1936 Terraplane add-on turn signals using NOS switch

[jaycoop]

Hello all,  I followed the attached schematic, except am using 6 volt relays, in conjunction with an NOS 1940s column-mounted lever switch.  When switch is activated, the turn signal lights glow solid.  I've tried different flasher units, so that's not the problem.  I found this schematic on-line about 10 years ago and now can't find the source.  Any troubleshooting ideas or criticism of the schematic?  Thanks!

[Bloo]

As shown it should work.

 

Let's look at one side. Turn on the right side signal. I am assuming no semaphores. Relays R=R1 and R=R2 have their coils connected to 6V and ground. The switch contacts inside them disconnect terminal 30 from 87A and connect it to 87. R=R1 connects the right front bulb to the flasher. R=R2 disconnects the right rear bulb from the brake light switch and connects it instead to the flasher. Now we have 2 bulbs connected to the flasher. That is exactly what a modern "7 wire" turn signal switch does.

 

4 hours ago, jaycoop said:

Any troubleshooting ideas or criticism of the schematic? 

If we want to split hairs, by the old German numbering system these terminal numbers come from, they have 85 and 86 reversed. It makes NO difference though. Zero. That detail is pretty much ignored today. It isn't even worth reversing them to try. It works equally well as shown. 

 

4 hours ago, jaycoop said:

I've tried different flasher units, so that's not the problem. 

It basically has to be the problem on some level. The flasher is the only thing that flashes. If it is a traditional thermal flasher, the current drawn through it by the bulbs connected makes it flash. It sits there *not* flashing until you connect bulbs to it. On the old originals, the flashers had to be matched to the number of bulbs. Otherwise they flashed at the wrong speed or didn't flash at all. Later on there were "heavy duty" units that were less sensitive to the number of bulbs. They still needed the current draw, it's just that if a bulb burned out or if you added one temporarily by plugging in a trailer it would still probably sort of work. Electronic flashers may not care that much about how much current. Some of them may need a ground. The old thermal flashers did not need or use a ground. LED bulbs, if used, draw almost no current, so they won't make a traditional flasher flash. Those generally require a special electronic flasher.

 

Speaking of bulbs, I am going to have to make the wild assumptions you are using a traditional thermal flasher for a 6 volt car with 4 bulbs, and that your 4 bulbs are incandescent, and the flasher is either "heavy duty" or sized for 2 bulbs. 2 bulbs because only one side is on at a time.

 

By the way, these are bright bulbs that run hot. Original brake light bulbs should be fine, but little 1-1/2 candlepower parking light bulbs used in front on many antiques hardly draw any current. The front bulbs need to be roughly equivalent to the rear electrically. If you used those teeny bulbs or some LED to fit the available sockets in front or for clearance or to avoid melting a plastic(?) lens, you would need to be using a flasher that can flash with only one (rear) bulb. In that case the front doesn't draw enough current to count. Maybe an electronic flasher would work.

 

If you are keeping the park light function, the sockets and bulbs in front need to be changed to dual element. If you keep using single element bulbs in the old parking light sockets, you need to disconnect them from the old wiring completely.

 

Bad grounds reduce current. All four corners of the car need good grounds.

 

Edited December 13, 2023 by Bloo (see edit history)

[jaycoop]

Thank you for replying!  Yes, I'm using traditional incandescent bulbs and thermal flasher.  The 3 different brand flashers I tried make a click sound, as if wanting to function, but then stop.  Maybe an electronic flasher would work?  I wonder if the relays are somehow preventing the old-fashioned thermal flasher from doing its normal thing?  I have double checked for good grounding.

[TerryB]

Does your NOS switch have any corrosion on the electrical contacts that might be limiting the current flow?  You could check that with an ohm meter. 

[Bloo]

Well... everything points to the flasher(s). Before buying something else, you could get a couple old sockets and hook 2 bulbs in parallel.

 

6V Battery(+) >> Flasher(X),      Flasher(L) >> paralleled 2 bulbs (wires),    Sockets of paralleled 2 bulbs >> 6VBattery(-)

 

If the flasher is good, and is appropriate for 2 bulbs, the bulbs should flash. That takes the swtich, relays, car, wiring, grounds, etc. all out of the picture.

 

I've got a sneaking hunch it isn't going to flash.

 

Edited December 13, 2023 by Bloo (see edit history)

[Oldtech]

37 minutes ago, jaycoop said:

Thank you for replying!  Yes, I'm using traditional incandescent bulbs and thermal flasher.  The 3 different brand flashers I tried make a click sound, as if wanting to function, but then stop.  Maybe an electronic flasher would work?  I wonder if the relays are somehow preventing the old-fashioned thermal flasher from doing its normal thing?  I have double checked for good grounding.

I don't see the relays having anything to do with no flash, they energize when the lever  has selected and stay that way until turned off. 

[TerryB]

Yes, see that now, the turn signal switch is just a relay on / off.  

[jaycoop]

Wonderful, thanks for more good feedback...so the relays are not likely the issue.  I will try that good idea of making a small circuit with spare sockets.  I have some.  I can see where it will help narrow things down.  I'll also make sure the switch contacts are good/clean.

[jaycoop]

OK, got it figured out.  The system worked fine with the mini circuit, and I used the flasher marked "Heavy Duty 535".   So I went back and triple checked the wiring and grounds.  It was a poor ground, my fault.  Thanks again for the help and the insight into this system.  It's a great way to employ a vintage 3-position switch, as long as you have a place to tuck the relay assembly out of sight.  ☺️

[jdome]

I am probably late to the party but I do have a couple of criticisms of the OP's schematic as drawn.

First criticism is that the 87A terminals of relays L1 and R1 are not utilized in this drawing. With the schematic, as drawn, you can use your original front, single filament bulbs for both parking & turn signal. The park filaments must first be disconnected from the original park circuit and properly wired to the relay system. Then run a new wire from the park light switch to the open 87A terminals of L1 and R1. The L or R park light will flash properly whether the park lights are on or off.  The 7-wire turn signal switch does not have this provision, although I suspect it may have similar internal unutilized contacts that are not wired up as supplied by the factory.  I plan to add a switch to my latest car  and I will open it up to see if the switch can be modified to function with single filament park bulbs. I still prefer the aftermarket trun signal switch, even if I have to modify the park sockets for 2 filament bulbs.

 

Second criticism is that the relay system (as drawn) is more complicated than it needs to be and complicated to trouble shoot.. I don't know why but who ever drew the schematic thought it necessary to pass the flasher voltage through the #1 relays to  the #2 relays in order to make the rear lights flash.  I redrew the schematic provided by the OP to include some changes & simplifications. It should be easier to install. I also incorporated the park light circuit. My relay system provides for the use of single filament bulbs for front park and turn function and one filament of the rear bulbs for brake and turn functions. Your original tail lights use separate filaments on a separate circuit and does not need modification. My relay drawing will work with 6 or 12 volt + or - ground provided you use the proper voltage componnts for your car.

[Frank DuVal]

But, parking lights are small candlepower lamps, so they will not make the flasher flash. If you put large candlepower lamps in the sockets then the parking lights will be too bright! This was the OP's issue, bad grounds made too little current flow in the system for the flasher to flash.

 

As to simpler, tomah-toe, tomah-tah. Yours may be easier for ladder diagram thinkers. Both work. 30 amp relays, no overloading of contacts for one relay to handle two lamps worth of current. Now you need to redraw it to remove the complication of the parking lamp circuit, since it won't flash that way. 😉

 

It was good to remove the Semaphore wiring, as that is a European electromagnetic thing.😁

 

🦃🍠🍲 🕎 🎄 🎄

[jdome]

Thank you for the compliment, Frank, I think, on my simplistic "ladder diagram thinking."  Simpler is always better in my opinion. Yes, if wired properly and working they both do the same thing only different.  The difference is that I made the circuitry and drawing easier and cleaner for the novice to understand what is going on.  And in reality all I did is correct a poor design by connecting all relays directly to the flasher, remove the jumpers between L1 and L2,  and R1 and R2 relays, and connect the front bulbs directly to their associated relay.  My circuit is inherently more reliable. Failure analysis will shows the weaknesses in the original design:

 

ORIGINAL DESIGN

Left turn sw on, Relay L1 fails to energize :  Front left turn bulb = DARK. Rear left turn filament = DARK.  apply brakes = Rear left brake light DARK (until turn sw deactivated).

 

REVISED DESIGN

Left turn SW on, Relay L1 fails to energize : Front left turn bulb = DARK.  Rear left turn filament = BULB LIGHTS UP in normal flasher function but the single bulb load may not cause the flasher to blink so it may be on solid. Apply brake = no effect because the left rear light is powered up in normal turn mode but likely not blinking, so it appears as left BRAKE LIGHT ON.

 

A failure of relay R1 will produce the same results on the right side.

 

If you don't want to use the single filament park lamps for turn function then don't connect them to the circuit.  If low CP load on the flasher is the reason, you could use higher CP bulbs or you could add load to the flasher by connecting an indicator bulb to the #30 relay terminals connected to the rear bulbs. That will increase the flasher load and provide left & right flasher indication as well as brakes on indication.