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Bosch dynamo fitted to an A7

Does anyone have experience of running the John Gardner/Dave Lindsley solid state 12 Volt converter with a modified Bosch dynamo fitted in an A7?
Many years ago I converted some Bosch (ex Beetle) dynamos to run in A7s. They happily churn out 45 Watts at 6 volts so there's plenty of current available for good lighting etc. However, there are good reasons for running with a 12v system and I would now like to convert my (Bosch) dynamo to give 12 volts. Again, some time ago, I fitted the above solid state converter to a friend's car but found it would not run with a modified Bosch unit and so the usual Lucas one had to be used.
I never investigated the reasons for my lack of success so would welcome any input on this topic. The principles of the device are well set out in the A7 Companion, but I would like to know how sensitive it is to variations in the resistance of the armature and field of the dynamo. Also, what is regarded as the maximum working electrical load.
Hope someone out there has "been there and done it" and can pass on some useful info!!
Ron

Re: Bosch dynamo fitted to an A7

Correction to previous entry. The Dynamo churns out 45 amps. Thought I ought to get that one in quick!!
Ron

Re: Bosch dynamo fitted to an A7

Hello Ron,
Have a look at the following site:

http://mgaguru.com/mgtech/electric/et231.htm

I think the answer lies there.

Wouldn't the simplest way of going 12v be to get a 12v VW Dynamo and Regulator, or are they different to the 6v types?

I have a 6v set up with the VW mod on my chummy which seems to work perfectly, but I am considering going 12v on another car I have.

I think that "down under" anyway, 6v VW dynamos would be almost as rare as A7 ones.

Regards

Barry R

Re: Re: Bosch dynamo fitted to an A7

Hello Barry,
Many thanks for your input, much appreciated. Sadly the post 1967 12V Bosch unit is too large to allow the "usual" conversion to fit it in a later A7. Pre '67 all except a very small number of Beetles were 6V as Standard and this is the one I have used. The very rare 12V unit, with the same dimensions as the 6V one was, I believe used in Police cars. If only I could find one!
The mgaguru site is very interesting. It confirms the importance of controlling the field current. A 6V set-up won't like having 12V dropped across it! The 6V Bosch regulator has a resistor in series with the connection to ground. Perhaps part of the answer lies in robbing this resistor from a couple of regulators and putting the two in series to protect the field windings and then using some other means of controlling the output to a nominal 12V.
Anyone out there with more ideas/info?
Ron

Re: Bosch dynamo fitted to an A7

Ron,
are you looking for more reliability by using a VW dynamo or more output? If you are simply wanting more output the use a 12v cut-out of the same design as the 6v version that was originally on your A7, change the battery to 12v and the bulbs etc. and you have a 12v system on your A7 which in a like for like situation ( watts used in 6v against same watts used in 12v ) you are only taking HALF the current from the dynamo.

I have been using this system for some years now without any problems, unless you think buying cheaper bulbs, over the counter anywhere, is a problem?

The other beauty of the system is that if you have a mechanical failure in the dynamo and of the later style A7 dynamos off of a 6v car will work without any modification ( other than moving the third brush to reduce the output )

Re: Re: Bosch dynamo fitted to an A7

I have heard of this being done, and also variations, eg using a modern simple 12v cut out and tucking it away somewhere, and also using a later type Lucas Regulator (RB106 or similar) and eschewing the third brush to give automatic control. But wouldn't all such conversions mean that higher engine revs would be required for "cut in" to take place, or am I not thinking straight? I have a VW 6v conversion on my car, and whilst it works well and seems reliable, my only compaint with that system is that there is very little output at lower engine revs.

I would like to try 12v on another Chummy I have and being a worrier, am trying to chew over all the pros and cons before I do anything.

Regards
Barry R

Re: Bosch dynamo fitted to an A7

Yes Barry you are right, the engine has to rev faster before you get a charge from the dynamo at 12v but you are talking about the equivalent of about 10 mph in top gear and not many drive their cars as slow as this. The benefits certainly out weigh this 'disadvantage' if you can call it that, in practice you don't even notice it.

On the plus side the starter motor turns the engine over in a similar fashion to a modern car making starting easier and quicker.

I have a friend who has used a more modern two bobbin cut-out with voltage regulator and a two brush dynamo conversion but he has found that the regulator contacts burn out fairly quickly as the are having to work quite hard.

Re: Re: Bosch dynamo fitted to an A7

Hello Malcolm and thanks for your response.
I have already tried to respond to your reply but something has gone wrong. So if you end up with two similar replies, please ignore one.

I will have to try and work out what engine revs 10mph in top gear represents, but I would be very satisfied with a reasonable dynamo output at that speed. It looks as though I will have to have a look at my set up (6v VW Dynamo with Bosch Cutout and reg.) I don't get any charge until about 25 mph in top gear. 2nd gear, there appears to be enough revs for reasonable charge at "procession" speed, and there is a fair amount of 2nd gear work around here as there are plenty of hills. But I worry about top gear motoring, as I am now convinced my set up is "sluggish" as far as commencing to charge.

On the matter of the more modern two brush conversion and two bobbin regulator on 12 v., I can understand the stress the regulator contacts would be under, as the field coild would be carrying a fair current with 12v output.

Thinking about that though, if my 50 odd years old memories are correct, more turns of finer wire would give more resistance, therefore less current, but could be arranged for same "ampere turns" so same magnetic energisation of the "field"

I need to talk to someone skilled in these black arts.
I can't see that it should be a very complicated matter to get some more appropriate Field Coils wound.

Shouldn't be that expensive either.

I will have a look and see what I can dig up.

Somewhere I should have some typical data on what nominal field currents are specified for Lucas Dynamos. That would be a starting point anyway.


Kindest regards,

Barry R

Re: Re: Re: Bosch dynamo fitted to an A7

Thanks for the contributions Malcolm and Barry. Answering Malcolm's question: I just felt I ought to at last check out whether the solid state converter used by many to get the most out of the Lucas dynamo, had been sucessfully used with the Bosch conversion. You remember I had had no luck when trying it on an A7 belonging to a pal of mine. My unit has worked fine since I built it (and many others) some 12 or more years ago. But to have 12V would be nice, so time to check again via this forum.
It is true that higher engine speeds are needed to get a charge. I would say you need about 15 mph or more in top, but that's no problem you'd need to drop a gear soon anyway.
Unless you have reversed the residual magnetism in the field casing (which is something on my "to do" list) there will sometimes be a reluctance for the cut-out to pull in when first starting up. This generally only applies after a winter lay-up. If a burst of high revs fails to do the trick you have to dab the cut-out in by hand! Positioning the brushes during the mod is critical. I experimented to find the optimum setting and am happy with the 45amp output.
I know there a few folk who have had success with the simple mod used by Malcolm but I'm curious to know if they are putting 12V directly across the Lucas field windings, as this is a shunt wound unit; or is there a series resistance somewhere to limit the field current to the original value. Hope to hear some more on this topic from some of our gurus out there!
Ron

Re: Re: Re: Re: Bosch dynamo fitted to an A7

I am following this topic with interest recently and have some points......

I have always understood that the Austin Seven has a poor reputation for charging and lights etc. Knowing this I converted to 12V when building the Colander. I calculated the current draw of my lights to be say 7.6A, add to this around 3 amps as a rough figure for the coil when running and you get around 10A ish or thereabouts. My "solid state" conversion states quite clearly that 10A is the max you can pass, so I have set the potentiometer inside to just show a miniscule discharge when running with lights on. given the fact I have a 35Ah battery I should realy be able to run for a very long time without having a problem. Even if I fitted say 55W headlight bulbs this would increase current draw to around 10.8A plus the coil resulting in a discharge around 3A or so when running. The 35Ah battery would last about 10 hours at this rate of discharge.

I can see that around town where revs are down low and you may be idling could cause a problem, but surely on a run you would be OK. So the question is can the dynamo take 10A or so without dying (I believe overheating of the armature is the prob)or is this the reason for the uprating?

Regards

Steve

Re: Re: Re: Re: Re: Bosch dynamo fitted to an A7

Hello again from the Antipodes.

Steve

I will attempt to give my hopefully "reasoned" opinions in response to your post.

I think you have just about hit the nail on the head with all your observations. As I undserstand the original specifications, the Coil Engine Lucas distributor was originally rated as 8 amps maximum output at 6 volts which is 48 watts.

If you are running 10 amps at 12 volts the total output is 96 watts.

It is a testament to the original Lucas construction (despite all the bad press Lucas gets) that these things seem to be able to withstand a 100% overload
70 or so years after they were made!

I know I will be shot down in flames by people who have performed the feat, but I think that a prolonged journey, with the headlights on and the Dynamo being expected to maintain 12v 10 amps output for say 5 or 10 hours is asking a bit much.

As I understand it, the reason for the original brilliantly seized opportunity to latch upon the fortutitous circumstances of the availability of 6v VW Bosch Dynamos was firstly, the fact that they were so constructed that they are good for up to around 45 amps output, secondly that their conversion is a relatively simple operation, thirdly that they were of robust relatively modern construction and spares availablity was and probably still is realtively good.

They also can be fitted with minimal "visual offence" in the car.

The reason that I am at least contemplating upgrade to 12 volts in a Chummy I want to get back on the road is really convenience.

In this far flung outpost of the Empire whilst 6v spares (bulbs etc) can be obtained, they are hard to procure and generally expensive. The sheer onvenience of 12 volts is really what that part is all about. Plus the fact that right now I can't find a 6v Beetle Dynamo.

I am totally satified with my 6v Bosch ex VW set up, apart from the fact that I think it may be a bit "sluggish" in terms of "cutting in" I have not had any real problems apart from the fact that I need to top the battery up occaisionaly with my battery charger. This may just be because most of my runs are short trips around my home "village" but I have not had the same trouble with other cars.

I live in an island which has the large population centres (Hobart and Launceston) separated by a good by "well hilled" highway of some 123 miles distance.

Would I drive my Chummy from Hobart to Launceston? Yes, have done.

Would I drive my Chummy from Hobart to Launceston in hours of darkness? Yes, have done ( with by VW Dynamo doing its stuff)

Would I drive my Chummy from Hobart to Launceston in darkness using a 12 volt conversion on a Lucas Dynamo running at 100% overload? Only if I had a torch and a spare dynamo, and then preferably with a travelling companion who I could coerce to do all the dirty work!

Kindest regards,

Barry R

Re: Re: Re: Re: Re: Re: Bosch dynamo fitted to an A7

Ok, so I have just demonstrated by mathematical incompetence to an international audience.

What I meant to say in my last post was 12v at 8 amps which is 96 watts would be a 100% overload, based on what I think are the original "nominal" ratings for the Lucas Dynamo, and 12v at 10 amps is 120 watts, or something like 150% overload.

Over anything other than short time operation, it would be well to anticipate a bit of solder being flung around inside.

Add this to the fact that when these Dynamos were made, "shellac" type varnishes were the basis of most insulation. Shellac is a natural substance and has a "life" of something like 60 years, after which it is prone to natural decay. So the effects of the additional heat generated in the field windings alone would have to be anticipated to hasten the Dynamo's likely demise.

Regards

Barry R.

Re: Re: Re: Re: Bosch dynamo fitted to an A7

Thanks for your comments Steve. Which solid state converter ase you using? It's some years since I helped fit the John Gardener designed unit to someone elses's car and I don't recall any potentiometer. Is there another source available and is Dave Lindsley still marketing the one most often referred to?
I share Barry's comments both on the original attraction of 45 watts and now the attaction of better 12V lights etc some 20 years on.
However we still await the input from someone who has used a proprietory solid state converter with a Bosch conversion. That was where I came in!
Now the total wattage thing puzzled me for some time until I discovered the article on about page 261 of the 750 Companion. Where had all the extra watts come from without burning out the standard Lucas unit? Well, in summary, the field current stays almost the same and consume 3watts more than its intended 20watts but the cut-out load of 7 watts is avoided and the armature loss, now running at a nominal 12V, is down from 68 watts to 23 watts! Appearently the dynamo now has to cope with only a third of its original heat. We now get the watts in the right place!
I have swapped info with Malcolm Watts and he confirms that on his mod to give 12V he has also limited the current through the field to somewhere near the intended figure. Similarly with the higher voltage across the armature the armature losses are dramatically reduced. Malcolm's solution seams simple, effective and robust. He may yet pen a line!
Ron

Re: Re: Re: Re: Re: Bosch dynamo fitted to an A7

I'd be interested to hear about Malcolms "Watts"!!

Ref the solid state conversion I think it was from the Kirby Wiske guys (Austin Seven Service), although I'l have to dig out the paperwork to confirm?

The potentiometer is to limit the charging current to a sensible figure, you are advised to turn on all electrical items and read the discharge on the ammeter, if more than 10A turn off things till it reads about 10A (mine didnt read that high). You can than rev the engine and turn said potentiometer till it shows between 1A and 0A discharge. In actual fact it is very important to point out that it is the POTENTIAL DIFFERENCE that causes the charge current. i.e if the battery was reading say 12.5V you would put a 1.2V chargin voltage accros it making the voltage across the battery read 13.7V. Because of this if you have a flat battery the charge current/voltage can become ecssesive, which is were the solid state device comes into its own as well as having a fuse to protect it from harm. I believe the solid state device must work by control the field current in someway although am not certain?

I'm going to stick with it and see how I get on, I probably wont do a huge amount of long night journeys anyway!

p.s I admire your bravery in driving to Launceston, which by my reckoning is about 20 miles up the road from me, however I would dispute your mileage and cant find the road you used on my world atlas?

Steve

Re: Re: Re: Re: Re: Re: Bosch dynamo fitted to an A7

This is all certainly very interesting.

I have now found the "Companion" article which I must confess I looked for earlier but could not find. I think there is also some other published info, but can't think where at the moment.

The "Companion" article is good stuff, and is really saying that if we get rid of power wasted in the electromechanical Cut Out, and control the field current electronically to within something like the original field dissipation under 6v conditions, then by halving the current for a given load power requirement using 12v, we can run things cooler and more efficiently. Armature efficiencies at 12v are also acknowledged.

I agree with all that, and in the example given in the two diagrams on p261 of the "Companion" clearly demonstrate the efficiencies available.

But in the examples given, the actual current being delivered by the dynamo is still well within the original 35amp rating of the particular dynamo.

So, I suppose what I am still querying is just what the safe continuous load for a 12v converted A7 Lucas Dynamo can be anticipated to be. I know the system works, and have seen other cars converted.

But I am yet to be convinced that a simple 12v conversion can really enable significantly greater output currents to be safely drawn from the Lucas Dynamo than say 8 to 10 amps, and even at this level I think things must be at least "stressed"

In Steve's example, which I responded to earlier, he was talking about a situation where the Dynamo would presumably be operating at full bore for the period of driving where he was to rely on battery capacity to cope with the difference between load current and dynamo output.

From what I understand to be the situation, the fundamental difference between the Lucas A7 Dynamo and the Bosch VW Dynamo is that in the case of the Lucas set up, the dynamo output is "controlled" at the D+ end of the field coil, whereas in the Bosch set up, the dynamo output is "controlled' at the earthy end of the field coil.

If there is a guru out there who can suggest an electronic control circuit for the Bosch set up then I would love to try it. That would seem to have the potential to provide say, a comfortable 12v 20Amps at least out of a dynamo nominally rated at 45 amps output capacity.

It would seem to be a very satisfactory situation to contemplate a set up which gave all the attractions of a 12v system, and the knowledge that the dynamo was loafing along delivering about half its rated power capacity.

All this new fangled electronics tends to be a bit beyon me, I am definitely a "steam age' electronics man!

I look forward to reading "watt" Malcolm has to say

I wish there was a spell checker!

Kindest regards,

Barry R.

Re: Bosch dynamo fitted to an A7

Barry,

Just dip your toe in the water instead of standing back and you will find my method not only works but is kinder to the dynamo.

It is not Volts that kill dynamos it is the Amps.
If your total wattage with bulbs is approx 90 watts ( 4 x 5 watt bulbs abd 2 x 35 watt headlights ) then you will be drawing 90/6 = 15 amps from your system. By simply changing to 12v with the same wattage lights you are now drawing 90/12 = 7.5 amps.

Current ( Amps ) causes the dynamo to overheat which is why the Lucas dynamo got such a bad press in the 60s and 70s as people moved the third brush around to try and overcome the amps deficit and ended up taking 15 amps from the dynamo in order to prevent discharge with the lights on. Bad move - overheated armature - dynamo failure.

In an attempt to put your mind at rest, my RK saloon ( with a Lucas 35a dynamo ) is a 12 volt system, the only material changes ( other than bulbs and odds and ends ) is a 12v version of the original cut-out, a 12v coil and of course a 12v battery.

The car has done over 4500 miles in the last 12 months, including several long trips ( I live in Cornwall UK and to get to Exeter you travel 100 miles ! ) I have taken the car to Beaulieu, France Longbridge, all long trips and have had absolutely NO CHARGING PROBLEMS. I use 55/60watt Halogen headlights. I can see where I want to go after dark !

A few other factors come into 12v:-
Because the number of AMPS needed from the dynamo is less then the 3rd brush is in a reduced output position and the dynamo runs cooler.
The bulbs are cheaper,
The bulbs give out more light ( a 5w 12v bulb gives more light than a 5w 6v bulb due to the thickness of the element )
I don't need to carry a vast range of spare bulbs, replacements can be bought anywhere,
a 12v battery, code 028, is cheaper than an equivalent 6v battery plus I can pop into Halfords and pick one up off of the shelf.
The engine starts better, not only because of the extra speed of starting revolutions but less of a voltage drop across the coil.
Voltage drop caused by bad electrical joints is less of a problem.
The size and cost of the wiring is less.

A friend of mine ( a retire profesional electronics engineer ) is in the final stages of restoration and he is following my 12v route with the comment, "it seems silly not to ! "

If you get hold of a 12v cut-out why not try it ( some people even use the original 6v cut-out but I would not reccommend it! ), if it doesn't work for you then changing back to 6v is a piece of cake, but I bet once you change to 12v you will not change back!

regards to all doubting Thomases, the proof of the pudding is in the eating!

Re: Re: Bosch dynamo fitted to an A7

Thanks for the further input Malcolm. Just for the record, I ain't one of the doubting Thomases! I well appreciate the volts that are available. When determining the best orientation of the brushes in the Bosch conversion I used the open circuit volts as the parameter when "inching" around the complete brush end of the dynamo in the car. No tie rods, at this stage, just a couple of G clamps. I seem to remember seeing some 35 volts at best position but backed off a bit when it started to smoke!!
If you check through the info in the Companion article, you can see that although a notional 8 or 10 amps is offered by the Lucas unit, there is a total "load" of some 134 watts, suggesting there's over 25 amps wizzing around in the thing. Most of this is simply heating up the dynamo internally. As Malcolm says, at 12V the current in the armature is halved. Its the I squared R product that causes the waste heat.
A final thought (for today anyway!): the earlier dynamos, as fitted to Chummys etc, is not able to breath as well as the later units, so is more prone to overheating when given a high load. I guess there is less scope here for the same, high wattage at 12V than with the later units.
Ron

Re: Re: Re: Bosch dynamo fitted to an A7

Thanks Malcolm,

I am not really a doubting Thomas, as I have seen the practical evidence that this whole thing does work.

But I am a person who was once well trained in electrical engineering and I like to ensure that in whatever I do I work to sound principles.

Anyone who doubts the availability of the extra volts only needs to disconnect the D+ and SH wires of the Dynamo, and strap the terminals together. A voltmeter accross the strapped terminals to earth and a few revs on the engine will amply demonstrate what the unit is capable of developing.

Your example of some 7.5 amps drain I can live with, but I must say that Steve's 10 amps or so still has me worried. If that is sustainable then all I can say is that the original 8 amp rating on the Lucas Dynamo was very conservative indeed.

What I must admit in all this is that I forgot to take into account the Third Brush adjustment which would be required on setting 12v output. The fact that adjustment of the third brush would help reduce otherwise alarming (to me anyway) field current makes the whole thing a little more understandable.

Ron's comments about the "I squared R" considerations are spot on. But if we limit the total current to figures within the current ratings of the Dynamo then all should be fine provided the "I" rating is not exceeded and of course "R" is constant.

I have dug out a 12 volt cut out and think I have a spare "expendable" Lucas Dynamo here. When I can work out a way of setting it all up in the lathe, I will try and do some tests, and will try and actually measure field currents etc.

But, and I think it was Malcolm who pose a question earlier in this thread, it really is a matter of what you want to do.

I buy all Malcolms arguments for the convenience of 12v operation using a Lucas Dynamo.

But if you want to accomodate current drains larger than those originally specified for the Dynamo, which I am still trying to corroberate as being 8 amps but now can't find the figure anywhere, then I think that the VW Bosch set up, with a suitable controller, would give the added bonus of comfortably obtained higher output currents.

Is there anyone who can point me to explanatory material on the workings of the electronic regulators?

A very interesting thread indeed.

Barry R.

Re: Re: Re: Re: Bosch dynamo fitted to an A7

Thanks Barry, You have confirmed that about 8A is sensible for the dynamo, wereas I have about 10Aish being drawn under certain operating conditions. BUT I am willing to live with it and see how it goes because I will not be doing a great deal of night driving. If I did drive a lot at night I could conceivably turn down the charge current slightly via the potentiometer and rely on a well charged battery for a one off journey. Incidentally I have left of the brush cover to try and improve cooling. Has anyone tried modifying the casing for increased cooling?

Given the fact that Malcolm was the chap who advised me of the merits of going 12V , and has proved that over a period of time and miles it works well than we probably dont have much to worry about. The only thing I was trying to figure out with Malcolms excelllent lights(55W) is that by my calculations including an average figure for the coil there must be a current drain of well over 10A. If this is the case then the mileage that Malcolm has done (he is famous for actually using the car!) must show that if well maintained and adjusted perhaps you can just about pull it off, or maybe Malcolm has a very good dynamo with insulation in good cond etc?

At the end of the day we all seem agree that 12V is the cheaper and probably electricaly better way to go if originality is not a major issue. I guess we've all got a slightly different set up that seems to work OK, so we just need someone with the Bosch conversion and an electronic solid state device to answer the original question!!!!

Regards

Steve

p.s Will you be visiting Mikes check up day Malcolm?

Re: Re: Re: Re: Re: Bosch dynamo fitted to an A7

I think that just about sums it up Steve although it's worth stating again that the amps now available for useful work come, in part, from the amps no longer being consumed by the armature and turned into heat. That's why the dynamo is more electrically efficient and doesn't overheat.
Perhaps we can persuade Malcolm to give us a full run-down on his set-up some time.
Ron

Re: Bosch dynamo fitted to an A7

The problem to me seems to be the availability of the Bosch equipement, there's plenty of Lucas stuff about (in relative terms), but have you tried tracking down a Bosch unit.

I'm with Malcolm on this one, keep it simple and should anything go wrong, there's always a spare Lucas unit about.

Namoi

Re: Re: Re: Re: Re: Re: Bosch dynamo fitted to an A7

Thanks gents for a most interestin discussion.

It is amazing how much you can take for granted in these things, and it is not until a question is raised that things which one takes for granted are sometimes as not as obvious as they may at first seem.

I have spent an hour or so thumbing through my copy of the 750 MC Companion for the first time in about 15 years, what a bonza publication that is. Have satisfied myself from it that the rated output of the coil Engine Dynamo is 7.5 to 8 amps and that the field resistance should be somewhere in the vicinity of 2 ohms.

Have found a sparesLucas Dynamo and now only have to work out a safe way of driving it so that I can have a little "play" I think I will probably set it up in my Millimg Machine because I can easily arrange a suitable range of speeds with that.

Have also had a look at the PWA7C " Digest of Technical Articles" which also has some good info.

Distressed to find in it a table of engine revs vs road speed for 3 speed 4.9:1 rear axle Chummy. Distressed because I went to some trouble a day or so ago to calculate them myself! But it was good to confirm that my calculations were OK.

Also found some stuff about the "balance point" for charging with the lights on should be at 30mph in top presumably, and that is probably where it is on my car.

My son has just told me that he has a mate with a whole pile of old VW "junk" and I am going to see if he has a 12 v VW Cut Out/Regulator box and if so see if I can coax my 6v VW Dynamo conversion into spitting out 12v.

Steve, on the subject of "Launceston" I understand that you folk pronounce it "Lonston" or something like that whereas we down under say "Loncestom" or Lawnceston and there are often great arguments about it.

I will let you all know if I can find a suitable circuit for a solid state VW Bosch 12v controller.

Thanks for a very interesting and informative intechange.

Regards,

Barry R.

Re: Re: Bosch dynamo fitted to an A7

Fair point Naomi, the 6V stuff is getting pretty scarce. In part I think this has arisen from the Beetle owners up-grading their pre-67 cars by installing new 12V dynamos and dumping the old 6V unit. That was when I got mine cheap some 20 years ago!
Happily I have three tried and tested Bosch conversions on the shelf (as well as one in the car!). So "No worries" as they say down under - at least for some time.
But where are the gurus who can answer my question at the entry point to this thread?
Ron

Re: Bosch dynamo fitted to an A7

Where are the Guru's, why, out looking for Bosch units......

Phil...

Re: Re: Re: Bosch dynamo fitted to an A7

Hello Ron,
Just to confirm that there is a circuit for an electronic regular on the excellent "Speedex" site. Needs rejigging to make it suitable for positive earth though and I may be able to do that. Seems to be absolutely suited to Bosch type field control.

It's 4am here. My youngest son's wife has just had there first child about 1/2 an hour ago and I am on my way in the the hospital to show "Ava Kate" a picture of the Austin Seven! 6lbs 14oz. Mother and Bub both well, Father will recover.

So will need to follow this thread later.

Barry R.

Re: Re: Re: Re: Bosch dynamo fitted to an A7

Many thanks for remembering the Speedex site Barry. I think that's the nearest we will get to finding a solution and that wraps it up for me for now
Ron.

Re: Re: Bosch dynamo fitted to an A7

Hi,
At risk of trying to grab the last word; I've been following this thread with interest, I run the Speedex site and would like to add more definitive info on electronic regulators. If anybody comes up with a better circuit or one with the opposite polarity I would be interested in posting it for all to use. There do seem a few parties selling little boxes of tricks but when opened up they're all neatly potted in resin and I can't figure out the components!
Thanks for the kind words about the Speedex site, I'm hoping it becomes more active again soon. It's nice to know it's not just me going into it, and being worldwide is a big buzz.

Dave