Charging a car battery

I remember driving a car where the alternator was not charging the battery, as the journey went on "it" kept dropping services[1] until finally the car conked out alltogether. From first symptoms to conking out was twenty~thirty minutes minutes (ten or so miles). Livingston going back to Edinburgh, knew there was a problem but wanted to get son(special needs) home or at least as close as possible.

Yes. But that has been replaced by all the other things that take power at all times. Maybe only a small amount each - but it adds up.

Of course - if left on after the battery is fully charged. But that wasn't the question.

Have you asked the maker how long you can leave the car and guaranteed it will start - assuming a good condition fully charged battery?

Sounds similar to the 14 quid Lidl one - except a lower peak output. The Lidl one will charge an average battery overnight - then switch to maintenance mode. Which is a lot lower than 13.8v. Can't remember the exact figure - I'll try and check tomorrow.

However, 13.8v is what both my cars runs at when the battery is fully charged. Which might be high for a constant trickle charge while parked up

- but obviously not when in use.

Sounds like you've checked a poor battery. A good one will give you very close to the figures I gave. But of course does depend what you take as the terminal voltage before stopping.

The battery capacity figure is arrived at using the 20 hour rate - so a higher discharge.

A decent one had a very clever push button system which did just the same job as a station memory. But must have cost a fortune to make.

The were hybrid ones which used a transistor power amp and 12v HT for the RF valves. Getting rid of that irritating vibrator.

First thing that showed on one of mine when the alternator failed - no warning light came on - was the auto going into limp home mode and staying in 3rd gear.

Since I was on my way to an important work thingie, the AA (after it finally stopped) would only take it to an appointed garage since I wasn't going with it. If I had, they'd have taken it and me home.

That bastard garage fitted a full price genuine makers new alternator and a new battery too. The bill was enormous.

They used inductors rather than the capacitor for tuning. I always assumed it was to prevent microphonic effects due to the vibration on the thin vanes.

Capacitance could be varied plunger style also, as indeed it was in

A capacitor would be more liable to drift or modulation due to side to side motion, whereas an inductor would have to move longitudinally, not a possibility with a stiff wire/ rod coupling to the pushbutton.

It's supposition really, but I cannot think of any other logical reason for using the inductor to tune.

Yes I remember some of the write ups a few years after, "if we hadn't discovered transistors, what wonders would valve technology have brought to us?"

AB

Put the charger on a plug in timer set for say a half/quarter hour per day.

I think mine was a good bit less than that...

.....but not that cheap :-/

I looked out for the Lidl ones but they weren't about when I needed one :-(

In message , Archibald Tarquin Blenkinsopp writes

I believe (though possibly incorrectly) that the advantage of inductor tuning makes it easier to accommodate the capacitance of the aerial coax at HF end of MW and LW. It also avoids the inevitable capacitive 'pot-down', and increases the sensitivity at the HF end.

I don't understand. It's a long time since I played with wireless, but surely the cable capacitance isn't a factor. Whether the final matching is done by L or C, the coax is just a fixed impedance?

I recollect that there used to be trimmers and padders in the tuned circuits, but these were to maintain "tracking" between the higher frequency mixer oscillator and the aerial tank circuit.

I cannot see that this system of tracking would alter even if the inductor became the new variable.

The sensitivity would be poor if the tracking were out, as the RF tank circuit would no longer be at maximum output when set to a station 470 kHz away from the mixer.

The term "pot down" means nothing to me, but it is a long while.....

I tried a quick search, but couldn't find anything. Could you enlighten?

Sadly a lot of the brain cells that accompanied me on my journey through consumer electronics are now ossified :-(

Regards

AB

those tuners were standard in B&W TVs for a long time. Not a turret tuner, I can't remember the name. OK until there are more radio stations, then you wish for a simple knob.

That's what mine is, a basic 1 transistor class A amp.

NT

Yup. An OC35 on a heatsink will do about 5W class A with an output transformer as 'load'

This was a sort of copy of an EL84 single valve class A amp -Very popular in small audio kit back in the day.

It took really a lot of transformer to do push pull before NPN transistors came along, and then of course no transformers at all became the norm...

There is zero need to charge it every day. Once a week would be more than enough. With a charger which either switches off when fully charged, or goes to a maintenance mode.

Same as all Lidl tools, you have to buy when on offer. And depending on the store/item can sell out very quickly.

The process of evolution was the development of valves that would work with an HT of only 12 volts, rather than the normal

The only thing that wouldn't work @ 12V was the output valve which drove the loudspeaker but, by this time, power transistors capable of doing the job had been developed so one of those was used to drive the loudspeaker instead.

So the word Transistor (in the singular, as you posted, was

The first TV that PYE sold claiming to be 'transistorised' had one transistor - used as sync separator, IIRC - but everything else remained valve driven. You might call that a sales gimmick - and you would be right - but the car radio was a genuine way of operating a car radio from 12V without any complicated high voltage generation required and was a real advance.

The first amplifier I built *was* an EL84 class A amp, although I did have a preamp stage too. In fact, there were two...it was stereo!