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Misc: Charging Systems JG Regulator

Howard

Well Known and Active Website User
VOC Member
Does anyone still use a JG unit?
I gave up on them in the 70s when I was trying to run coil ignition and 55 watt headlight - I should have known you don't get owt for nowt - a boiled battery while riding with lights on in France convinced me I needed an alternator. My French at that time was based on the PG tips advert "Av ay voo oon bat tery?" so finding a replacement was a bit traumatic. :(
My Comet, that only does daytime miles with a BT-H mag, has just burnt out it's V Reg solid state regulator, and I'm tempted to fit the old JG unit.
Any Comments?
H
 

Bill Thomas

Well Known and Active Website User
VOC Member
Mine burnt out half way to the IOM, So I gave up on them,
My Comet is still like yours, Turned into the Forest a few years ago ! , Thick Fog, So came out quick !.
I have a Walkernator , Bit like the Mini car alternator that I have had on my Special for many years,
Ready to fit if I ever do a big job on it.
And another for the new Comet if I ever get it done.
I think they look nice and well made.
Don't know if T.T. has any left ???.
 

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Howard

Well Known and Active Website User
VOC Member
I'm keeping the Comet as standard looking as possible but the Egli has used a 360 Watt Citroen alternator for about 40 years. It's so old it was made in Yugoslavia - find that on a modern map, if you can. :)
 

Ken Tidswell

Well Known and Active Website User
VOC Member
Does anyone still use a JG unit?
I gave up on them in the 70s when I was trying to run coil ignition and 55 watt headlight - I should have known you don't get owt for nowt - a boiled battery while riding with lights on in France convinced me I needed an alternator. My French at that time was based on the PG tips advert "Av ay voo oon bat tery?" so finding a replacement was a bit traumatic. :(
My Comet, that only does daytime miles with a BT-H mag, has just burnt out it's V Reg solid state regulator, and I'm tempted to fit the old JG unit.
Any Comments?
H
the JG unit over drives the field coil which is only designed for 6 volts. You can now get a 12 volt field coil
and retrifit it to your dynamo. It should be then OK,If you go to a LED head lamp bulb you should then be better still because of the reduced power requirements. At some stage with aJG if you had a flat battery and ran coil ignition AND a50 watt headlamp bulb the armature over heated and threw the solder off the armature and it then peacefully died , but anly after several months of operation. The best combination was a Chinamo and aJG unit they would charge all day at 4amps. In this case the armature wires were crimped to the comutator
 

timetraveller

Well Known and Active Website User
VOC Member
Regarding Bill's question above, I do not have any left apart from ones built for my own use but I could easily make some more as I have several of the specially machined parts left over. For all the most recent ones I have used a Nippon Denso 40 amp alternator with the regulator built in, It has a slightly smaller diameter than the original Iskra 30 amp ones which were made in Slovenia. I had to buy those in tens to keep the price down and so I now buy the ND ones as one offs. Several people have had these for years and are very happy with them.
 

Howard

Well Known and Active Website User
VOC Member
the JG unit over drives the field coil which is only designed for 6 volts. You can now get a 12 volt field coil
and retrifit it to your dynamo. It should be then OK,If you go to a LED head lamp bulb you should then be better still because of the reduced power requirements. At some stage with aJG if you had a flat battery and ran coil ignition AND a50 watt headlamp bulb the armature over heated and threw the solder off the armature and it then peacefully died , but anly after several months of operation. The best combination was a Chinamo and aJG unit they would charge all day at 4amps. In this case the armature wires were crimped to the comutator
Hi Ken,
I suspect you mean a 12 volt Armature. The one I just burnt out was a 12 volt armature, the problem is, as I understand it, (and I'm not an electician) you need twice the length of wire in the same space to get 12 instead of 6 volts and that makes it very susceptible to insulation breakdown etc. Maybe someone can confirm this.
H
 

Peter Holmes

Well Known and Active Website User
VOC Member
I ran a 6 volt JG for many years, I cannot remember it ever given any problems when used with a 6 volt Miller dynamo, even ran a low wattage H4 bulb, 35 amp I think, then Norman fitted my Nippon Denso alternator for me, well now you are talking reliable, high power electrics, I can even ride a night, with cataracts!
 

highbury731

Well Known and Active Website User
VOC Member
Does anyone still use a JG unit?
I gave up on them in the 70s when I was trying to run coil ignition and 55 watt headlight - I should have known you don't get owt for nowt - a boiled battery while riding with lights on in France convinced me I needed an alternator. My French at that time was based on the PG tips advert "Av ay voo oon bat tery?" so finding a replacement was a bit traumatic. :(
My Comet, that only does daytime miles with a BT-H mag, has just burnt out it's V Reg solid state regulator, and I'm tempted to fit the old JG unit.
Any Comments?
H
The DynamoRegulators unit is better, and can be set up to deliver 6V or 12V
 

john h

New Website User
VOC Member
thanks howard, to get my miller/jg system to work i have to connect a stoplight bulb between positive terminal and D. at tickover bulb is bright and goes out as revs rise , the ammeter then registers a charge lights work and charge is balanced . next time it is started -no charge !
 

delboy

Well Known and Active Website User
VOC Member
thanks howard, to get my miller/jg system to work i have to connect a stoplight bulb between positive terminal and D. at tickover bulb is bright and goes out as revs rise , the ammeter then registers a charge lights work and charge is balanced . next time it is started -no charge !
You may find that the air gap twixt armature and field coil is too big.
I once had exactly the same fault on a bike and found someone had skimmed the armature to "tidy it up".
Duuuh!
A new armature and setting the gap restored normal service, so no fault of the much maligned JG.
Regards,
Delboy.
 

vibrac

Well Known and Active Website User
VOC Member
Never the less, apart from Acetylene gas there is nothing more dated than a JG regulator :rolleyes: I have two or three in cubbyholes somewhere most with NBG scrawled on them by 'experts'
 

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