Dynamo / Electronic regulator woes

[Petebarn]

I've had same probs with my nh couldn't get the new wassel to work so I put mechanical one back on bingo its charging I can only put it down to bad connections, but no way could I get the new one to work spent 3 days trying

[Keith.owen]

Hi,
Who was the manufacturer of the regulator?

Thanks and BR,
Keith

[bill.bottrill]

It's important to know the basics of what the regulator is for,In the Ariel mech. one there are two coils.They have two different job's to do,If you just connected the dynamo to charge the battery everythings fine,but when the bike stopped (no charge )and so all the charge will run the other way from the battery into the dynamo and eventually a flat battery so one of these coils pulls in or drops out around 6 volts breaking a set of contacts on the back of the coil. this isolates the dynamo from the battery circuit...Now the other coil also has a set of contacts on the back of the coil but whereas the first coil contacts are open at rest these ones are closed at rest they are connected to the field coil (so they are doing what you did by joining the F and D wires together) again no problem voltage increases and as you have found it doesn't stop at 6 volts it will keep going the faster it turns, this is not good for a 6 volt battery and not good for the dynamo designed for 6 volts (so as voltage increases above 6 volts the contacts normally closed start to vibrate which starts to lower the voltage to the field coil so the dynamo stops increasing the volts)
Unfortunately (and I've done it myself) people fiddle with the setting screws randomly and bu^^er it up It's a little more complicated than this ,hence the extra wiring but this is also what the electronic unit does there's no extra magic really

[Keith.owen]

Hi,
Having read the manual for the MCR2 I feel confident to set one up. I'd put money on it that the one I took out of the box, if re-installed will work if set up properly, provided the field coil series resistor is ok. The manual doesn't say what the resistance value is. Does anyone know?

The problem I'm having with the electronic regulator is that it doesn't seem to be switching on and therefore no current is passing through the field coil.

I am interested to see that Peter also had problems with a Wassel.

It is interesting to note that the Wassel requires that the field coil polarity be reversed and connected to the dynamo output terminal 'D'. The field coil is then pulled to ground, via the 'F' terminal, to get current to flow through it from the dynamo. Because the regulator is electronic there will be some sort of device (power transistor) that will first need switching on, so, maybe my dynamo just isn't outputting enough voltage without a field coil in circuit to ever activate it / switch it on? Sadly, there doesn't seem to be any technical support / help desk for these devices.

I'm pretty certain that my dynamo is ok though. It easily powers a 21 Watt 12 Volt bulb at low revs!!

The electronic regulator should, in theory, give as good if not better results as a mechanical device, and is essential if you want to run 12 volt electrics (which I want to do with my NH project). I also parted with £30 odd so I'm reluctant to just throw the Wassel in the bin without a fight!

Keith

[chris.shearwood]

Because the regulator is electronic there will be some sort of device (power transistor) that will first need switching on, so, maybe my dynamo just isn't outputting enough voltage without a field coil in circuit to ever activate it / switch it on?

Hi Keith,
I remember having an electronic regulator many years ago which required "priming of the pump" before it would work. Momentarily, when the motor was idling, jumping the D output of the dynamo to the F wire did the job. Perhaps yours is the same?

[nevhunter]

Plenty of alternators in light aircraft require "exciting" momentarily to get them to produce any output. This usually comes from the battery, via a "start OFF run" switch. IF it's not reasonably charged you are out of luck. Your original Lucas generator relies on residual magnetism in the mild steel case. It may possibly be not sufficient to start it with the modern "solid state" regulator. Even the complete original set-up if left for a while, may be reluctant to "pull in" the cutout mechanism and require "flashing" of a terminal. Once that's done once it's usually OK in regular use. Nev

[Keith.owen]

Hi,
I'm going to do two things:
1) Refit the mechanical regulator
2) Do some bench testing of the electronic regulator - I need to get the boys downstairs to lend me one of their nice lab power supplies.

I will report back.

Keith

[Eero.Korhonen]

Hi,
I'm going to do two things:
1) Refit the mechanical regulator
2) Do some bench testing of the electronic regulator - I need to get the boys downstairs to lend me one of their nice lab power supplies.

I will report back.

Keith

That is always a good idea to check with power supply.
Br, Eero

[bill.bottrill]

It would be quite interesting to actually see the wiring details for the wassel reg. I understand what you are saying about not getting the current to flow in the field coil circuit (ie the reg isn't swiching on initially) I know it's difficult to explain on this forum and discribe a fault without causing further unintentional problems,but you state the wassel requires the field coil polarity to be reversed!!well if you do this it means the output from D will be reversed . Sorry I forgot about the resistor in the field coil circuit (I said the MCR2 reg was more sophisticated ) this is a resistor bridging the regulator contacts, when contacts are closed the resistor has no function, when contacts open it just puts more resistance in the circuit,so it cuts the current through the field coil slightly,this would perhaps save quite a bit of arcing on the points.
I'm actually travelling at the moment so unable to check the resistor in question.

[alan.moore]

It is interesting that the Wassell POSITIVE earth version does not appear require any change to the dynamo wiring I have read on various bike forums tales of folks who have had problems with the negative earth version. many cahnge to PoS earth so they do not have to play about with ther dynamo wiring
I've looked at the negative earth diagram and to my mind they have the two diagrams titles mixed up. The one on the right (which they say is the 'revised configeration' is the normal way a dynamo is wired up and is the same as their diagram in the positive earth instructions.

The left side neg earth diagram (shown as old configuration) I think is in fact the revised configuration...but I could be wrong so don't quote me on this. I am sure there must be someone on the forum with more electrical knowledge of charging systems than me

neg eath wassell.pdf

neg earth

(111.97 KiB) Downloaded 231 times

pos earth wassell.pdf

pos earth

(102.36 KiB) Downloaded 215 times

The DVR2 regulator gets good reports.

Cheers
Alan