Rear Window Flashers

With a possible continental tour on the horizon I decided that my usual reliance on hand signals and extreme road positioning would not be work well with me sitting on the kerb side of the car so I have fitted a couple of LED clusters in the corners of my rear window. These activate from the same connections as the semaphores. They are mounted on small pieces of celluloid sheet and secured to the window frame using the existing frame screws and yes, the rear blind still works without any problem.



A nice bit of safety kit there and looks quite unobtrusive.

Very nice!

Interesting they do not flash synchronously with the semaphore.

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My guess is that the rear window units have self-flashing festoon bulbs and those lamps are triggered by the switching function and not the flasher relay. I am looking at the addition of flashing semaphores for my cars (aka a WIP job; work-in-progress) and decided to operate them through the flasher relay so that all three are synchronised on each side.

With front and rear auxiliary flashers operating, the semaphores act as defacto side repeaters as on modern cars. Also, I was concerned that if there is a devilish rule somewhere that says flashing indicators have to flash synchronously, then at some inappropriate time, an authority dressed in blue might politely remind me of it.

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Yes, there is no connection between the flashing festoons in the semaphores and the three terminal flasher units controlling the rear window LEDs. The rear window LEDs don’t have any internal flash capability so each is connected to its own three terminal flash unit and receives its power from the switched supplies controlling the semaphore on its side of the car.


Aha! That explains it.

G’day Peter, I’ sure you need not worry about the boys in blue with the synchronisation of flashers, down here in Victoria Australia anyway. There is a regulation about the frequency of the flashes per minute/seconds etc., but not the synchronisation. Most modern cars used a single flasher can to regulate the flashes of all the indicators, hence they were all synchronised, but there was no requirement to be synchronised. Nik

Good grief… :slight_smile:

My original post about this wasn’t to raise any kind of an issue: I just thought it was interesting!

It’s interesting to me as well to see the semaphore trafficator flashing. I suppose you ran another wire to it and separated the two functions, bulb and lift magnet.
Mine just go on with the lift, don’t flash.

Nice to see the window shade too. I have only the left side spindle mount and the cord eye loops around the roof, haven’t seen anyone offering the spindle ends and shade.

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The flasher units are of a type specifically for LEDs and if I did have a problem with the law it would only take a couple of minutes to disable them but I don’t really foresee this happening. The flashing LEDs in the semaphore arms are available commercially and are a simple bulb replacement with no wiring involved. 12v Self Flashing 36mm Semaphore / Trafficator Amber LED Slimline 256 – Classic Car LEDs Ltd

Classic Dynamo & Regulator Conversions (

See: (LED Lights)



Is there a source for these flashers in the US?

I bought the flasher units from amazon UK

and the LEDs clusters from eBay

There are quite a lot of different configurations of these LEDs. Many of them have the flashing function built in and offer various flash rates controlled by a third wire. I deliberately avoided these because I was not convinced that they would remember the flash rate that I had wanted and resetting them would be difficult. So my LEDs only have two wires, positive red and negative black.


I’m very interested in the flashing semaphore/ trafficator bulbs sourced in the US. I’ve searched the internet but only find them in the UK or Australia.

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I guess you never used festoon bulbs in trafficators in the US.


Well, festoon bulbs do exist here, even LEDs, but they don’t flash.

No US cars ever had trafficators that I ever heard. Just British imports here up to about 1948; after then it was all flashers.
In the 1920s there was an aftermarket device called a Wig-Wag for signalling a stop. It waved from side to side. I suppose you could signal a turn or lane change with it.

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Fun rabbit hole to drop into. Looks like there were some aftermarket US semaphore signals. Interstate-State Auto-Signal with 1921 patent:

VW used trafficators too up to the '50s before flashers, but I don’t know how many other European countries had them, or which companies made them.

My 1955 DKW had them. Early Volkswagens also had them, I believe up to 1952.

Just another thing to remember, the festoons need to be slim enough to easily slip into the housing. There are many advertised for suitability for trafficators but they can be a bit too large in the diameter. Though you can push a wider festoon into the arm, if it is a squeeze and puts pressure on the side walls, it may eventually damage the plastic by constant side pressure, or even heat from the bulb. These plastics are now very old and it would not take long for stress cracks to show and brittleness to develop.

Unfortunately, the SF54 and SF55 8.5" arm models are extremely rare and if you break one, that could be the way it stays.

Yes the festoons need to be able to move freely in the vertical sense or the spring electrical connection on the bottom will not create enough pressure for good contact on the chrome top connection. If you end up buying ones with too large a diameter of end caps for free movement I found that you can squash them gently to get a proper fit.