which uC brand should I use ?

[Nigel Goodwin]

well some people are mad over authenticity when it comes to older cars

Controlling the field coil will not decrease the power

I think you'll find that that's how it works, both originally, and as you're doing it.

the dynamo needs regulating at all times or you can end up with 40 volts (I managed 18 before pulling the plug on it and it looked eager to keep rising)

How?, the battery will stop the voltage rising that far, just as it does on the original regulator, and just as it does for an alternator.

I can set the current limit in the software and it will run to that, so if I have a temp sensor and related algorithm to increse the amperage figure when the weather is cold I can allow more power to be generated in winter but keep it to normal levels in the summer so as to not burn anything out.

You seem a bit confused about what you're doing? - as I said you can't increase the output, only decrease it - and that's what the original regulator did. No need, and no point, in monitoring ambient temperature - you charge the battery until it's full, then drop charging current to a low level to keep it topped up - same winter or summer.

I suppose I could just replicate the "burst fire" control of the original and run at a high clock speed, at the end of the day it still results in a crude PWM but with a drift in frequency, in his case this was 70-150 Hz hence my choice of frequency. in any case once built I can use both versions of control, thats the beauty of the uC method I get to play with variables without unsoldering stuff all the time, or redesigning the whole project.

as it happens i got a more steady regulation than the original reg, so I did something right

Why did you want a more steady regulation?, what advantage does it give?.

 

[Thunderchild]

I think you'll find that that's how it works, both originally, and as you're doing it.



How?, the battery will stop the voltage rising that far, just as it does on the original regulator, and just as it does for an alternator.

When your battery is being subjected to 18 volts (I got it that high using a test bed made up of an underpowered motor rigged to a dynamo) the battery will soon dry up and you will have some "interesting" results

You seem a bit confused about what you're doing? - as I said you can't increase the output, only decrease it - and that's what the original regulator did. No need, and no point, in monitoring ambient temperature - you charge the battery until it's full, then drop charging current to a low level to keep it topped up - same winter or summer.

if the engine speed is high enough you will get more than the rated current from it, I was able to set how much current I wanted at will and easily got 20 amps out of the 20 amp alternator, I'd easily get more in fact when i blew the prototype (pcb track fell apart due to my poor build of a first PCB) it peacked at 30 amps at which point the voltage became so high on the mosfet gate it blew, the regulators are set for 13.5ish volts so no harm in taking it to 14-14.5 volts more current would easily flow

Why did you want a more steady regulation?, what advantage does it give?.

wasn't particularly after a steady regulation it just occured that way, probably due to the lack of (or insignificant) hysteresis in my circuit that the original reg will have, the only time mine was not pretty steady and much like the original was when it was taking too long in playing catchup with the engine speed

 

[Nigel Goodwin]

When your battery is being subjected to 18 volts (I got it that high using a test bed made up of an underpowered motor rigged to a dynamo) the battery will soon dry up and you will have some "interesting" results

There won't be '18V', the battery will absorb the current and maintain the voltage across itself - it's how battery charging works. An alternator will put out a LOT more than 13.8V, I would imagine getting up towards 100V?. I remember years back, I kickstarted my motorbike and the battery lead fell off, the output from the alternator blew all my bulbs

Even worse I had to walk back home, having no working lights!.

if the engine speed is high enough you will get more than the rated current from it, I was able to set how much current I wanted at will and easily got 20 amps out of the 20 amp alternator, I'd easily get more in fact when i blew the prototype (pcb track fell apart due to my poor build of a first PCB) it peacked at 30 amps at which point the voltage became so high on the mosfet gate it blew, the regulators are set for 13.5ish volts so no harm in taking it to 14-14.5 volts more current would easily flow

If the battery is flat, you WANT that current going in the battery, if it's fully charged you turn off the field coil and lose almost all of the charging current from the dynamo.

Power out of the dynamo is proportional to field current, which is why a regulator controls the field current. But as I said, you can't INCREASE power, only decrease it.

wasn't particularly after a steady regulation it just occured that way, probably due to the lack of (or insignificant) hysteresis in my circuit that the original reg will have, the only time mine was not pretty steady and much like the original was when it was taking too long in playing catchup with the engine speed

An electronic solution is likely to be more stable, crude mechanical systems work fine though, as stability isn't an issue.

 

[Thunderchild]

well I got my battery to hit 18 volts ! I think it was fully chrged so just could not take it anymore

if the battery is flat I do need all the current I can get and can get it but a flat battery can go down quit low like 7 volts (we did it on my friends car with all the testing we did) so with a voltage difference of 6.5 volts the charge current can be very high and high enough to burn the dynamo out so current regulation is also implemented to prevent a literal meltdown, in cold weaher i can allow that to be a bit more current but must stop things overheating

I think the hysteresis in the old reg was due to the voltage being sampled off the battery so there was a delay in rise and fall of voltage, I am taking the measurements from the dynamo itself

 

[Nigel Goodwin]

well I got my battery to hit 18 volts ! I think it was fully chrged so just could not take it anymore

If it hit 18V the battery was knackered

if the battery is flat I do need all the current I can get and can get it but a flat battery can go down quit low like 7 volts (we did it on my friends car with all the testing we did) so with a voltage difference of 6.5 volts the charge current can be very high and high enough to burn the dynamo out so current regulation is also implemented to prevent a literal meltdown, in cold weaher i can allow that to be a bit more current but must stop things overheating

The dynamo will only provide a certain amount of current, and shoudn't be able to burn itself out while just doing it's designed job.

I think the hysteresis in the old reg was due to the voltage being sampled off the battery so there was a delay in rise and fall of voltage, I am taking the measurements from the dynamo itself

You should take the measurement off the battery - the point of it is to protect the battery, so it would be foolish to monitor elsewhere. Hysteresis isn't any problem, and is a function of the electro-mechanical operation of the original regulator.

 

[Hero999]

Going from what he's told me before in another thread, the dynamo is poorly designed and other car owners have had problems with them burning out. One of the reasons for designing this circuit is to fix the problem of the dynamos burning out.

I agree 18V on a lead acid battery isn't going to do it any good but it shouldn't be fatal on a flooded lead acid battery.

 

[Thunderchild]

Well maybe the battery is knackered by my point is that the dynamo can reach high voltages, indeed it is the battery that ballasts the system, if you just disconected it you would have a big bang.

The dynamo can supply much more than it is rated for hence the regulation, as I said when my reg went out of control I got 30 amps from a 20 amp dynamo before blowing the reg, I don't know what voltage it got to but the battery was very flat by then.

I personally found no difference between taking reading off the battery or the dynamo except that when taken off the battery it was a little less steady, if the battery voltage rises the voltage on the dynamo will rise too

 

[Thunderchild]

Going from what he's told me before in another thread, the dynamo is poorly designed and other car owners have had problems with them burning out. One of the reasons for designing this circuit is to fix the problem of the dynamos burning out.

I agree 18V on a lead acid battery isn't going to do it any good but it shouldn't be fatal on a flooded lead acid battery.

nope it is the regulators that are poorly made as they are made in india, I've seen a new versus old and the new ones are not that good, it is accepted that they may last 6 months to a year. they seem like simple devices but every part of the pysical construction is part of the regulation process, you replace a spring with a silly strip of metal and you start going down hill

 

[Nigel Goodwin]

In my experiences with dynamos (60's/70's) regulators used to be extremely reliable - I never changed one - although I've cleaned contacts on them occasionally.

Back in the 70's Practical Electronics did a project on a semiconductor replacement for them - if I recall correctly it used a 2N3055 and a few more descrete devices, that was all.

 

[Thunderchild]

Nigel, this project is for cars that are much older, more like 40's/50's, my friend and his dad have between them about 10 cars made in this period, the replacement regulators they buy when the originals eventualy conk out are not that good as they are made in India and then last 6/12 months, oh they look just like the originals but they are not as soundly built.

I know various deasigns have poped up here and there over the years, there are also different models of regs, I think the published designs mostly replace the bosch regs that do not have esplicit current control (the two unit type of reg), there is also the lucas regs that are "three unit" models and these also implement current control and are used on larger cars (one car is a 6 ton bently with a 7 litre engine), i plan on meeting the operation of these units and then they can fit them to whichever car they like

 

[Nigel Goodwin]

My experiences were 40's and 50's, I don't think they were used after that?.

I used to have a 1954 350cc Velocette that had a dynamo

Previous to that we had a lot of old bikes and cars we used to run in the fields and on the moors.

 

[pasanlaksiri]

There are tons of microcontrollers. I think its totally depends on you and what you are going to do with it.

 

[Thunderchild]

My experiences were 40's and 50's, I don't think they were used after that?.

I used to have a 1954 350cc Velocette that had a dynamo

Previous to that we had a lot of old bikes and cars we used to run in the fields and on the moors.

I beleive that they were used up until the late 70's, even the VW beatle camper vans use them, I checked my neihgbours one out.

 

[Nigel Goodwin]

I beleive that they were used up until the late 70's, even the VW beatle camper vans use them, I checked my neihgbours one out.

That would be the exception, presumably because they still used 6V system years after everyone else switched to 12V.

 

[Thunderchild]

That would be the exception, presumably because they still used 6V system years after everyone else switched to 12V.

didn't know that, but I thought I heard of someone making a semiconductor reg for a ford car of the 70's but might be wrong. I think mechanical regs may have held out for a long time until powerful semiconductors became viable and affordable

 

[Nigel Goodwin]

didn't know that, but I thought I heard of someone making a semiconductor reg for a ford car of the 70's but might be wrong. I think mechanical regs may have held out for a long time until powerful semiconductors became viable and affordable

It wasn't so much a question of that, but just that alternators rendered dynamos obselete.

 

[Thunderchild]

ah yes but the regulator in an alternator is not far off what the semiconductor regulator for a dynamo is, I would guess it was thought convenient to switch both generator type and regulator type. If I stuck a full wave rectifier on my regulator cicuit I'm sure it would run an alternator as well, I'm carrying 20 amps in my reg, with modern alternators putting out 60+ amps I'm sure any time before the 70's it would have been a feat to find diodes capable of that capacity without getting rather hot, or being huge exspensive but I might be wrong

 

[Nigel Goodwin]

ah yes but the regulator in an alternator is not far off what the semiconductor regulator for a dynamo is, I would guess it was thought convenient to switch both generator type and regulator type. If I stuck a full wave rectifier on my regulator cicuit I'm sure it would run an alternator as well, I'm carrying 20 amps in my reg, with modern alternators putting out 60+ amps I'm sure any time before the 70's it would have been a feat to find diodes capable of that capacity without getting rather hot, or being huge exspensive but I might be wrong

Why would you want to do that?, and it wouldn't be much use anyway, as alternators require (and include) a three phase rectifier.

Certainly the control is done in an identical way, you lower the field current in order to reduce the output of the generator.

Your thinking on rectifiers is also incorrect, large rectifiers go back MUCH longer than that, don't limit your imagination to silicon!.

 

[Hero999]

Your thinking on rectifiers is also incorrect, large rectifiers go back MUCH longer than that, don't limit your imagination to silicon!.

But they contained mercury encases in an glass envelope which produced lots of dangerous UV radiation and had to be operated the right way up; not very suitable for automotive used.

Mercury arc valve - Wikipedia, the free encyclopedia

 

[Thunderchild]

I know there were "metal rectifiers" indeed it is amazing that all those years ago a mechanical device could function practically as well as a modern electronic device