On my TB20 there is a JPC LED strobe on the tail and today I’ve installed 2 Whelen 650e LED strobes for the wing tips.
Since my G1 TB20 didn’t have a dedicated wire harness for the wing tip strobes, and I wanted them to start/stop at the same button press in the cockpit, I’ve connected them to the existing tail strobe (at the wire that feeds the tail strobe inverter).
Now there seems to be an issue, because whenever the tail strobe flash combine with the flash of the wing tips, the tail strobe momentarily turns off. Sometimes in the middle of the flash, if it happens for the wingtip strobes to start flashing just at that moment. When the pulses are intercalated (out of sync) there is no issue, both run ok.
Is there an issue with voltage drop when peaks combine or grounding that may be somehow corrected?
The system is a 12v one, the wingtip Whelen 650e draw 3.4 amps combined (peak) with no inverter needed, and the tail JPC one that uses an inverter draws 6.2 amps (peak). Actually it is rated at 75W/12V and hopefully I did the math correctly.
The positive wire that feeds both seems to be an AWG20 or AWG18 standard copper multicore twisted cable. The negative wire that feeds both is taken from the aircraft chassis.
Any idea on how to solve this? Thank you!
Sorry, I cannot help you with your question but as a fellow TB20-owner I was wondering: Are these strobes a straight-in replacement for the existing wing-tip strobes on a G1 or is some further work required to install them? Looking at the Whelen website, this product seems to also incorporate position lights.
No, there’s a lot of work needed in order to accommodate them, in place of the standard navigation lights. Hopefully a minor alteration in the logbook will be enough when my A&P IA sees it (N registration). Otherwise going the long, hard and costly way to certify it.
I have been testing Aveo LEDs. Not he same brand, but they definitely needs voltage, or they won’t strobe correctly (intermittent, or as you describe, they won’t sync properly). LED strobes are not really strobes in the correct sense of the word, merely very bright LED that require “lots” of amps in short burst. You need a good battery to make them work. Below approx 12 V (when loaded) and they start becoming erratic. They seem to be constant power devices (tested with a bench power supply), the lower the voltage, the more amp they draw, which doesn’t exactly help. I would check the battery first.
LeSving wrote:
I would check the battery first.
Maybe can you even run the strobes with the aircraft connected to grid power?
Following @wleferrand advice, I managed to power the aircraft from a 100 amps external power source, with no change. When they overlap, only the wingtip strobes work.
HOWEVER, as soon as I press the avionics button to start all the equipment, something strange is happening. Somehow, the 2 strobes magically always stay out of sync and flash one after the other, with no more issues.
I did the test several times. Avionics on, strobes always flash one after the other and work with no issues. Avionics off, the strobes timing starts to shift and, as soon as they overlap, the tail one is not flashing. Avionics on again, magically they somehow sync and flash only one after the other, no issues.
This is driving me crazy! The 2 strobe systems have no sync connection and do not communicate in any way. How on earth starting the avionics will always get them to flash one after the other?
The only thing that happens when I start avionics is a higher overall load on the battery, which should make things even worse…
I don’t mind the current setup, since I always fly with avionics on, however I don’t have any idea what happens, if any of you do, please let me know!
The two wingtip strobes should have an interconnecting wire, so they flash together. This is commonly discovered as the factor which dramatically increases the installation time of “direct replacement” LED strobes 
If they manage to flash together without such a wire then the other options would be
I would ask the manufacturer for their view because they have most likely come across this before.
An interesting experiment would be to connect a capacitor between the supply wire to the strobes, and ground. I would use something like 100 uF rated at 50V and +105 degC, in series with a 1A fuse in case it goes faulty. If it doesn’t do anything, add a 1uF 50V ceramic capacitor across it.
According to the IM local copy your strobes have a sync wire. What is it connected to?
The Whelen strobes have sync wires. The sync wires are connected together and to nothing else. There is no sync option for the JPC strobe.
The Whelen and JPC systems are totally isolated from each other, the only common thing is that both are connected (12V+ and ground) from the same socket.
I can understand there may be too much power when both strobes peak, I will try today to feed them from different circuits to see what happens. But somehow after I start the avionics they manage to always stay out of sync and it kills me I cannot understand what’s happening.
I will also try the ‘interesting experiment’ Peter suggested, hopefully the capacitor won’t blow up in my face :)
