What did you do Today 2018

[RobinParticipant @robin]

I did Sinclair's stereo amplifiers c1973? Worked for approx. 2 seconds then were no more. With hindsight I thought I got the PSU wrong, but maybe I was an innocent bystander

[SamsarandaParticipant @samsaranda]

Bazyle, I still have a Curta calculator, in pristine condition, it was my fathers he was a surveyor by profession and used it for what were then complex calculations but nowadays are relatively simple using modern calculators, he bought it during the 50’s and I inherited it from him about 30 years ago.

Dave W

[Mark RandParticipant @markrand96270]

I had a Sinclair amplifier for about 5 years power supply, pre-amp, tone controls, rumble&scratch filters and two 20W power amp modules. It was quite reliable apart from needing a regular supply of BD138 and BD139 output transistors! Very marginally rated. Everything else was ok apart from the cheap build quality. The wooden case I put around the home-built aluminium chassis made it look quite smart.

[MuzzerParticipant @muzzer]

Back in the early 80s, Sinclair had an office on King's Parade in Cambridge, opposite the college of that name. I was an engineering student at Trinity at the time and one day I called in to have a look, as I passed it several times most days. I'd experienced some of their questionable audio gear previously and was curious to see what they were up to. It was lunchtime and clearly they all nipped out for lunch, leaving the door open. I went in anyway and had a sniff about. They had a couple of small rooms above the ground floor shop, each with a desk (or two?). Nothing technical to be seen, so clearly just an admin office. But all the way up from the front door, the stairs were piled high with returned products. I guess that was pretty much what I expected. I doubt the vast ego himself would have been there anyway.

I always found Sinclair an embarrassment, speaking as a British engineer. This was a time when we were being exhorted to buy British Leyland crap like the Metro, so stakes were lowered and he joined the race to the bottom enthusiastically. Last I heard from him, he was proposing fuel cell powered helicopters(!) – what a deluded fool. Seemed quite appropriate that he craved support from the likes of Mensa, a self-selecting, self-promoting group of snobs.

Murray

[Tony JeffreeParticipant @tonyjeffree56510]

I didn’t get any of the DIY Sinclair kit but had one of their ready built integrated amps for a while. Worked ok except for the appalling switch on thump – it annoyed me so much that I added a relay on the output to delay connecting the speakers until the output had stabilised.

[OldironParticipant @oldiron]

Posted by Samsaranda on 04/01/2018 10:47:13:

Bazyle, I still have a Curta calculator, in pristine condition, it was my fathers he was a surveyor by profession and used it for what were then complex calculations but nowadays are relatively simple using modern calculators, he bought it during the 50’s and I inherited it from him about 30 years ago. Dave

Hi Dave.

The Curta is a fabulous piece of engineering. When you look at an exploded parts diagram it is hard to imagine all those parts in one small enclosure. Is it a MK1 or 2 ? It should have a cylindrical metal box with a left handed thread for storage. We have a Mk2 that is also pristine. regards Gary

[duncan webster 1Participant @duncanwebster1]

The Curta reminds me of a thing we had in the DO in my first real job. You set it up by manipulating levers in accordance with some arcane ritual (probably involving phases of the moon and chicken bones), wound a hand till a bell rang, then wound it back one rev and read the answer off. The first electronic calculator we got at work was the size of a book and you had to sign for it in the chief engineers office. At the end of my career if the batteries in you calculator went flat they would just issue an new one, I'm not convinced they knew you could fit new batteries!

[MuzzerParticipant @muzzer]

Posted by Tony Jeffree on 04/01/2018 11:17:56:
I didn't get any of the DIY Sinclair kit but had one of their ready built integrated amps for a while. Worked ok except for the appalling switch on thump – it annoyed me so much that I added a relay on the output to delay connecting the speakers until the output had stabilised.

Haha my dad got one of their preamps with an optional "scratch and rumble" filter board. The key characteristic of the latter was the deafening noise it made when you turned the crappy plastic Sinclair knobs. This was almost certainly due to the use of preset pots for level adjustment instead of pukka potentiometers that are designed for frequent adjustment. He wasn't best impressed with his investment, having spent ages constructing a proper enclosure and PSU for them. I recall the box being lined with silver foil in an unsuccessful attempt to reduce the hum levels. I know he also had to return the actual power amps early on. And I'll never forget the turn-on thump!

I recall blowing a load of pocket money on a pair of his TDA2020 audio power IC kits that were described as indestructible. You can guess how that ended up. They were little more than a std IC from SGS, supplied with a single sided PCB. Very little information about how to heatsink them properly and of course, no heatsink was offered for sale with them.

Murray

[donkeyParticipant @donkey]

Jim nic

it was hoover washing machine motors powering the c5`s kept the hoover factory afloat in Merthyr tydfil for a few extra years.

brian

[Jim NicParticipant @jimnic]

Brian

Crikey! I didn't imagine Sinclair sold enough of the things tokeep a factory going for more than an hour or 2. Still, at least it was made in UK and every little helped.

Jim

[Anonymous]

Posted by Jim Nic on 04/01/2018 12:23:30:

Brian

Crikey! I didn't imagine Sinclair sold enough of the things tokeep a factory going for more than an hour or 2. Still, at least it was made in UK and every little helped.

Jim

Too true, I only ever saw one on the road, pulled up to some traffic lights with a dirty great HGV alongside it, the lorry driver had got no chance of seeing the C5 at all, what it was going to do when it pulled of, turned or whatever. Was frightening to watch, you'd have to have a death wish to actually ride one on public roads..

Edited By Mick Berrisford on 04/01/2018 12:49:57

Edited By Mick Berrisford on 04/01/2018 12:50:36

[BazyleParticipant @bazyle]

I think the Sinclair development was done nearby in Huntingdon or Ely. Acorn also started off in a couple of rooms up a narrow staircase on Market Square in Cambridge. Several years before the BBC computer I ventured there and they were trying out one of their boards in a slot machine. I think it was one of those or a Tangerine that was used as the first computer in Blake's 7 Liberator, before Orac.

[JohnFParticipant @johnf59703]

Hmm! just catching up after a couple of days and amusing reading the calculator threads, back in the 60's 70's I worked on production jig boring hence a lot of trig calculations all done with 7 fig logs and a mechanical Brunsviga calculator, sometime in the 70's the company bought us a Texas Instruments scientific calculator — something of a revelation but at first we would make the calculation and see the result on the screen – lacking trust we then said better just check it and back to the logs and Brunsviga ! Did learn to trust it eventually though.

Also looked at Sinclair but they were incredibly slow, you put the info in then it took what seemed an age before the result was displayed — worked OK bur not really a success in my book.

[DrDaveParticipant @drdave]

After the motor stopped working on my mill, I started to troubleshoot it today. Before stripping anything down, and prompted by Neil's suggestion of the motor being at fault, I checked the resistance across the DC motor: open circuit. I looked at the motor and remembered that it has carbon brushes; clearly the next thing to check.

I hope that this is the problem. Now, where to get new brushes for a 20 year old German motor?

[Jim NicParticipant @jimnic]

As happened with the motor on my mill, you seem to have one completely worn brush and one less so. You should be able to measure the size you need and resort to good old e-bay where you will find many sizes of carbon brush for cheap money. Watch out that the springy end is the correct size and shape for your motor and then the brush itself can be easily and gently filed to size if necessary.

Jim

[larry PhelanParticipant @larryphelan54019]

What did I do today ? Not a lot ! but will give it Hell tomorrow !

[Neil WyattModerator @neilwyatt]

I think my twin TDA2030 hifi amp may still exist. Made while I was still in school one channel used a 'development kit' board and I drew the other one up with a Dalo etch pen. A lovely old magnetic pickup module and two 8" dual cone speakers in chipboard cabs I made.

It got replaced by a Tripletone with dual concentric knobs, bits of a two-channel, four input guitar amp based on this definitely still exist….

My first 'custom amp' was an old Duette autochanger record player with the turntable replaced by a jack socket and a larger speaker built into the box. Lethal!

I then fitted a record player valve amp into the box of a defunct Trough-Line receiver. Probably the first ever stand alone Valve-preamp distortion unit

What I miss most was a distortion pedal built into a plastic stomp box from Maplin. It combined two simple 'fuzz' circuits, one using discretes, one using op amps that could be switched in series. It was a 'little' noisy but could destroy armoured vehicles at 100 metres. Called 'Doc's Monster Fuzz' it sadly got stolen. I have a recording of it in action with a 'mini phaser' and wah pedal…

Neil

[SamsarandaParticipant @samsaranda]

Hi Gary, my Curta is a mk2 complete with left hand metal case both in pristine condition, and yes a phenomenal piece of engineering condensed into a very compact space.

Dave W

[Philip RoweParticipant @philiprowe13116]

Stripped and cleaned an old 4 jaw independent chuck that had become sticky in it's operation, now works quite silkily (if that's a proper word). This chuck would have been purchasd by my late father in around 1935 and is stamped 'The Burnerd' and underneath 'Buck and Ryan'. Originally it had a backplate to fit a Myford ML2 but in the 70s this was changed to a larger backplate to fit a Super 7, being only 4" diameter I find it far more convenient for the sort of work that I do than the more usual 6" normally associated with the S7.

Phil

[duncan webster 1Participant @duncanwebster1]

Finished the rebuild of the electronics for my milling machine table drive. Mk1 had a PIC, but it wasn't fast enough really. I could have changed the code, but I no longer had the hardware to program PICs so I've re-done the whole thing with an Arduino. In the meantime of course I've now got the kit for programming PICs again, but I still have to learn how to use it. The actual drive motor is a stepper, saves having to have a declutch mechanism, and will allow me to drive it from a Division Master or similar in future

[MuzzerParticipant @muzzer]

My last foray into high-ish power audio was a 50W per channel power amp for my car when I was in 6th form. It also contained my first switched mode power supply (I ended up in a job in that field a few years later), which boosted the 12V voltage up to a regulated 60V and was the key to getting a decent output. The back seats of the car were occupied by a couple of full sized Acoustic Research speakers held in by the seatbelts. If the weather was conducive, I could park up and bring the speakers out of the car for proper outdoor stereo listening.

Murray

[Another JohnSParticipant @anotherjohns]

Today, I did not pontificate about computers.

Instead, I'm working on a batch of injectors, DAG Brown design, but "metricated" and the 13 overflow caps are now slotted, using a specially made jig and file, rather than a 4.5mm end mill.

Also figuring out how to connect the steam to cylinder line on my new Shay locomotive – it did fit, before painting! Hmmm…

John.

[EmgeeParticipant @emgee]

Dr Dave

This was quoted in a mail to me some time ago but I believe your mill is an Emco F1 so should help with sourcing brushes, contact them directly at http://www.solenttools.co.uk/

ask for carbon brushes part no STL 0406

Emgee

[richardandtracyParticipant @richardandtracy]

Muzzer,

In my 2CV there was a Tandy cassette player. 50W per channel, and every last Watt was needed to hear anything over the engine noise at 50mph. Listening was very wearing. Hi Fi was for those who didn't need to shout to be heard when travelling.

Regards

Richard.

[DrDaveParticipant @drdave]

Posted by Emgee on 06/01/2018 20:33:36:

Dr Dave

This was quoted in a mail to me some time ago but I believe your mill is an Emco F1 so should help with sourcing brushes, contact them directly at http://www.solenttools.co.uk/

ask for carbon brushes part no STL 0406

Emgee

Emgee,

Thanks for the link: I will give them a try next week.

Dave

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