Indeed. I was generalising. But PNP transistors were the norm with geranium in the same way as NPN is the norm with silicon. If you look at a catalogue from the '60s you'll see that NPN were rare and expensive.
That says much about their performance. ;-)
Cars use the chassis as one leg of the supply. So anything which had peripherals - like injection etc - would have to use fully insulated sensors with wired returns.
Thank you all very much. The consensus appears to be 12 volt Positive earth.
I appreciate the response. I am in USA and have wanted a pre war Rover
10 or 12 for years. Having seen one advertised (in the UK) I was interested in some of the details I had not explored before before I took the plunge abnd contacted the sellerThanks a lot
Looking for something completeyly different I came across this in "Automobile Electrical Maintenance" published in 1938.
----------------------- Positive Earthing
Hitherto it has been the custom in single-pole systems to earth the negative pole of the battery to the chassis frame. More recently, however, it has become the practice to earth the positive terminal since there are certain advantages in the latter method. In the first place the h.t. distributor arm of the ignition unit becomes negative to the distributor contacts so that it does not burn away as before. Secondly, the central electrode of the sparking plug is now negative to the metal shell of the plug, so that any corrosion, or burning away, is now confined to the metal shell and not to the central electrode. Another advantage lies in the relatively lower temperature of the central electrode, whereby a lower "high tension" voltage can be employed to produce the spark.
----------------- I understand some of the reasoning but not the bit about lower voltage.
Malcolm
I suppose it means if there's less erosion you don't need as high a voltage to cope with an increased gap - or that resistance increases with temperature. But a bit tenuous.
I've a feeling that the above article misses out that positive earth increases body corrosion for the reasons given.
ISTR that the issue of body corrosion due to polarity was not generally recognised in the thirties; it was only some years after the war that it was confirmed as an issue and the general move back to negative earth occurred.
Of course, BMC took a novel approach by fitting sacrificial anodes. They called them doorhandles.
GMacK
The Rover 10, 12 & 16hp saloons & sports were 12volt positive earth according to wiring diagrams which I have.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Roger saying something like:
Istr reading that the very first production models were presented to selected 'winners' of a lottery (fixed, I've no doubt) in various local ceremonies held througout the Reich, as an incentive for the workers to keep putting money into the VW pot. Of course, such events were thoroughly covered by Joe Goebbels at the time and the cars were taken back as soon as the cameras left, to be 'presented' to the next lucky winner, on the promise that as soon as production really got going they'd get a new car - real soon now.
There was some sort of workers' fund set up to produce the Beetle and if the war hadn't happened the production VWs would have been filling the streets, driven by grinning family men as they drove their flaxen-headed Hans and Heidis to Youth Camp.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Geoff Mackenzie" saying something like:
Or subframes.
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