mechanical turn signal blinker.
mechanical turn signal blinker.
(OP)
I'm curious about how a (not so) simple electro-mechanical turn signal auto blinker works.
The simple and incorrect answer, given by the how does it work sites, is a heater on a bi-metallic strip. This doesn't explain the blinker properties.
The blinker is in series with the load. A simple bi-metalic strip would have a shorter on time with more load (more current) and once open it would cool at a fixed rate so the off time would not depend on the load.
This would also delay the turn signal lamps while the bi-metal strip first heated up.
In fact the turn lamps are initially on and have shorter on and off times with less current (a single bulb instead of two).
Does anyone know how this actually works?
Thanks
Stephen Van Buskirk
A human being is a computer's way of making another computer. Yes, we are their sex organs.--Solomon Short (aka David Gerrold, US science-fiction author)
The simple and incorrect answer, given by the how does it work sites, is a heater on a bi-metallic strip. This doesn't explain the blinker properties.
The blinker is in series with the load. A simple bi-metalic strip would have a shorter on time with more load (more current) and once open it would cool at a fixed rate so the off time would not depend on the load.
This would also delay the turn signal lamps while the bi-metal strip first heated up.
In fact the turn lamps are initially on and have shorter on and off times with less current (a single bulb instead of two).
Does anyone know how this actually works?
Thanks
Stephen Van Buskirk
A human being is a computer's way of making another computer. Yes, we are their sex organs.--Solomon Short (aka David Gerrold, US science-fiction author)





RE: mechanical turn signal blinker.
http://auto.howstuffworks.com/turn-signal2.htm
RE: mechanical turn signal blinker.
RE: mechanical turn signal blinker.
Do like Mike, take one open and watch it work.
Good on ya,
Goober Dave
RE: mechanical turn signal blinker.
If one was really curious, one could probably look up the patent(s) for the feature on the USPTO.gov website.
RE: mechanical turn signal blinker.
I thought that was the way it should be. But was curious about why it increased frequency and decided to find out - aometime. I still haven't found out. So I am looking forward to someone finding out any year now.
If that fast blink feature is a later development, then later has a new meaning. Must have been more than 50 years ago.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
Bill
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"Why not the best?"
Jimmy Carter
RE: mechanical turn signal blinker.
There may be a clue in that the flasher modules, the little can-shaped modules of the sort used in North America, came in several flavours. The general application ones were either 2-terminal or 3-terminal types.
The simple 2-terminal versions of the simple bi-metallic strip design probably don't include the current sensing feature.
Here's an image of a 2-terminal version, with the "MAX6" presumably being the maximum numbers of signal bulbs. So it obviously wouldn't react to one of N being burned out. The DOT probably indicates the flash rate meets requirements.
The next step in this study would be to determine what's different between the 2-terminal and 3-terminal flasher modules.
Maybe that's the explanation, maybe not...
RE: mechanical turn signal blinker.
http:/
The 3-terminal versions are for those cars with a single turn-signal indicator light on the dash board.
But this detailed description also explains that a burned-out bulb has a different result than a faster blink rate.
RE: mechanical turn signal blinker.
RE: mechanical turn signal blinker.
RE: mechanical turn signal blinker.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
RE: mechanical turn signal blinker.
My observation is that the blinker on AND off times are faster with less load. I have tried to watch one and still don't understand it, though I'm sure it must involve heat dissipation, different resistors and materials. I was hoping for a specific explanation for no particular reason, just curiosity.
I was looking at the SAE specs. They call for a very narrow range of operating frequencies, +- 5 or 10%, as I remember.
Since blinkers can have more load (4 bulbs instead of 2) and still work, but blink faster with only one this must be quite complex. I did not find any allowance for faster blinking in the SAE specs but it's probably there somewhere.
Stephen Van Buskirk
RE: mechanical turn signal blinker.
My car puts a message on the dash (in any of several languages) telling me that a light bulb is burned out, exactly which one (*), and if it was able to reconfigure a nearby alternate bulb as a temporary replacement.
(* It fails to distinguish between the two rear license plate illumination bulbs.)
RE: mechanical turn signal blinker.
And I bet the CIA can also monitor every single lamp in your car on a big display screen back at Langley.
RE: mechanical turn signal blinker.
Daughter and son-in-law will visit tomorrow. He builds hot rod and vintage cars and will bring one of those devices.
We will cut it open, make photographs, push currents of different magnitudes through it and record the blinking.
It will be a major scientific undertaking and it will happen on a Sunday. I think it is worth while.
Stay tuned!
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
Keith Cress
kcress - http://www.flaminsystems.com
RE: mechanical turn signal blinker.
CERN's got nothing on you.
RE: mechanical turn signal blinker.
Thank you.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: mechanical turn signal blinker.
If the flasher normally runs, say, only two lamps and one opens, the heating coil will only be seeing 1/4th the power.
By virtue of them heating up slower and not blasting past the opening temp the coil also cools sooner to below the make-temp.
Keith Cress
kcress - http://www.flaminsystems.com
RE: mechanical turn signal blinker.
Looking forward to Gunnar's report!
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If we learn from our mistakes I'm getting a great education!
RE: mechanical turn signal blinker.
Test set up:
Variable DC supply.
Blink relay.
Adjustable power resistor to simulate different lamp loads (this will not simulate inrush, will find and use real bulbs if necessary).
Shunt resistor 1 ohm (lower part of load, actually) to measure load current.
Temperature transducer (miniature NTC thermistor fastened to representative part of heated member) to see temperature vs time.
Recorder.
Recordings will be made with different DC voltages and different loads and the relation between U, P, ON and OFF time, blink frequency plotted with U as the independent variable with one set of curves for each load setting.
If lamps available, the light output from them will also be recorded with an uncalibrated photodiode pick-up.
If lamps available, the UxI product (lamp watts) will also be recorded.
Anything else we should consider? Or any comments as to the feasability? And, above all, who will pay for this investigation? Remember that it is a Sunday, with double hourly rate.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
RE: mechanical turn signal blinker.
I done the initial measurements on a blinking device (UP-552.12V) and I must say that it doesn't behave at all as I thought or remembered.
First: The lamps are not at all on for the first second. Instead, there is a weak current heating the switch so that the lamps go on after a little more than 1 second.
Second: There doesn't seem to be any big difference in blinking frequency regardless of running with three, two or just one 21 W 12 V lamp (yes, borrowed a complete setup with lamps in reflector housing).
I will make the recordings available as soon as I have finished the beers and put them together in a pdf document.
Stay tuned!
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
If you open the packages up, the heating rate will be different due to now-flowing ambient air.
You need to reseal in transparent aluminum casing for a proper test...
:D
Dan - Owner

http://www.Hi-TecDesigns.com
RE: mechanical turn signal blinker.
And also when I replaced the rear lights with LED's, they also did not flash (The LED's are now somewhere else).
The emergecy flashers don't act that way. They will flash no matter what.
Strangly all these light bulbs have two filiments, and just the one burns out.
RE: mechanical turn signal blinker.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
Then any type of behavior is possible, absolutely anything.
RE: mechanical turn signal blinker.
Keith Cress
kcress - http://www.flaminsystems.com
RE: mechanical turn signal blinker.
Dan - Owner

http://www.Hi-TecDesigns.com
RE: mechanical turn signal blinker.
Result can be found on http://gke.org/arcus/ Look for document named "MEASUREMENTS ON AUTOMOTIVE..."
Now, hunting for the older type. The one that is ON from start and where blink frequency changes when load changes.
BTW: Any good explanation why heating current stays constant as filament resistance decreases during OFF period??
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: mechanical turn signal blinker.
I'm a little too frazzled (Monday morning headaches) to think straight about the constant-current issue, but your report's comment about the heater resistance rising as the lamp filaments' resistance falls certainly makes intuitive sense.
While you await an older flasher, I'll just throw out that my 1972 Pontiac Bonneville would just about double its frequency when I plugged in dad's boat trailer (approximately doubling the lighting load). However, it would simply stop on a burned-out lamp. This leads me to believe it had a single bimetal element perhaps.
Perhaps someone can countribute a make, model, and year of a vehicle whose blinkers sped up on lamp outage? That would help narrow the search.
Double good on ya,
Goober Dave
RE: mechanical turn signal blinker.
I am surmising that insufficient quantities of beer were consumed to arrive at conclusive answers. Recommend larger quantities be laid in prior to next weekend.
RE: mechanical turn signal blinker.
Good work. Mark me down as unsurprised.
Regarding "older"...
It's been my assumption that someone, way back in the depths of time, invented the bimetallic flasher of the perfectly simple sort you just tested. And I assumed that "later" someone figured out how to make a **NEWER** version that includes the 'operator feedback' about lamps being burned out. It would be illogical for this sequence to be reversed.
Obviously not all models would have included the extra feature even if it only cost a penny. My 1970s Chryslers didn't as far as I can recall. But that doesn't imply that it hadn't been invented even in the 1950s.
It should be a simple matter to order up an OEM flasher module, new or used, for any given car (even a 1962 Morris 1000) to check your recollection.
But once you get into the era of electronic modules (early 1970s ? for SOME models), there's no mystery.
RE: mechanical turn signal blinker.