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AC powered fin strobe

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Richard Lamprey

Joined: 15 Jul 2011
Posts: 95
Location: Kenya

Posted: Fri Dec 09, 2011 10:12 pm Post subject: AC powered fin strobe

My fin mounted 12V DC Filser strobe went u/s, and I have spent some time looking for a similar strobe that will fit in the hole in the fin (5 cm exact diameter).  I settled on the Illusion strobe from the US (mostly used for ultralights), the only one that will fit, and this is powered directly from the Rotax 912 magneto generator, which supplies 12V AC.  I am told it has an exceptionally bright flas.  The strobe power box is wired in series between the 912 generator wires (yellow) and the Ducati voltage rectifier. Also, strangely, there is no circuit breaker or fuse in this system.  Has anyone installed an Illusion AC system before, or similar?  Are there problems, does it blow the rectifier?  The supplier assures me this is a common installation with 912 engines, and there are no problems.

rholder(at)avnet.co.uk
Guest

Posted: Sat Dec 10, 2011 1:39 am Post subject: AC powered fin strobe

On 10/12/2011 06:12, Richard Lamprey wrote:



 	  Quote: 	
		   My fin mounted 12V DC Filser strobe went u/s, and I

 have spent some time looking for a similar strobe that

 will fit in the hole in the fin (5 cm exact diameter).

 I settled on the Illusion strobe from the US (mostly

 used for ultralights), the only one that will fit, and

 this is powered directly from the Rotax 912 magneto

 generator, which supplies 12V AC.  I am told it has an

 exceptionally bright flas.  The strobe power box is

 wired in series between the 912 generator wires

 (yellow) and the Ducati voltage rectifier. Also,

 strangely, there is no circuit breaker or fuse in this

 system.  Has anyone installed an Illusion AC system

 before, or similar?  Are there problems, does it blow

 the rectifier?  The supplier assures me this is a

 common installation with 912 engines, and there are no

 problems.


	


Be advised that the AC voltage out of the stator can be as

much as 30 v at full power.



That might explain why it is so bright.



Unless you really meant "in series" rather than the usual

"in parallel" !



If it works in series then it might be OK with a slightly

higher engine rpm before the battery gets charge.



RFWH

frans(at)privatepilots.nl
Guest

Posted: Sat Dec 10, 2011 6:25 am Post subject: AC powered fin strobe

On 12/10/2011 07:12 AM, Richard Lamprey wrote:



 	  Quote: 	
		   The

 strobe power box is wired in series between the 912 generator wires

 (yellow) and the Ducati voltage rectifier.


	


Wait a minute. Is it really in series? If both yellow wires go to the 

Ducati AND both go to the strobe, it is parallel. If one yellow wire 

goes to the strobe, and one yellow wire to the ducati, and a new wire is 

used to connect the remaining ducati and strobe connectors together 

(like how X-mas tree lights are wired), it is indeed series.

It is quite important to know whether it is parallel or series, hence my 

question.



 	  Quote: 	
		   Also, strangely, there is

 no circuit breaker or fuse in this system.


	


This would make sense if it is series indeed, otherwise you should use a 

fuse.



Anyway, I would advise for quite a number of reasons against a series 

diagram, but a parallel diagram would be ok. I would be surprised if it 

is series indeed, but you never know.



Assuming it is parallel, as it should be, I think it is a great 

solution. Strobes work on high voltages, so any strobe power supply 

needs to convert the low voltage DC into high voltage AC and then 

rectify it again. By feeding it directly from the alternator (where it 

is still AC) quite some losses can be avoided, and it also does not load 

the Ducati (which has a tendency to burn out easily). An AC-fed strobe 

can not be powered from the battery, but if the alternator fails the 

strobe is the first thing you should power down anyway, so this is no 

real disadvantage.

You should put a fuse between the alternator and strobe power unit. 

(Don't use a CB here, as you should never try to reset a tripped strobe 

CB during flight: it is not essential equipment and malfunctioning 

strobe power supplies are quite a hazard, so don't play with these 

things and just use a "one-time" fuse here to avoid any temptation!). I 

would put a switch in between too, as it is considered somewhat impolite 

to wait at the holding point with bright flashing strobes while there is 

someone on final, especially when it isn't very bright weather. I would 

also like to power down the strobe if I would smell any fuel during flight.



Frans

Richard Lamprey

Joined: 15 Jul 2011
Posts: 95
Location: Kenya

Posted: Sun Dec 11, 2011 4:06 am Post subject: Re: AC powered fin strobe

Yes, really meant in series... its is mak by Aircraft Spruce, heres the description, also the attachment shows the circuit:



Has no effect on the charging or electrical system.

*Works on a simple lighting coil system only...without a regulator or

*Will work along with a complex battery charging system...with a regulator

Designed for most Light plane engines..... Rotax, HKS, Hirth, Zenoah, MZ......

THE BRIGHTEST AC POWERED STROBE LIGHT AVAILABLE

25 JOULES (watt-second) and yet...

It is the most efficient strobe light available because...

It uses only the power that is normally wasted by a voltage regulator...

Unlike automobile regulators, U.L. regulators short to ground OR

dump all the current that is not used with the battery, wasting 4 to 15 amps and

that is why this strobe is so BRIGHT.

Will NOT drain battery and, in fact, NO BATTERY IS NEEDED !!

Can be connected directly to the lighting coil, NO voltage regulator is required

Uses the yellow wires out of the engine OR any 2 to 14 amp AC power source.

Illusion SimpleWiring-wSwitch.doc

Description:

Download

Filename:

Illusion SimpleWiring-wSwitch.doc

Filesize:

24.5 KB

Downloaded:

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frans(at)privatepilots.nl
Guest

Posted: Sun Dec 11, 2011 1:34 pm Post subject: AC powered fin strobe

On 12/11/2011 01:06 PM, Richard Lamprey wrote:



 	  Quote: 	
		   Yes, really meant in series...


	


It doesn't say so in the description. Why do you think it is intended to 

be connected in series?



 	  Quote: 	
		   also the attachment shows the circuit:


	


I didn't see any attachment.



 	  Quote: 	
		   Has no effect on the charging or electrical system.


	


Free electricity. Sounds to be too good to be true.



 	  Quote: 	
		   *Works on a simple lighting coil system only...without a regulator or


	


Maybe the Rotax two-cycle engines are different, maybe they are talking 

about that family of engines?



 	  Quote: 	
		   It uses only the power that is normally wasted by a voltage regulator...


	


The voltage regulator of the 912/914 doesn't "waste" enough power to 

power a strobe.



 	  Quote: 	
		   Unlike automobile regulators, U.L. regulators short to ground OR


	


I have the schematic diagram of the Ducati regulator somewhere, but as I 

recall it doesn't short to ground. If that were true, the regulators 

would become hotter when less current is used in the electrical system. 

That doesn't seem to reflect the reality.



 	  Quote: 	
		   Uses the yellow wires out of the engine OR any 2 to 14 amp AC power source.


	


If it uses both yellow wires it is a parallel system.



Anyway, it is interesting but I could nowhere find any more information 

than the one given on ACS, and that is a bit of gibberish to me.



So far I get the impression that the selling point of this thing is that 

you don't need a battery or regulator, which may be of interest to 

owners of ultra light aircraft, gyrocopters and other minimal setups.



Frans

paul.the.aviator(at)gmail
Guest

Posted: Sun Dec 11, 2011 3:14 pm Post subject: AC powered fin strobe

I am guessing that this strobe is targeted towards the 2 cycle family of Rotax engines.  It's appeal would be in its simplicity to wire up.  Neat idea.



do not archive.



On Sun, Dec 11, 2011 at 3:29 PM, Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)> wrote:

 [quote]--> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)> 

 

 On 12/11/2011 01:06 PM, Richard Lamprey wrote:

 

  	  Quote: 	
		   Yes, really meant in series...

 	
 



 It doesn't say so in the description. Why do you think it is intended to be connected in series?

 

  	  Quote: 	
		   also the attachment shows the circuit:

 	
 



 I didn't see any attachment.

 

  	  Quote: 	
		   Has no effect on the charging or electrical system.

 	
 



 Free electricity. Sounds to be too good to be true.

 

  	  Quote: 	
		   *Works on a simple lighting coil system only...without a regulator or

 	
 



 Maybe the Rotax two-cycle engines are different, maybe they are talking about that family of engines?

 

  	  Quote: 	
		   It uses only the power that is normally wasted by a voltage regulator...

 	
 



 The voltage regulator of the 912/914 doesn't "waste" enough power to power a strobe.

 

  	  Quote: 	
		   Unlike automobile regulators, U.L. regulators short to ground OR

 	
 



 I have the schematic diagram of the Ducati regulator somewhere, but as I recall it doesn't short to ground. If that were true, the regulators would become hotter when less current is used in the electrical system. That doesn't seem to reflect the reality. 

 

  	  Quote: 	
		   Uses the yellow wires out of the engine OR any 2 to 14 amp AC power source.

 	
 



 If it uses both yellow wires it is a parallel system.

 

 Anyway, it is interesting but I could nowhere find any more information than the one given on ACS, and that is a bit of gibberish to me.

 

 So far I get the impression that the selling point of this thing is that you don't need a battery or regulator, which may be of interest to owners of ultra light aircraft, gyrocopters and other minimal setups.

  

 Frans

[b]

jan_de_jong(at)casema.nl
Guest

Posted: Mon Dec 12, 2011 4:19 am Post subject: AC powered fin strobe

Voltage regulator is a "rectifier-regulator".

It is a "full wave rectifier" with 2 of the 4 diodes replaced by SCRs 

(thyristors).

All output current is supplied through the 2 alternating sets of 1 diode 

and 1 thyristor in series.

The voltage drop across these when they conduct (ideally zero) 

determines the loss.

The peak current through these is a multiple of output current because 

they conduct only a small fraction of the time. The peak current is 

limited by the internal resistance of the alternator coils and the 

internal resistance of the output storage capacitor.

See forward voltage at 50 A and 100 A for the SCR:

http://www.datasheetcatalog.org/datasheet/on_semiconductor/2N6504-D.PDF

See forward voltage at 50 A and 100 A for the diode:

http://www.datasheetcatalog.org/datasheet/on_semiconductor/MR2500-D.PDF

Ballpark voltage drop is 3 to 4 volts - 21 to 28% of output volts. Heat 

dissipation as a percentage of output power (watts) is the same number.

 From the datasheets it is clear that the voltage drop and therefore 

loss percentage increases quite progressively with high and increasing 

current.



If you can power a 40 W strobe directly from AC you may save 10 W or so 

in heat generation in the voltage regulator.



Cheers,

Jan de Jong

Richard Lamprey

Joined: 15 Jul 2011
Posts: 95
Location: Kenya

Posted: Mon Dec 12, 2011 9:58 pm Post subject: Re: AC powered fin strobe

Many thanks for all the replies, especially Frans and Jan for their technical responses.  I attach again the simplified wiring diagram, showing the in series connection, this diagram enclosed with the strobe, and also re-confirmed with the original manufacturer Air-Tech Inc.  



I am an ignoramus on electrical matters, so I'll close my eyes when making the final connection and hope there isnt a big bang from the rectifier (obviously this thing will only work when the engine is running).  One reason I am a little cautious is that Ducati rectifiers are not very consistent and reliable, and having seen this one serve me well for about 7 years I would hate to wreck it.



All best

Richard

Europa Classic 168, Kenya

ILLUSION AIRCRAFT STROBE from Aircraft Spruce.pdf

Description:

Download

Filename:

ILLUSION AIRCRAFT STROBE from Aircraft Spruce.pdf

Filesize:

87.54 KB

Downloaded:

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Illusion SimpleWiring-wSwitch.doc

Description:

Download

Filename:

Illusion SimpleWiring-wSwitch.doc

Filesize:

24.5 KB

Downloaded:

268 Time(s)

jan_de_jong(at)casema.nl
Guest

Posted: Tue Dec 13, 2011 8:54 am Post subject: AC powered fin strobe

Hi Richard,



Not the way we are used to connecting loads to power sources indeed.

I don't like the fact that your DC power supply and your strobe box are 

now mutually dependent.

Mind that the optional switch drawn has to carry 15 A average and 100 A 

peak (<1 ms).

But it will probably work well enough.

A power supply is generally used as a voltage source. The load takes 

some current away that does not affect the voltage (ideally).

In this case usage is reversed. The load takes some voltage away that 

does not affect the current (too much, we hope).

The strobe input may be an up transformer with a few fat primary 

windings and many thin secondary windings.

It probably takes away a certain percentage of the AC voltage available.

You will need somewhat more RPM than before for DC to reach normal 

performance.

That should be all, actually.



Regards,

Jan de Jong

frans(at)privatepilots.nl
Guest

Posted: Tue Dec 13, 2011 9:10 am Post subject: AC powered fin strobe

On 12/13/2011 06:58 AM, Richard Lamprey wrote:

 	  Quote: 	
		   I attach again the simplified wiring diagram,

 showing the in series connection, this diagram enclosed with the

 strobe, and also re-confirmed with the original manufacturer Air-Tech

 Inc.


	


It is indeed in series!

Well, my ideas on this:

The total aircraft electrical power consumption will have to go through 

the strobe box and its associated wiring. All of it. This means that if 

you put the strobe box in the fin, all electrical current for whatever 

avionics you have, will have to travel through the wires, forth and back 

to the tail.

This has the following implications:

1) you need to run very heavy wires, to keep current losses acceptable. 

The wires do not just carry the current for the strobe, but the current 

for the total electrical load of the entire aircraft.

2) You can not install a light fuse, you have to use a fuse higher than 

the total power demand of the aircraft. Think about something like 30 

Amps. If you have a short circuit somewhere but the current stays below 

30 Amps, the fuse won't blow but all this energy is converted into heat. 

This is a fire hazard.

3) The long wires will act like an antenna. Alternators AND strobes are 

both notorious for their electrical noise. It may have an influence on 

your radio.



Therefor, I would highly recommend to put this strobe box as close to 

the alternator as possible. This again has the implication that you will 

have to run long wires to the strobe bulb, but at least these wires do 

not carry large currents.



Also be aware that your electrical system becomes completely dependent 

on the strobe box. If it blows open circuit, it takes the whole 

electrical system with it. You definitely need to incorporate a 

short-circuit switch, to bridge the strobe box in case it fails open 

circuit.



There is no such thing as "free electricity". Anything in series with 

the voltage regulator will have its impact on the performance of the 

electrical system. I can't judge from here how bad it is. But the Rotax 

power system isn't powerfull to start with.



Best regards,

Frans

Richard Lamprey

Joined: 15 Jul 2011
Posts: 95
Location: Kenya

Posted: Wed Dec 14, 2011 7:14 am Post subject: Re: AC powered fin strobe

Thanks Frans and Jan,



An additional wiring diagram shows the switch that by-passes the strobe box from the AC supply as 20 Amp, so there's a hefty current.  I'll be putting the box as close to the rectifier as possible, and use the existing 22 AWG strobe wiring from the previous installation for connection to the strobe in the tail.  There will be no point to running the AC strobe continuously, but mainly flying in the circuit, approach, on the apron, etc.  Lets see what happens.

Best

Richard

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