tick tick... tick tick... need strobe light help *fixed*

[Learjet]

The previous owner of my gyro fitted 2 of these security alarm type strobes:


As they are not very effective, I thought I'd upgrade to a pair of these LED strobes:


Prior to installation I tested the new LED strobes using the existing wiring & switch etc (i.e simply swapped the old strobes with the new) and found that with the new LED strobes I hear a constant "tick tick...tick tick...tick tick" clicking sound interference through both the pilot & pax headsets (irrespective of VHF radio being on or off).

Surprising, as the previous el-cheapo strobes (which I presume have a capacitor) hardly created any interference at all and I thought the capacitor-free LED strobes would have even less of a potential interference issue?

I've tried using ferrite rings on the wiring to no avail.

Spoke to the supplier this evening who seemed surprised that I was experiencing this, as apparently LED strobes offer significantly less interference than regular filament strobes. He has undertaken to get their electronics chap to call me, and also to his credit has immediately promised to test and replace the units) - but as the units seem to be working perfectly in every other respect I'm thinking that the problem lies on my (gyro's) side?
I haven't started to remove and krap behind the instrument panel yet to see how/ where the existing strobe wiring runs from / power source etc.

Any tips or suggestions from the electrickery gurus out there would be appreciated! thanks

[Wallaby]

There's a video on You(fools)tube of a led strobe combo that's connected to a power source and it also made that tick tick noise. So maybe your antenna wires is to close to the strobe wires and they pick up the interference. Don't know really, it's just an observation.

What make of strobes are these that you've installed?

[ZULU1]

Dave, I am not surprised that you are experiencing this, a LED strobe circuit or should I more correctly say a LED has different requirements from a Xenon strobe. They most probably use a 555 chip and a SCR (Thyristor) to switch the time cycle. Now a LED or lots of them will give a back emf I would imagine. Never measured it ? Thats not unlike the industry standard relay coil snubbing circuit where a diode is placed across the coil of the relay to prevent circuit noise. So before you try anything with ferrites chokes etc. Contact Tobie in Cape Town from Electrocomp (hes on this forum) and ask him to give you a few 1N5822 diodes (3amp Schottky) or similar, place these as close as possible to the LED strobe and between the positive and negative supply. I bet it works and let us all know please. I am keen to learn.

Cheers Paul

[Learjet]

Thanks for the good suggestion Paul. Before I chat to Tobie I'll contact to the manufacturer on Monday, confirm what chip etc they've used and just get their OK to try the diode fix before I inadvertently void their warranty.

Wallaby - thanks as well - I tried to find the youtube reference but to my surprise there are 3540 videos related to "led strobe light" so I might try the diode route before settling down with some popcorn and coke

Thanks
Dave

[ZULU1]

Dave, this is a useful contact also, I have used these products when I used to work with SCR controllers in ovens and spot welder controls. Advise them of the exact type of product you have with the type of switching (it must be a SCR) and also probably the flash rate and they should give you a suitable answer. Try the diode first, it will do no harm to the toys. Let us all know the outcome please ? I like to learn...

http://www.supprescraft.co.za

For others info they can help with engine derived interference also...

Cheers Paul

[Hasie]

Dave
Where can I buy the LED strobes?

Jaco

[Learjet]

An update...

As promised, the manufacturer's sparky got in contact with me and clarified that the strobe unit is fitted with a microcontroller and mosfet switch as well as a schottky diode (as suggested by ZULU1). Their opinion was that the EMF was either a result of the wire cabling being to long, or of insufficient load carrying capacity.

I tested the LED strobes by connecting them directly to the battery terminal and the interference ticking in the headsets dissapeared completely (so that cleared the strobes as being the source of the problem)

Next step was to shorten the existing wiring by approx 1.5m which was achieved by relocating the placement of the strobes. When the strobes were connected I could still detect some feedback, but much less then before. I'll take it for a test flight as I suspect the ambient engine and wind noise may well cancel out the now much fainter "tick tick" sound. If not, next step is to use a bigger diameter cable to ensure adequate power supply to the strobes, try routing the cabling further away from the existing loom or use an alternate power take-off point altogether.

Have to say I'm very impressed with the brightness (lumen output or whatever it's called) from the LED strobes - better than I had anticipated

Thanks to everyone for their help. Jaco, I purchased the strobes directly from CN Lighting http://www.chrisnic.co.za

Dave

[nealet]

Hi
I am an Aerotrike Spirit which I have fitted 15Watt Xenon strobes, I also have a friend who has fitted LEd strobes to his RV7. I have had the ticking sound which I have fixed in mine and muy friends RV7 by fitting a local Voltage regulator inline with tge power circuit just before tyhe offending Xenon/LED strobe.
The voltage regulator is your typical LM338 adjustable voltage with with four additional components so that the output is set to 12VDC. The "active" nature of the internal circuitry in the chip gets rid of the noise and does not let it pass backawards to the rest of your avionics bus. It is a bit of a fag to make up a small setup, put in a small box and connect but it works. My strobes sit on the noes of my trike obvioulsy very close to me my radio and intercom, and it works well.

[Learjet]

Fixed Thanks for all the helpful pointers and suggestions. Drawing power directly from the battery and keeping the wiring length to a minimum pretty much did the trick.

[flying-i]

Dave

I always see that orange flightsuit long before any strobes are visual

[nealet]

Heh Heh! Thats why I wear it! I met a twin turbo prop directly above my field when I had just gone solo which kind of terrified me and drove me to those unusual "visual" lengths. We passed within 60m of each other, so now I make as load a "visual" shout as I can. Would rather look like a Christmas tree than a funeral pire !
Go Well