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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 29th Mar 2011, 8:10 am   #1
Trevor
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Default Sinclair Z12

I am sure most of us can remember the brave new world as promised to us by Sir Clive!
One of his offerings was the Z12 I can remember saving my paper round money and purchasing one of these
Do any of you have any stories relating to this module?
I have obtained a few of these and will shortly post my intepretation of the circuit, it's a liitle minamilist re stability etc!
regards For now Trev
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Old 29th Mar 2011, 10:46 am   #2
dave walsh
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Default Re: Sinclair Z12

Hi Trevor. I happen to have some paperwork on this including a set of Super IC-12 Temporary instructions with circuit and wiring diagrams. I had to return my unit three times over the period Oct to Nov 1971 accompanied by increasingly bitter correspondence but to be fair, I did get a lot of feed back from the Company [as well as the IC ] which more or less settled down in the end, after some caps had been replaced or rewired. On 1/12/71 my job No is 23579 but I don't know if that reflects sales? I'm complaining at this point that I've spent 7 overall. Despite the difficulty experienced, I recall that I wanted it to work, not get a refund. It's hard to explain in today's world how attractive the prospect of an amp in one IC seemed [now the novelty is in a valve amp]. As I recall, I did run it for some time as one channel in an early stereo setup ie SP25 deck/ceramic cartridge/cabinets home made and speakers salvaged from a scrap PA system. The other channel? Via my tape recorder in amp mode! I would think that Mr Tedechi, the Sinclair, expert over in Brighton, should be a good source of info. Hope this helps you.
Dave W
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Old 29th Mar 2011, 11:30 am   #3
Herald1360
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Default Re: Sinclair Z12

Some confusion here I think..... the Z12 was a discrete amp module with a couple of TO3s as output, the IC12 was ISTR a rebadged Texas audio IC.
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Old 29th Mar 2011, 12:27 pm   #4
dave walsh
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Default Re: Sinclair Z12

Yes you're right Herald. Sorry about that Trev.

I never saw the Z12 but no doubt there's plenty to be said about both products.

Dave W
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Old 29th Mar 2011, 12:34 pm   #5
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Default Re: Sinclair Z12

You're correct Herald. The IC12 was a Texas reject re badged as the Sinclair IC12.

I was a schoolboy at the time and saveD up for a pair of these. One spontaneously combusted due to internal oscillations... And yes I did fit substantial heat sinks!

Bob W
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Old 29th Mar 2011, 3:04 pm   #6
roffe
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Default Re: Sinclair Z12

I have a Antex leaflet with schematics and instructions for the Z12.
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Old 29th Mar 2011, 3:25 pm   #7
gingpeakin
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Default Re: Sinclair Z12

I had one of these. It was the most powerful amp I'd ever had - I was 10 at the time I think. I used it with the great big speaker that I'd pulled from an old floorstanding TV. It was a Pye something and I put the whole lot in the cardboard box from a 'continental quilt'. Duvets were a later name. It blew up in the end of course like most other Sinclair stuff. I still have a Project 60 set with tuner and active fiilter which worked last time I tried it. Did have a pair of Q16s but they blew up as well.

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Old 29th Mar 2011, 5:24 pm   #8
P.Pilcher
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Default Re: Sinclair Z12

Not being a fan of Sir Clive's circuits I satisfied myself with a pair of Dinsdale designed 10 watt amplifiers using OC28's in those days. However one of my fellow electronics university students was facinated with the switching circuitry used in these Sinclair amps and acquired a pair. He managed to get them to work and a few days later was talking to a neighbour to the digs where he lodged. She complained that her radio wasn't working well and asked if he could have a look at it. He found nothing wrong, but learned that the problem was intermittent severe interference. Further enquiry revealed that the periods of this interference coincided precisely with the times he used his Sinclair amps! Needless to say, said amps were rapidly withdrawn from service!

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Old 29th Mar 2011, 6:26 pm   #9
spontaflex
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Default Re: Sinclair Z12

From memory I think it was the X10 that was a PWM switching amp not the Z12.

Geoff
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Old 29th Mar 2011, 6:50 pm   #10
ParcGwyn
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Default Re: Sinclair Z12

My father bought a Sinclair Z12 and was going to clone it and make a stereo amplifier, but in the end he used a Mullard 10W design with OC28s as output transistors and I think OC16s as drivers. He still has the Z12 unused and I copied the circuit diagram down a few months ago with the intention of building a pair when I have time.


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Old 29th Mar 2011, 6:54 pm   #11
Trevor
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Default Re: Sinclair Z12

I have made my own diagram but I find points a bit wierd and would be gratefull if any one could post the circuit!
I also remember playing with my first Z12 but can not remembr what happened to it
regards trev
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Old 29th Mar 2011, 7:16 pm   #12
Trevor
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Default Re: Sinclair Z12

Please find attached a crude sketch of the circuit to the Z12
I am not to sure I have got it correctly so would like a comparison schematic
it is a really crude affair re no emitter resistors on the output devices
Under biased on the output devices
No bootstrap on the main voltage amplifier
the heat-sinking also leaves a lot to be desired all in all a shocker
however i remember it sounding not to bad
all comments welcome
regards trev
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Old 29th Mar 2011, 7:36 pm   #13
roffe
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Default Re: Sinclair Z12

Here's the schematic.The component values for the amplifier are not given in the leaflet(!),only for the tone controls and the preamp.....
The values are my own,noted a long time ago when I had a Z12.
C5 is 1000uF.
More tomorrow.
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Old 29th Mar 2011, 7:41 pm   #14
Trevor
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Default Re: Sinclair Z12

Roff
Thank you very much I can see my circuit is the same once again you have provided a good comparison !Do you have any memories of using your Z12? Please advise as I am interested in the social history as well as the technical
The only reason I do this is so that the information will get onto the internet and these things do not get forgotten
best regards Trevor
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Old 30th Mar 2011, 3:13 pm   #15
toshiba tony
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Default Re: Sinclair Z12

as some of you pointed out, the z12?, not doubting anyone but i dont remember it, ic12 yes, memory usually ok, i think the ic12 used an s776013nd, and thats without research, prob wrong though, anyone?
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Old 30th Mar 2011, 4:17 pm   #16
Herald1360
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Default Re: Sinclair Z12

ISTR SN76013, this looks familiar:

http://www.cricklewoodelectronics.co...2&cat=0&page=1
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Old 30th Mar 2011, 7:50 pm   #17
tonyharker
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Default Re: Sinclair Z12

If anyone is interested Ive got a scan of the original manual (without values) for the Z12.
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Old 30th Mar 2011, 8:34 pm   #18
roffe
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Default Re: Sinclair Z12

Trevor,I'm sorry but I have no special memories of the Z12,other than that I got sound out of it.I only had one single amp,so no stereo.I still should have it somewhere,but you know how it is...
To me these old,simple amplifiers are much more interesting than any japanese monster from the 70's!
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Old 30th Mar 2011, 9:50 pm   #19
Lucien Nunes
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Default Re: Sinclair Z12

I have a pair of Z12s that I got second hand with a Stereo 25 preamp. They're not quite identical, one had Lemco electrolytics and the other unbranded, one PCB brown and one black, the transistors were slightly different too. My first challenge was to make them work, which involved changing a few bits; unfortunately this resulted in a couple of tracks peeling off the PCB. Attempts to reinforce suspect sections caused the PCB to curl up. Maybe the board material was substandard too.

Once they were 'working', I decided to assemble them with the preamp into a compact, Sinclair-sized box to use on the boat, because they would run directly from 13V DC. I modified a Japanese HiFi tuner to do likewise, and set about finding a suitable pair of speakers. The next time I powered the Z12s up, at least one transistor was bad...

At this point they were demoted to the status of curiosities rather than amplifiers and have remained as such, although I did eventually repair the faulty module and have powered them up not so long ago.

Z12 advantages: Size
Z12 disadvantages: Performance, Reliability
A feature-set shared by many other Sinclair products!

Yes I love Sinclair stuff, amplifiers that oscillate and computers that overheat, calculators that give wrong answers, it's all part of the fun.

Lucien
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Old 30th Mar 2011, 10:10 pm   #20
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Default Re: Sinclair Z12

Hi, for all things Sinclair, including audio and calculators as well as the more well known home computers, see this website:

http://www.nvg.ntnu.no/sinclair/contents.htm

On this site you can find some of the original adverts for the Sinclair products, it seems Sir Clive 'slightly over exaggerated' the specs and performance figures for some of his products, allegedly.

I have posted this link before, elsewhere on the forum, but on an unrelated subject matter.

Cheers,
Baz
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