Nothing comes up on google for TEPA. But then I am not searching in French 
This is one of the variants of the current sensing relay board used in Socata TB aircraft. This one was used in the GT and I think many earlier ones. The issue with LED landing+taxi lights is that they don't draw enough current to energise the relays (2.2A on these, 2.3A on the earlier hand-wound reed switch variant) and getting a more sensitive version of this relay would be a nice simple mod.
The rightmost relay (which does the pitot heat) switches at 1.6A so clearly they do a range of these.
Actually I suspect TEPA have gone bust. The relays have a date code of 50th week of year 2000. However Socata still quote a price for the above PCB - c. €800.
You are right they have gone bust. The company existed from 1977 to 2009. http://www.societe.com/societe/tepa-technique-europeenne-de-protection-et-d-alarme-309857795.html
Production of electronic components. Fabrication de composants électroniques.
The MD was born 1936 and it was closed by court due to inactivity.
That's fast work, mdoerr, very fast... if I ever owe you money I better not hide in France 
TEPA probably made loads of relays. The relay type needed is 1311, and there will be different current ratings under that P/N. The Ebay one is a normal relay with a 12V coil.
Actually everybody and their dog makes current sensing relays (google/images etc) but most are way too big. There is about 13mm height limit above the PCB. If one was going for a mod or an STC one would want a current component, too.
If you were really going for an STC surely it would simply be to dispense with the warning lights for the landing lights? They are totally superfluous anyway
Well, yes, I agree, but then any STC would need to include a means of reconnecting the wires which pass the current to the three loads. I suppose one could document three wires with crimped splices...
I have come across yet another version of this relay board, from another 2002 TB20GT, almost same as mine, but this board, labelled “1998” but manufactured around 1991 (!) uses different relays
Celduc does still exist – yet another French company (like many of Socata’s suppliers) which (like many of Socata’s suppliers) doesn’t appear to have any activity outside France.
The reason for the 15 ohm resistors is that the reed switches are too small to carry the inrush current of the incandescent lamps used in the panel.
So I think Celduc dropped that product, so Socata went for TEPA, and they went bust, so god knows where they get these bits from now. Clearly a French-only or French-if-at-all-possible sourcing policy comes with a big price/hassle tag. More importantly, should this policy change across the board in France, a lot of their industry is going to be on the slide very fast…
The reason for the 15 ohm resistors is that the reed switches are too small to carry the inrush current of the incandescent lamps used in the panel.
Wouldn’t a NTC resistor be better? That’s when I use when I drive incandescent lamps with reed relays.
It has been reported that Socata are working on an official mod for this current sensing module. I don’t know any more but it will probably be expensive (nearer to €1000 than anything else).
In the meantime I know a number of pilots of 28V aircraft have done a mod, which uses a high quality reed switch from RS Components (much more robust that those used by Socata) and a coil wound on a former. With care, it will carry the original 4A current too should somebody put the old lamps back in.
