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Rotax regulator

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rholder(at)avnet.co.uk
Guest

Posted: Sat Jan 28, 2006 10:53 am Post subject: Rotax regulator

Gilles Thesee wrote:

 	  Quote: 	
		  > Do you think it is right if the alternator needs to

> be switched off manually for any reason that it

> should be done through the C terminal (switching an

> amp or two) rather than the B+/R terminal which is

> perhaps pushing out 15 - 20 amps.

 	  Quote: 	
		   The Rotax regulator will normally shut down when the C

 terminal is grounded (zero volt). Can't predict what it

 does when just disconnected. What if it doesn't tame

 the regulator output ?

Is there some way of checking this ? Perhaps on your

student's test rig ?

 	  Quote: 	
		   Have you considered including a relay in the B/R to bus

 circuit ? Bob Nuckolls' Aeroelectric figure Z 16 could

 be of interest. My design is a variation on Bob's

 theme, with small changes due to the different

 regulator.

I just didn't want to use a physical switch/cb/relay to go

from an overvolt situation of maybe 30 A to nothing. It

would not be good for the switch/cb/relay, IF

disconnecting the C terminal turns off the regulator then

there will be no actual disconnection spark anywhere, it

will be in the electronics.

 	  Quote: 	
		   The C wire is a sense wire, so AWG 22 and 5 amps is

 about right.

5 amps actual seems like a lot for a sense wire. That

means that the regulator B+/R terminals produce up to 24A

of which 5A goes back into the regulator ?

I have seen your fine pictures of the cleaned out

regulator. It appears that B+ and R are connected together

inside anyway !

Could you send me the schematic of the circuit inside there ?

I have a friend who dabbles in obscure components. He

looked up TP154E. It is a Thrystor 800 volt 25 A 40mA and

an alternative would be 2N6509 which in my catalogue is

about 1 GBP - say 2 euros !

 	  Quote: 	
		   Hope this helps,

It does and I hope I have helped in return.

Gilles.Thesee(at)ac-greno
Guest

Posted: Sat Jan 28, 2006 1:43 pm Post subject: Rotax regulator

Hi Richard,



 	  Quote: 	
		  > What if it doesn't tame

>the regulator output ?

>    

>



Is there some way of checking this ? Perhaps on your

student's test rig ?



  



Hmm, remember that was two years ago. I'm afraid the alternator might 
	


now lie on a forgotten shelf...



 	  Quote: 	
		  >Have you considered including a relay in the B/R to bus

>circuit ? Bob Nuckolls' Aeroelectric figure Z 16 could

>be of interest. My design is a variation on Bob's

>theme, with small changes due to the different

>regulator.

>    

>



I just didn't want to use a physical switch/cb/relay to go

from an overvolt situation of maybe 30 A to nothing.



 It

would not be good for the switch/cb/relay, IF

disconnecting the C terminal turns off the regulator then

there will be no actual disconnection spark anywhere, 



Grounding the C wire will shut down the regulator. That is, IF it is 
	


working properly. But then where does that OV condition come from ?



 	  Quote: 	
		  >The C wire is a sense wire, so AWG 22 and 5 amps is

>about right.

>    

>



5 amps actual seems like a lot for a sense wire. That

means that the regulator B+/R terminals produce up to 24A

of which 5A goes back into the regulator ?

  



5 amps is the usual CB rating for AWG 22 wire. And for mechanical 
	


reasons, AWG 22 is about the smallest wire used for wiring light aircraft.

Remember, if your crowbar fires, the current will flow from the bus bar 

via the OV CB, to the ground, tripping the CB in the process.



 	  Quote: 	
		  I have seen your fine pictures of the cleaned out

regulator. It appears that B+ and R are connected together

inside anyway !

  



Yes
	




 	  Quote: 	
		  Could you send me the schematic of the circuit inside there ?

  



Will do. Just give me some time to sort the 40+ MB of data Jerome just 
	


sent me. I would like to publish something really up to date.



 	  Quote: 	
		  I have a friend who dabbles in obscure components. He

looked up TP154E. It is a Thrystor 800 volt 25 A 40mA and

an alternative would be 2N6509 which in my catalogue is

about 1 GBP - say 2 euros !

  



Great !
	


Thank you,

Gilles

http://contrails.free.fr

Gilles.Thesee(at)ac-greno
Guest

Posted: Sun Jan 29, 2006 2:34 pm Post subject: Rotax regulator

 	  Quote: 	
		  

Could you send me the schematic of the circuit inside there ?

  




	


Richard an all,



I just posted a schematic of the Rotax regulator.

Please note that I redrew it from sketches two years old, and I'll check 

with a dismantled unit, well er...later 



FWIW

Regards,

Gilles Thesee

Grenoble, France

http://contrails.free.fr

william(at)wrmills.plus.c
Guest

Posted: Mon Jan 30, 2006 11:35 pm Post subject: Rotax regulator

Hi Gilles,

Do you consider the Rotax regulator could develop an intermittent fault so 

that it is not always charging at full capacity?  I have noticed in flight 

that sometimes the voltmeter drops to about 13 V and other times it stays at 

14 V (13.8, I presume).  Last time I brought the aircraft home the battery 

was not full charged and needed some time on the charger to top it up.  The 

battery is an Odyssey PC680 and is only one year old.

Many thanks,

William



---

Gilles.Thesee(at)ac-greno
Guest

Posted: Tue Jan 31, 2006 10:02 am Post subject: Rotax regulator

William Mills a crit :



 	  Quote: 	
		  Do you consider the Rotax regulator could develop an intermittent fault so 

that it is not always charging at full capacity?  I have noticed in flight 

that sometimes the voltmeter drops to about 13 V and other times it stays at 

14 V (13.8, I presume).  Last time I brought the aircraft home the battery 

was not full charged and needed some time on the charger to top it up.  The 

battery is an Odyssey PC680 and is only one year old.

Many thanks,

  



Richard and all,
	




It would be interesting to study what electrical devices are on, and 

what the engine RPM are, versus voltmeter readings. It is normal to see 

the bus voltage drop when the current draw is high. It also depends on 

the battery state of charge.



Now, if there is a problem, yes the regulator could be the culprit, but 

there are so many other causes to investigate.

Frequent problems are faulty wiring, especially the connection between 

the regulator case and the ship's ground. Remember your 14-18 charging 

amps flow through this connection.

Every connection in the circuit should be checked for tightness, absence 

of corrosion, correct wire gauge, etc.

Also, you need a thorough load analysis in order to be sure your 

permanent draw does not exceed 10-12 amps. And remember the alternator 

delivers power when RPM is sufficient, that is around 5000 RPM.



Do you have a schematic of your aircraft circuit ?



Regards,

Gilles Thesee

Grenoble, France

http://contrails.free.fr

rholder(at)avnet.co.uk
Guest

Posted: Tue Jan 31, 2006 3:05 pm Post subject: Rotax regulator

I checked the C terminal. Disconnecting it does eventually

kill the charging but not very quickly, so disconnecting

the C connection via a crowbar won't work.



At about 5000 rpm the C terminal was taking 0.04 A.

Not-a-lot !



Gilles - I notice you say that earthing the C terminal

will kill the output. But your own wiring diagram shows

that the C terminal is connected directly to a diode which

would not allow any current to run to earth from inside

the regulator ! So I suspect your "earthing" of the C

terminal was really just disconnecting it.



I replaced my original (intermittent fault) rectifier

today and it worked. So the replacement (which flicked the

ammeter needle between 1 - 10 amps 5 times a second over

5000 rpm) was faulty and it will be on its way back to the

supplier tomorrow !



I actually looked at the circuit board of my original (now

re-installed) regulator and saw three possible sites for

dry-joints. So I applied my soldering iron. The regulator

still works so I didn't bu**er it up; I will wait for a

few flights before I proclaim that I have fixed the

intermittent failure to charge !



Richard with positive engineering news about the

electrics. So now to continue to determine why the oil

thermostat doesn't work the way I expected.



G-OWWW High Cross

Gilles.Thesee(at)ac-greno
Guest

Posted: Tue Jan 31, 2006 3:27 pm Post subject: Rotax regulator

Hi Richard and all,



 	  Quote: 	
		  



I checked the C terminal. Disconnecting it does eventually

kill the charging but not very quickly, so disconnecting

the C connection via a crowbar won't work.

  



In our circuit, the crow bar connects the C wire to ground, so it sees 
	


zero volt. At the same time, it trips the alternator disconnect CB, 

opening the line relay. So the alternator is totally disconnected from 

the ship's circuit.



 	  Quote: 	
		  At about 5000 rpm the C terminal was taking 0.04 A.

Not-a-lot !



Gilles - I notice you say that earthing the C terminal

will kill the output. But your own wiring diagram shows

that the C terminal is connected directly to a diode which

would not allow any current to run to earth from inside

the regulator ! 



Correct. The C terminal is a sense connection to provide a reference 
	


voltage to the command circuit. When you ground it, the reference 

voltage is zero volt.

No current is intended to flow out of it. C voltage is always greater 

than or equal to zero volt.



 	  Quote: 	
		  So I suspect your "earthing" of the C

terminal was really just disconnecting it.

  



What voltage does C teminal see when it is left dangling "in the air" ?
	




 	  Quote: 	
		  I replaced my original (intermittent fault) rectifier

today and it worked. So the replacement (which flicked the

ammeter needle between 1 - 10 amps 5 times a second over

5000 rpm) was faulty and it will be on its way back to the

supplier tomorrow !



I actually looked at the circuit board of my original (now

re-installed) regulator and saw three possible sites for

dry-joints. So I applied my soldering iron. The regulator

still works so I didn't bu**er it up; I will wait for a

few flights before I proclaim that I have fixed the

intermittent failure to charge !



Richard with positive engineering news about the

electrics.



Great news.
	




 	  Quote: 	
		   So now to continue to determine why the oil

thermostat doesn't work the way I expected.



  



Maybe I missed previous messages, but how should it work, and how does 
	


it behave ?

We shunned the thermostat thing, and went the duct and cowl flap route, 

with great satisfaction.



Regards,

Gilles Thesee

Grenoble, France

http://contrails.free.fr

william(at)wrmills.plus.c
Guest

Posted: Tue Jan 31, 2006 10:33 pm Post subject: Rotax regulator

Thanks John and Gilles,

I'm afraid I don't have a schematic, but I have several hundred hours with 

the same loading regime and I have noticed a change in the readings on the 

VDO voltmeter over the past 3 months or so.  It is also intermittent.  I 

will check all my connections, however.  Would a smear of grease help to 

maintain a good connection?

B w,

William



Do not archive



---

n3eu(at)comcast.net
Guest

Posted: Wed Feb 01, 2006 7:17 am Post subject: Rotax regulator

Richard Holder wrote:

 	  Quote: 	
		  

 I checked the C terminal. Disconnecting it does

 eventually kill the charging but not very quickly, so

 disconnecting the C connection via a crowbar won't work.


	


The delay is because a capcitor has to first discharge internally;

grounding won't do that..



 	  Quote: 	
		   So I suspect your "earthing" of the C

 terminal was really just disconnecting it.


	


Thus correct, because of that blcking diode. What grounding will do is

prevent spurious noise from triggering the sense circuit, which is a

hair-trigger "Darlington amplifier,"  though a rather low input

impedance for that sort of problem.



 	  Quote: 	
		   I actually looked at the circuit board of my original

 (now re-installed) regulator and saw three possible

 sites for dry-joints.


	


Anything's possible.  It looks hand-soldered, but by someone "on a

mission."  And apparently still did a poor job where it really mattered!



Reg,

Fred F.

hansjd(at)online.no
Guest

Posted: Thu Feb 02, 2006 2:08 pm Post subject: Rotax regulator

Hi William



It might be a good idea - if you havn't done so already - to check the 

grounding wire(s) and connections from the rectifier housing. Poor 

connections in this area will certainly ruin your day!



Best wishes, Hans - hansjd(at)online.no



---

william(at)wrmills.plus.c
Guest

Posted: Fri Feb 03, 2006 2:10 am Post subject: Rotax regulator

Many thanks, Hans,

I will certainly do that.

I was hoping one of the experts would comment on my suggestion to put a 

smear of grease on all the earthing terminals to improve contact and prevent 

corrosion.

Best wishes,

William



Do not archive



---

Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Fri Feb 03, 2006 2:48 am Post subject: Rotax regulator

Hi William,

A smear of grease might be Ok after you have connected the earth terminals

but not before.  You want the best possible electrical contact and this

requires a chemically clean joint- grease on the contact face is not good.



Brian Davies kit 454



--

ptag.dev(at)tiscali.co.uk
Guest

Posted: Fri Feb 03, 2006 7:34 am Post subject: Rotax regulator

Hi! William

My experiences indicate that the grease you need is electrical silicone

grease and is mostly available now in an aerosol can dispenser.

Of course you knew this anyway !!!!

Regards

Bob Harrison G-PTAG Europa MKI/Jabiru 3300



Robt.C.Harrison

--

william(at)wrmills.plus.c
Guest

Posted: Sat Feb 04, 2006 4:29 pm Post subject: Rotax regulator

Many thanks Brian and Richard; message taken.  What about switch or contact 

cleaner in the aerosol cans?

B w

W



Do not archive



---

Brian Davies

Joined: 10 Jan 2006
Posts: 124
Location: uk

Posted: Sun Feb 05, 2006 12:43 am Post subject: Rotax regulator

William,



It depends what you are trying to achieve.  If the contact/connection is

just dirty or greasy the contact cleaner will be fine.  It evaporates very

quickly leaving no residue.  If the contact/connection is corroded it will

not help. You need to mechanically remove all corrosion before making the

connection.



If you are worried about future contamination or corrosion after having made

a good connection, Richard's suggestion of using a small smear of Vaseline

or silicone grease will work. If you want to seal the connection permanently

from the elements you could cover it in RTV/ silicone bath sealant.



Hope this helps



Brian 



--

william(at)wrmills.plus.c
Guest

Posted: Sun Feb 05, 2006 10:52 pm Post subject: Rotax regulator

Many thanks, Brian,

I have had some cold weather starting probs plus the intermittent no 

charging (I think), so while it is at home I thought I would do as much as 

possible to improve whatever I can.

Best wishes,

William



---

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