relays for the copper. I pointed out to the boss that most of the contact sets they were throwing in the mixed scrap had notches in the end and this indicated that the contacts ere Platinum. He seemed cynical but next time I visited he thanked me and I never had to pay for anything from the yard from then on
I went to college in Bristol and was a frequent visitor to but impecunious customer of Target electronics in Cherry lane. It's now an empty lot which is weird I guess there must be some issue with ownership or debt owed. There was also Marshalls further up Stokes Croft towards Gloucester road. The were not surplus and were eventually taken over by rivals Maplin. The shop is still there, a microbrewery by the look of it.
After some time in the channel islands and south wales (no surplus) I settled in Christchurch on the south coast. Bournemouth had a Radio Shack and a store that sold bits for "hi-fi" but Southampton had Maplins and Greenweld. There was also a guy who sold interesting but overpriced stuff from the front room of his house.
Further afield from back when I was in Bristol and started driving there were visits to Stewart of Reading (still going but haven't been there for years), John's Radio and M&B radio in Leeds and Anchor Surplus in Nottingham during the nineties. Visited Birketts in person a couple of times.

[tggzzz]

Remember postal orders?

Oh yes!

But they only worked in the UK. To buy stuff from the USA you needed an International Money Order, and about 6 weeks for shipping by sea.

Bought an early digital clock IC, MM5314, and six "large" 7 segment displays (i.e. 0.5" high), and made the first digital clock most of my neighbours had seen. One hated it, since she could see the seconds of her life ticking away.

Still have the clock, still works, but converted to a vetinari clock by adding/subtracting mains cycles on its clock input.

[Zenith]

Apparently the Crowdhill stuff has gone "All items have now been disposed of..."

Let me guess. A gold bug arrived with a big van, looked it over, flashed £200 readies, they were getting fed up with it, and they bit. Job done.

Probably just as well and my work trip is delayed.

You looked it over and came away with what you thought were choice bits. As a seasoned campaigner little of value is likely to have escaped your attention. But you do have TEAS gnawing at you. Regard it as divine deliverance that a line has been drawn under the Crowdhill trove

Ahh surplus stores. I started interest in electronics when I was in Northern Ireland. No surplus or component dealers anywhere near and the local TV repair shops were reluctant to sell components. I first bought from Greenweld and Birkett by mail order back then. Remember postal orders? But stuff did turn up at the two local scrap yards. One in particular dealt with industrial stuff ad would let me wander around. Notable items were a Solartron 1440 'scope and a Wayne Kerr LCR bridge. The pulling the colis off town was one of the test sites for system X telephone exchanges. One day I went to the scrap yard and there was a guy pulling the coils off brand new Post Office Relays for the copper. I pointed out to the boss that most of the contact sets they were throwing in the mixed scrap had notches in the end and this indicated that the contacts ere Platinum. He seemed cynical but next time I visited he thanked me and I never had to pay for anything from the yard from then on

From the 50s there were military surplus stores in mainland UK selling off WWII surplus. In big cities they tended to aggregate; Alum Rock Road in Birmingham, Edgeware Road and Tottenham Court Road in London. Lesser cities would have a place such as Porter's in Worcester. Usually, if you were interested in electronics in the 60s and didn't live in a big city, you bought mail order through advertisers in Practical Electronics or a similar rag. Rasiospares, now RS, made it clear they weren't interested in messing with amateurs and numerous small mail order businesses started. Maplin rode the amateur electronics wave and eventually had shops even in small towns.

I went to college in Bristol and was a frequent visitor to but impecunious customer of Target electronics in Cherry lane. It's now an empty lot which is weird I guess there must be some issue with ownership or debt owed. There was also Marshalls further up Stokes Croft towards Gloucester road. The were not surplus and were eventually taken over by rivals Maplin. The shop is still there, a microbrewery by the look of it.
After some time in the channel islands and south wales (no surplus) I settled in Christchurch on the south coast. Bournemouth had a Radio Shack and a store that sold bits for "hi-fi" but Southampton had Maplins and Greenweld. There was also a guy who sold interesting but overpriced stuff from the front room of his house.

I always thought Radio Shack was overpriced and thoroughly crap.

Marhalls seemed to concentrate on valves, but in the 70s expanded and had a shop in the Straits Parade, Fishponds, in Bristol, and another in I think Wolverhampton. They didn't last long. They vanished after that. I've never heard they were bought out by Maplin. As for Target, I went there in the late 80s and bought a 2N3055 for 50p, which was about the going rate. Someone at work told me me they were better for electromechanical stuff such as relays. Maplin had a better range and easier parking. My next involvement with Target was about 15 years later. To say I was thoroughly unimpressed is understating it.

Further afield from back when I was in Bristol and started driving there were visits to Stewart of Reading (still going but haven't been there for years), John's Radio and M&B radio in Leeds and Anchor Surplus in Nottingham during the nineties. Visited Birketts in person a couple of times.

I've bought a couple of things from Stewart of Reading and visited there. He's solid. John's Radio and M&B radio in Leeds I think had both ended by around 2005. I bought a couple of things from M&B and they were good to deal with. I arranged a trip to Telford Electronics around 2002 and came back with a couple of things. The bloke seemed detached until I noticed an air rifle in the corner, which he used to bump off magpies when things were quiet. Then he came alive. I explained it would be easy to wind it up into FAC territory by buying an Ox Spring kit, but he'd better not get caught. He said he thought he was unlikely to be caught and would look into it.

Anchor Supplies in Nottingham is still going but looking at their website, it isn't as interesting as it used to be.

[mansaxel]

With hi-fi they were talking about tangible things, such as performance measurements, until around the mid 80s. After then, I agree with tggzzz, it became like reading reviews of wine. "This amplifier has a firm but not strident bass, some loss of control in the mid-range, the treble is frighteningly revealing". I suppose by then what was practically a perfect audio amplifier could be sold for about £250, but they still wanted to sell £2,000 plus ones.

I've no idea about loudspeakers. I assume they've gradually improved as better materials and techniques have been developed.

Today, speakers are the interesting frontier. And, of course microphones. What has happened the last 20 years that is relevant (not a load of wank but actual progress) is

• Measurement in time and frequency has become cheap
• Amplifiers are cheaper.
• Active crossovers as well
• Meaningful double blind listening tests have been developed and are used by industry
• Materials science has improved.

This all together has led to much better speakers at a set price point. Active and / or corrected speakers with a sensible dispersion and a good frequency response now are possible, if not the norm.

Energy transformation remains the interesting part. The electronics are mostly known by now.

[EC8010]

Agreed on all those points. But they've only affected professional audio. Consumer audio continues to ignore active crossovers, selling mega-expensive loudspeakers having passive crossovers that require a wastefully powerful amplifier to drive their crippling load. An active crossover implemented in digits allows the inevitable delay (due to low-pass filter) in the drivers to be corrected. That's impractical in passive loudspeakers, yet makes all the difference in the world.

[tggzzz]

And consumers continue to ignore even that. Consider the tinny sounds emitted by small speakers in phones etc.

Yes, they are better than the handheld trannies of our youth, but that's a very low bar.

[EC8010]

As an old fogey, I'd point out that the pop/rock of today is rubbish compared to that of the 50s to 80s. So there's no incentive for quality reproduction. And in the race to the bottom in cheapness, a lot of current recordings are of poor technical quality even before reaching the bottle neck of MP3. I hardly have anything recorded after 1990 because I know it will be horribly compressed. After a few tracks of Amy Winehouse, the relentless pummelling drives me away even though she had a wonderful voice.

[Zenith]

As an old fogey, I'd point out that the pop/rock of today is rubbish compared to that of the 50s to 80s. So there's no incentive for quality reproduction. And in the race to the bottom in cheapness, a lot of current recordings are of poor technical quality even before reaching the bottle neck of MP3. I hardly have anything recorded after 1990 because I know it will be horribly compressed. After a few tracks of Amy Winehouse, the relentless pummelling drives me away even though she had a wonderful voice.

Others have noticed and studies have been done on the dwindling vocabulary and melodic complexity of pop music.

https://www.youtube.com/watch?v=IP0wuwJBdMI

[tggzzz]

As an old fogey, I'd point out that the pop/rock of today is rubbish compared to that of the 50s to 80s.

Up to and including the 1950s, rock did not exist and pop was dominated by "Tin Pan Alley", where singers bought songs from composers. The composers tended to ape the big budget musicals of the time, and had a herd mentality. Pop was dreadful, being cute (e.g. how much is that doggie in the window) or bubblegum about generic teenage angst. Reproduction was poor, even on high quality equipment - especially bass.

By the end of the 50s, that was becoming less true; rock was beginning to have an effect and to change things. Tinny trannies weren't much worse than ordinary equipment.

The 60s and 70s saw the rise of singer/songwriters, where skilled individuals experimented wildly and often managed to got people to buy their weird individual stuff. The experiments often made use of bass and treble sounds that older equipment didn't reproduce; equipment improved and people noticed. Positive feedback in action.

Unless you were listening whatever happened to be on the radio, listening to music required stopping doing other things, and putting your choice on the turntable.

In the mid 80s, tin pan alley started to reassert itself, e.g. Stock Aitken Waterman. They approached composing as an industrial exercise, and crafted a sound that worked OK on poor equipment in a noisy environment, e.g. car radios or on the train.

Your choice of music started to be available anywhere and anywhen, due to the Sony Walkman and portable CD players.

So there's no incentive for quality reproduction. And in the race to the bottom in cheapness, a lot of current recordings are of poor technical quality even before reaching the bottle neck of MP3. I hardly have anything recorded after 1990 because I know it will be horribly compressed. After a few tracks of Amy Winehouse, the relentless pummelling drives me away even though she had a wonderful voice.

Nowadays music is everywhere, and is merely part of the background hum.

Norman Spinrad was a good SF writer. One of his novels (Little Heroes) predicted, in 1987, the music trends we now see.

[MED6753]

As an old fogey, I'd point out that the pop/rock of today is rubbish compared to that of the 50s to 80s. So there's no incentive for quality reproduction. And in the race to the bottom in cheapness, a lot of current recordings are of poor technical quality even before reaching the bottle neck of MP3. I hardly have anything recorded after 1990 because I know it will be horribly compressed. After a few tracks of Amy Winehouse, the relentless pummelling drives me away even though she had a wonderful voice.

Others have noticed and studies have been done on the dwindling vocabulary and melodic complexity of pop music.

https://www.youtube.com/watch?v=IP0wuwJBdMI

Notice that most current adverts, TV shows, movies, etc don't play contemporary music because as you stated, it's drivel.

Related. IMHO the most iconic, famous, and instantly recognizable rock song intro is this...

https://www.youtube.com/watch?v=nrIPxlF ... rt_radio=1

[Zenith]

Related. IMHO the most iconic, famous, and instantly recognizable rock song intro is this...

https://www.youtube.com/watch?v=nrIPxlF ... rt_radio=1

It's subjective of course but for me me it's this

https://www.youtube.com/watch?v=a5Atiz3PgCM

Jack Bruce and Pete Brown had been working all night on a track to fill in the LP (album) they were committed to. Pete Brown, who was of poetic turn said,
"It's getting near dawn and lights close their tired eyes". Bruce laid down a bass riff. The rest flowed.

Jack Bruce said bass had been explored completely by Bach. It reminds me of the realisation that radar signalling processing had been exhaustively investigated by bats a few million years ago.

I don't have much music recorded since 1990 nor have I found much interesting. I'm ashamed to admit it, but I make an exception for Baby Metal. It appears to be an entirely manufactured act featuring three little Japanese girls who shout and dance in front of heavy rock session men.

https://www.youtube.com/watch?v=-UGdYgXcSxU

Others I'd pay to see include The Mediaeval Baebes

https://www.youtube.com/watch?v=RXrdfTSLWCY

and Postmodern Jukebox.

https://www.youtube.com/watch?v=aLnZ1NQm2uk

[MED6753]

Related. IMHO the most iconic, famous, and instantly recognizable rock song intro is this...

https://www.youtube.com/watch?v=nrIPxlF ... rt_radio=1

It's subjective of course but for me me it's this

https://www.youtube.com/watch?v=a5Atiz3PgCM

Jack Bruce and Pete Brown had been working all night on a track to fill in the LP (album) they were committed to. Pete Brown, who was of poetic turn said,
"It's getting near dawn and lights close their tired eyes". Bruce laid down a bass riff. The rest flowed.

Jack Bruce said bass had been explored completely by Bach. It reminds me of the realisation that radar signalling processing had been exhaustively investigated by bats a few million years ago.

I don't have much music recorded since 1990 nor have I found much interesting. I'm ashamed to admit it, but I make an exception for Baby Metal. It appears to be an entirely manufactured act featuring three little Japanese girls who shout and dance in front of heavy rock session men.

https://www.youtube.com/watch?v=-UGdYgXcSxU

Others I'd pay to see include The Mediaeval Baebes

https://www.youtube.com/watch?v=RXrdfTSLWCY

and Postmodern Jukebox.

https://www.youtube.com/watch?v=aLnZ1NQm2uk

"Sunshine of Your Love" is excellent too.

When "Satisfaction" was released here many famous bible thumpers wanted it banned because of the "suggestive" lyrics and they especially got their panties in a knot over Mick's "girly action". Funny how many of those same famous bible thumpers in later years were found to be perverts or thieves.