A dynamo with field coils can generate either polarity (in the same way a brushed motor with field coils can run on DC or AC). What it does generate depends on the residual magnetism in the coil ironwork. 'Flashing' the coils is a way to generate some new opposite residual magnetism
It all works.
Really? I suppose a bulb failing comes under poor Lucas electrics. After all you never see a US etc car with a light out...
Why not just walk if it's that dark?
When transistorized equipment became common - ie after NPN types arrived - that was negative ground. And only really some UK cars were positive ground anyway.
You must be one of the very few that did this. And even rarer to have a positive ground only radio. Most of the early transistor ones could be configured for either. And older valve radios didn't care.
In message , "Dave Plowman (News)" writes
Interesting. It was 40+ years ago, so I suppose I assumed the radio would be +ve earth only, as it had been removed from a +ve earth car, which would have been 105E or MkIII Zephyr, from memory. I certainly had valve radios, but whether that particular one was valve, I don't remember. I do remember waiting for valve radios to warm up, and also the horror of making a balls up when drilling a hole for the aerial.
Original transistor radios were Germanium PNP technology. That suited positive earth.
But as soon as silicon NPN technology arrived, (ar9ound 1970 really) that was really the death knell for it.
Bit earlier I think. Texas Instruments stopped manufacture of a Germanium transistor we used for logic gates ??302 and we shifted to Newmarket Transistors NKT218. Not certain of the dates but around the end of my apprenticeship:-) 1964? Eventually we were forced to use NPN but I/Cs came along and the rest is history.
It certainly was a nerve wrenching job - drilling an aerial hole in your latest pride and joy. I recall doing it on a car and finding there wasn't enough clearance under the hole for the fully retractive aerial I had bought.
Not sure about car maker's branded radios, but of course in those days most were aftermarket - Motorola and Radiomobile being the common ones in the UK. And at least some of those had internal straps which were soldered for positive or negative ground. BlueSpot had a sort of plug in strip accessible from outside the case which you just turned round, so very easy to change.
Some of the very first 'transistor' car radios were hybrids. Low voltage valves for the RF side, and transistors just for the power amp. So no noisy vibrator - and very quick warm up.
The impressive thing about older car radios was the push button tuning. A triumph of engineering over design. ;-)
Or a mates pride and joy, his first car bought without taking any advice from some back street dealer with a gold tooth and greasy hair.
Mk2 escort looked immaculate , I drilled a small pilot hole in the wing top and immediately got suspicious as it wasn't metal spiraling from the drill, changed to a starret hole saw started drilling and put on a little pressure at which point about a 15"x2" section of filler and newspaper fell into the wheel arch. Got a magnet and the sills were not much better. God knows where it had been used or kept as was only just over 3 years old. The dealer wasn't particularly cooperative at first about either repairing properly or refunding but 6 or so twenty year olds with time on their hands covering a few Saturdays and Sundays on a shift basis drawing attention to the now not immaculate Escort parked adjacent to his forecourt killed his trade enough that he changed his tune.
G.Harman
Can't tell if you mean that as a compliment or a criticism,
In that era unless you lived nearish to the Thames Estuary between 64 and 67 four or five buttons was probably enough for the stations available and easier to use than tuning knob in those days long before controls near or on the steering wheel were available.
G.Harman
I live in Hull and in 1970 I could pull in Radio Luxembourg, Radio Tirana, Radio Moscow, Radio Sweden, AFN Frankfurt, Radio Nordsee Intl, Caroline, Radio Finland, BBC WS and Hilversum 3 all on MW AM.
And that's without the US stations every 10kHz all winter.
All string and springs. ;-)
Chris
Used to have a Rigonda Symphony. Lovely thing with automatic tuning via a large flywheel and motor drive on the tuning knob.
I dont mean 'the date of the first silicon transistor. but 'the date at which most car radios used silicon not germanium'.
I was building germanium radios and amps up till around 1970, after that I never designed for germanium again.
And most of the stuff in the shops switched too.
Some were not. IIRC different coils for each station..
In message , "Dave Plowman (News)" writes
Loved 'em! At least there was no doubt involved. Good, solid things. I hate modern car radios. With an old one, I could do it all by touch, or feel. Now, I have to look. Doubtless the new ones do far more, but really, what do you need? Simple station selection, volume and perhaps tone. Anything else is marketing fluff.
Car stereos are notorious for how terrible their UIs are, and then people go and emulate them for media players ...
Well, if you were to restrict the number of presets to the 5 or so you got with the mechanical system, you could use larger buttons.
But then the average modern radio has many more controls - balance, treble bass etc that you didn't have on a simple mono one. Let alone things like traffic info and so on. Before you even consider a CD etc player.
IMO the worst thing on a consumer electronics interface is the 'mode' button that replaced the slider switch. Car radios have them lots (short of space) and mother (and me) is regularly flummoxed.
Press once for FM1, then again for FM2 (two sets of stored presents), again for AM then cycle back. For visual feedback, some display is required - either LCD or LEDs. It's unreadable :(
Then there is function replacement and interlock - some of the remaining buttons are either non-functional or reassigned to something else whilst in the particular selection mode. Cause of madness.
To get back to normality requires studying the instruction book whilst also overtaking difficult motorway traffic, as the volume has suddenly gone full blast, the knob is now reassigned to changing something else, power off doesn't work, it looks like a traffic officer is somewhere behind, and I'm Jason Bourne with a dozen other things on my mind.
Kenwood make some appalling UI car stereos. Total marketing fluff.
I've got a bottom of the range set that has a well complicated parametric equalizer arrangement instead of simple bass and treble. It's for the kids with reversed baseball caps. I only needed that particular set (KDC-4551U) for the iPhone connectivity - and one day it will probably get replaced with a Raspberry-Pi with Bluetooth.
In message , Graeme writes
AOL mine was under the drivers seat. (no space elsewhere) Push button tuning between the legs:-)
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