Practical Wireless Winton amplifier from 1979.

[@revolvingtoto007]

not edited ? well that is no problem , love your vid's ,extreme rare in these times to see a real professional technician 🙂

[@michaeldranfield7140]

Thankyou for that .

[@vulgivagu]

I still have a Sinclair X10 amplifier that I built in kit form .This was 1969. Turned it on to see if it worked as I haven't run it for 20 years and it is still working. The Sinclair FM radio tuner kit same vintage was an incredible piece of work

[@michaeldranfield7140]

I remember one that was PWM but cant remember if it was X10 or X20.

[@bobp6742]

Back in 1974ish me and my science teacher made a project out of practical wireless it was a TV game pong. I think we bought ready made circuit boards. It proved very popular once built everyone wanted to play with it, we built it as part of my CSE practical exam but the school wouldn't allow me to take it home when I left school it was placed in a cabinet at the entrance to the school but from what I heard it ended up just being chucked in the bin 20 years ago.

[@michaeldranfield7140]

I remember it well, it was a huge big console with rows of TTL chips , no LSI chips until about 1976 when the pong game was just one dedicated chip .

[@bobp6742]

@@michaeldranfield7140 The pots were mounted on the top of the panel so the players had to sit next to each other, within nudging distance 🤣 good times.

[@MichaelBeeny]

The power amplifier board has been lifted from the Hitachi application notes. This section was also available as kit from many of the retailers of the day in Edgware and Tottenham Court Road. The basic circuit could be up rated to 100 watts. A powerful amp in its day. I must have built over 15 of those kits for a number of applications. Everyone worked first time. I never had any back blown up or other faults. They sounded very good if I recall. Funny thing is, I had not heard of this complete project before. Like you I collected every issue of PW and all the other such magazines of the time. More like a Bible than a magazine.

[@sw6188]

This series of Hitachi MOSFET devices were super-reliable. In all of the amps I have seen or had in for repair that use them I have only ever seen ONE device failed, and that was because the owner put nails in place of the fuses. Other amps have had blown fuses but all the outputs were just fine. Perreaux Audio (from right here in NZ) built a whole range of power amps back in the 80s using these MOSFETs. One of their biggest amps could deliver 1 kW RMS into a 4 ohm load.

[@michaeldranfield7140]

It has been suggested that the pcb could have been brought ready made and that would account for the different soldering , I stopped buying the magazines about 10 years ago, there's no good projects anymore and everything is software driven which is no fun to me .

[@loveuk4britishpeople]

Memory lane Michael. My era. My electronics career started with getting Televisions off the tip and repairing them. Working in the controls industry now and still use the same fault finding skills on million pound machines that I learnt when I was a boy.

[@michaeldranfield7140]

Seems that a lot of people like these memory lane trips , more coming !

[@andygozzo72]

maplin did a design and kit for a mosfet amp in the early 80s, i still have the magazine featuring it

[@jimsimpson1006]

I well remember drooling over this design in the March '79 issue of P.W. Unfortunately, I never got round to building it as I had no cash to spare at the time.

[@michaeldranfield7140]

this would have been a lot of money to spend on something home made at the time and its for this reason I wouldn't think there are many of these about .

[@Rollin-Rant]

I used to build quite a few projects from PW but not this one, as that was more than a months wages for me at that time, thanks Michael for the memorable moments and thanks for sharing 👍.

[@michaeldranfield7140]

yes it was expensive for an amplifier , Im sure you could buy commercial amps for less back then .

[@jo0ls]

I built a later model a few years later in the 80s. I was a teenager in Didsbury. Mine was very badly made, lol. I got speakers from wilmslow audio.

[@jo0ls]

My dad had to send it back to get it working to be honest. They all had a good laugh, and I was told to practice soldering to be quicker as I had burnt a transistor.

[@PRDowding]

I have a pair of Maplin MOSFET 50W amplifiers from the early 1980's that if i remember rightly uses the same Hitachi MOSFET's as in the Winton. I still regularly use them as the output stages of a NAD amplifier, on my Hammond organ.

[@michaeldranfield7140]

Quite possible , these FET s are rare now , I have a vague recollection of the amplifiers in the Maplin magazine , back then I'm guessing as they were a new invention a lot of new designs would feature them .

[@peterensinger1770]

I enjoy your videos as they bring back fond memories from my youth. The power amplifier section of that amp looks very like th hitachi reference design for those transistors I have built many of this design mostly the one published in the Maplin Electronics magazine it originally appeared as a part of a guitar amp but the power amp section was subsequently published in a later issues of the Maplin magazine it was published a couple of occasions later with different output transistors and more power output the original guitar amp had a power of 75 watts then the latest incarnation of the power amp was rated at 150watts with a suitable power supply. i still have one(stereo pair) of the Maplin amps in my workshop i built. that amp is still working well. This amp must be nearly 40 years old now.. Keep up the good work, Micheal. Peter Ensinger M7DTK

[@michaeldranfield7140]

I have this picture in my mind of a couple of VFETS on a small aluminium heatsink that you were suppose to bolt to a much larger sink published in the Maplin magazine , I have quite a few maplin magazines in the loft I must get out one day .

[@peterensinger1770]

@michaeldranfield7140 Yes you are correct the two VMOSFETs in the to3 packages were mounted on a piece of aluminium angle, which was bolted to a larger heat sink. This fixing of the output transistors was also the mounting method for the pcb too.

[@carlrobson5745]

My late dad used to by those magazines he probably built some of the smaller ham radio projects but definatley built the heathkit projects, I used to dabble with the magenta/maplin and sometimes the projects in the everyday electronics as a teenager now in my 50's just no time.

[@michaeldranfield7140]

Sadly I never did Heathkit, just a little before my time but I have a few heathkit items in my collection .

[@johnrudd9550]

Nice bit of kit, well put together…thanks for sharing..

[@michaeldranfield7140]

Thankyou for that .

[@ralphj4012]

Fascinating, don't remember that one (but then I don't remember what happened yesterday). Interesting (to me anyway) that the photo on the front cover of the mag shows smaller main smoothing caps than those shown in the layout on page 47 and the finished product. I pondered whether the eventual cap working voltage was higher or they selected a lower cost cap in practice.

[@michaeldranfield7140]

Correct it does but the one in the magazine seems to be the prototype so may be it was upgraded at some time .

[@user-rf9me7xm1w]

Very nostalgic, I designed and built a number of hi-fi amps back in the day. It would have been interesting to have connected a sig gen and a scope to check for cross over distortion when on full load. My output stages were also class AB configuration but used 2N3055's as the main drivers. SN741 op-amps were sometimes used in the pre-amp stages. I also built some impressive sub woofers using fourth order filters, 100 watt power amps and 15 inch speakers.

[@michaeldranfield7140]

A full refurb is on the cards but not just yet ,I have other projects I'm currently working on .

[@michaelclutton8446]

I can remember those PW covers from all those years ago

[@michaeldranfield7140]

I need to get them in some sort of order one day !

[@kendom33]

Great video Michael thank you. Looks as though it was assembled by two different people. One did the pcb

[@michaeldranfield7140]

You may well be right , it could be the main pcb was available ready made ?

[@darrenmurphy6251]

my hifi amp is home made based on the hitachi text book opamp design using genuine 2sj50 and 2sk134 i bought in early 90,s i love it ,theres only one cap in the signal path ,and it sounds so clear and detailed. it sounds a little soft on top end (gate capacitance causing slow slew rate? ) but its so livelly mids and low end even at low volume and its really noticeable how tightly it keeps even cheap speakers under control ive got heatsinks from a fruit machine and home made hand drawn pcbs the case is an old sony tape deck the only parts i needed to buy was a 300va torroid and the vmosfets i tried many times to make bipolar amps but never got thermal runaway under control, so mosfets were a godsend and sounded far more punchy aswell

[@michaeldranfield7140]

Back then the vertical channel mosfet would have been ground-breaking technology with the negative temperature coefficient and I would imagine a lot of commercial amplifiers used the same transistor line up , I know there were several designs published in the Maplin magazine for amplifier only modules with silly output powers , must get them out the loft and have a look one day .

[@manolisgledsodakis873]

When I was at university, my roommate built the PE "Gemini" stereo amplifier. See Practical Electronics November 1970.

[@michaeldranfield7140]

I remember it well , it had Blue sides and a cream front on the case .

[@steveurquhart5895]

Really enjoyable video thanks, A fantastic kit.👍

[@michaeldranfield7140]

Thankyou for that .

[@telescopefred]

I built one of these from the kit back then and still have it driving a pair of B&W DM11 speakers. I remember modifying it by piggy backing an extra switch at the back of the original switch bank to break the lines on one of the inputs because there was a momentary feedback went through the amp when switching either to or from the turntable input which blew the tweeters in the B&W's . Luckily new ones were available from Wilmslow Audio who were close to me. I haven't powered it up for some time but will dust it off and see if it still performs

[@michaeldranfield7140]

That's 3 still in circulation then from the other comments ! still pretty rare though I think .

[@rog2224]

£110 in 1979 is, according the calculators I used, around £700 in 2024.

[@Chris558576]

Nice one, i am motivated to find my Henrys Radio Transistor HiFi 10 amplifier now. Got to be 1960s and full of Germanium.

[@michaeldranfield7140]

I remember the thick Henrys Radio catalogue.

[@perkulant4629]

Very cool, I was born in 1986 so too young. Looks like it would have been a nice project. You going to restore it?

[@michaeldranfield7140]

Yes , it will be fully restored one day .

[@stewartdahamman]

Amazing - you my favourite Amber fish

[@michaeldranfield7140]

Thankyou .

[@sw6188]

Are those purple caps Matsushita brand?

[@michaeldranfield7140]

Sorry I dont know , RS use to market some purple caps but they were made by Dubillier.

[@GaryB007]

I came across an old forum thread with info about this recently. The original designer Edward (Ted) Rule commented on the thread.

[@michaeldranfield7140]

would be interesting to know more about the company .

[@andic6676]

Looks a well made kit. Could there be a little DC on the pots?

[@michaeldranfield7140]

Yes it could be but I think more likely to just need cleaning due to age .

[@michaelturner4457]

Many Practical Wireless are available online as scanned PDFs, along with Practical Electronics, Elektor, etc.

[@michaeldranfield7140]

Not as good as having a paper copy though .

[@sw6188]

@@michaeldranfield7140 You're dead right - paper copies are the best. The trouble is they take up a lot of space, and most of us these days don't have the luxury of large storage areas. Paid storage units are doing very well out of us collectors, as they often the only places we have to keep things.

[@aroundthebush8514]

Love this as usual Michael!

[@michaeldranfield7140]

Thankyou for that .

[@killcar5nbike2]

Aren't those lateral channel FETs? Predecessors to the 2SK1058/2SJ162.

[@sw6188]

That's what I was thinking as well. They are in the same family as 2SJ49, 2SJ50, 2SK134, 2SK135 etc which are all lateral devices.

[@leeselectronicwidgets]

Nice! I'm surprised it's only 50w per channel given how much the VMOS fets can dissipate. They must have kept the DC rails quite modest then?

[@ukfmcbradioservicingTango21]

It'll be real watts & not b/s watts! Richard, G0OJF

[@michaeldranfield7140]

The heatsinks on the back are very small even for 50 watts , to get more power you would need a bigger case to accommodate larger heatsinks .

[@BongbongA99]

Wow, that's a bit of a turn up isn't it Michael! I wonder what sort of record player cartridge(s) it was geared up for. When you were flicking through those PWs, I homed in on the one with the 'free nut runner'. I still have mine right here - still as orange as ever. Thank you for the trip down memory lane.

[@michaeldranfield7140]

Dont know where my nut runner is off the top of my head but quite recently I found a wire bending gauge in bright orange that either came free with either everyday electronics or practical wireless.

[@peterbell4662]

Mine was perhaps an early version .. replace the vo;ume control - carbon track now becoming knackered . They used to run really hot - extra heat sinks to the back panel - still use mine with update to the output transformers .. prices useing kit never £ 100 plus -

[@michaeldranfield7140]

The heatsinks are very small so the 50 watts per channel would only be intermittent use .

[@turboslag]

Flippin 'eck, £110!! That's insane for a diy amp! My Pioneer SA9100 of around that time was under £100 and was way more sophisticated and powerful!! The diy kit amp that sticks in my mind was the Linsley Hood, a design that is still being cloned now, with pcbs and component sets available on ebay. I did want to build it in period but again, too expensive.

[@michaeldranfield7140]

The first Lindsday Hood amplifiers appeared in Wireless world, I have some copies now but not a magazine I ever bought myself , I just to look at them in the library as a kid but full of complicated maths I didn't understand .

[@turboslag]

@@michaeldranfield7140 Yes, the first or one of the first was a class A design, then came the high power class AB. I loved Wireless World, although I admit I didn't have the maths ability to fully understand the more complex projects. Some years ago I was given a huge collection of full years of WW, from the 60s to 80s, love to sit flicking through those, it's like going back in time!

[@mikepanchaud1]

I built the 80 Watt Linsley Hood from a kit featured in ETI in 1993. BTW, that World Radio History website is amazing, they also have Practical Mechanics going back to around 1903!

[@turboslag]

@@mikepanchaud1 Interesting, do you still have it?

[@mikepanchaud1]

@turboslag Yes , it's currently semi retired, but was in almost daily use until a year ago for watching tv mostly. Faultless service since 1993! I now use a refurbished Quad 303 power amp for tv and music mostly from a Raspberry Pi 400.

[@truthreigns7]

Do they still publish the Practical wireless magazine

[@mistermikeanson]

They do, but it is now more heavily focussed on amateur radio.

[@truthreigns7]

@@mistermikeanson okay thank you

[@truthreigns7]

@@mistermikeanson do you happen to know their website address

[@michaeldranfield7140]

Yes they do but what a load of rubbish it is ,might as well be called practical radio amateur for what's in it now , I stopped buying it over 10 years ago , its not the magazine it use to be .

[@truthreigns7]

@@michaeldranfield7140 ok thank you

[@ashleycox432]

Your collection of stuff is a real treasure trove. I know there's been a few over the years but I'd like to see more videos just going around and taking a look at random interesting things. Do you ever plan to properly shelve / display the magazines all and put it in order?

[@michaeldranfield7140]

I would love to get all my magazines in order but probley wont live long enough I have so many and even if I did don't have enough wall space to shelve everything .

[@andygozzo72]

surely better to use a filament bulb in series with mains as current limiter, they'll self limit automatically, and instantly indicate if theres any issues, without any blow ups, with a variac you can still get a sudden high current draw fault, i always use a bulb limiter with vintage radios and tvs

[@steve83803]

I do wonder what the soldering would be like using the lead free stuff we are forced to use today, fortunately I still have some military graded leaded. The toroidal transformer shows the quality.

[@michaeldranfield7140]

military and medical are exempt from using lead free solder, they know what trouble it causes .

[@steve83803]

Michael you never bought those nice folders being sold at the time for the magazines to keep them pristine and filed by years ? 😀

[@michaeldranfield7140]

No , they never interested me back then .

[@gerryeneral4609]

That’s @ £700 in today’s hard earned!

[@michaeldranfield7140]

That's why I don't think many kits of these will have been sold .

[@bob-s-bit-s]

hi there was some A/V game made in low numbers there used to be kits you could buy back in the day there was reel to reel decks as kits and the same with recorder players maplin used to sell alot of kits you could do

[@michaeldranfield7140]

Yes I have a few Maplin magazines myself , I liked there kits with the ready made pcb , far better than I could make at the time .

[@leetucker9938]

wow , monster capacitors

[@michaeldranfield7140]

Expensive to buy now from RS .

[@truthreigns7]

I never figured you as a heavy metal person.

[@michaeldranfield7140]

I'm not , I'm into Punk , always have been but I also like heavy metal .

[@truthreigns7]

@@michaeldranfield7140 I see

[@peterbell4662]

Ihave one I built from kit

[@michaeldranfield7140]

Nice , that's at least two still in circulation then .

[@stephnieukjones7052]

hi Michael ive probably got caps looks like 47uf 63v they will be second hand but in good condition or a close match as ive got a few vintage amps here if you want i can send you my email address . i was a tv engineer in the 80s but moved over to repairing audio gear as well as djing . stil have the hobby electronics magazines and also the television magazines from the 90s

[@michaeldranfield7140]

I remember the HE magazine was a spin off from ETI , Electronics today international , I do have the odd few HE magazines knocking about but it was not a magazine that excited me too much in the 80 s , the caps are more likely to be 4700 uf at 63v , you can e mail me but for some reason I cant reply to G mail addresses, going to have to get someone who knows about computers to sort it .