WHAT MAKES IT WORK? #14 Turn Light Flasher "WHAT MAKES IT CLICK" tubalcain

Did you ever wonder how a signal light flasher on your car worked?
Be sure & watch all the videos in this series,

[@michaelmurray9154]

That little metal piece that bends with heat is called a bimetal. Two pieces of metal with different rates of heat/ expansion laminated together. When heated, one expands more than the other causing it to bend. Same technology used in the thermal trip side of most circuit breakers. Neat video Pete!

[@stefantrethan]

+Michael Murray "Bimetal" refers specifically to a strip made of two layers of different metals sandwiched together. While it is true that this is used in breakers, and thermostats, and many flashers, if you look closely you will see it is not the case here. The strip with the heating wire around it is spot welded on the two ends to the larger spring. As the strip heats it expands, causing the spring to click over. It just relies on the lengthwise expansion of the metal compared to the cold spring rather than bending from different expansion of dissimilar metals in a bimetal strip heated to the same temperature. The difference is subtle, but important.

[@mrpete222]

+Michael Murray Thanks for watching

[@mrpete222]

+stefantrethan You are right on--not bimetal

[@pierresgarage2687]

Brings the feeling of those 1950's cars where the whole body was vibrating when the flashers were actuated, every piece of steel in those cars were welded solid together, so the KLUNK was really loud... My first memories were my dad's 1953 Pontiac... ;)

[@jayminor9757]

Thanks Mr. Pete. I'm 61 years old and have been a helicopter mechanic for 40 years so figuring out mechanical things is in my nature but you just taught me something that I've wondered about on a few occasions. Hopefully age will never prevent me from learning new things. Carry on please, sir!

[@umxrr8677]

You must be 65 now, how are you doing sir

[@grantlesueur]

Nice video thank you- Im replacing the turn signal lamps to LEDs on my 61 Chev. This is why I have to also upgrade to a solid state flasher for LED as LEDs do not impose enough load to allow the mechanical fisher to work properly. This was a good refresher to remind me why this is necessary.

[@roberthorner8494]

MR. PETE, IT IS INTERESTING TO NOTE THAT LIONEL TRAINS USED THAT SAME METHOD TO BLINK LIGHTS ON SOME OF THE ACCESSORIES. IT WAS ALSO USED TO RING THE BELL IN SOME OF THE TENDERS. GREAT VIDEO, THANKS.,

[@mrpete222]

+ROBERT HORNER Interesting--Thanks for watching!

[@suzukichopper]

From what I've seen over the years, there's not a lot of people who have ever even heard the click of the flasher because they NEVER use their turn signals!! P.S. Love the What Makes It Work series!

[@mrpete222]

+suzukichopper LOL--thats the best one yet--Thanks for watching

[@JDMHaze]

bmw

[@MarioDallaRiva]

So interesting, Thanks!! Great closeups. 👏🏻

[@Info-Tech-]

Sir you are the best teacher!. Thanks

[@mrpete222]

😀😀😀

[@stanleydenning]

The spring that changes shape is called a Bi-Metal spring. It is a sandwich of two layers of different metals. Different metals expand and contract at different rates and at different temperatures. When the element heats the spring, one side expands faster the other, causing it to warp.

[@mc_cpu]

This is an excellent series. Thank you for making them.

[@EugeneKhutoryansky]

Great video and thanks for making it. But, I think that at about six minutes into the video, you may have said it backwards. I think the heating element heats up when the contact is closed, and cools off when the contact is open. When the contact is open, no current can flow, and hence the heating element can't heat up.

[@Mr62Butch]

+Physics Videos by Eugene Khutoryansky I think there are two different configurations and his various cut opened examples show both. BTW the older designs had three prongs. The heater circuit was somewhat separate. Missed his six minute explanation.

[@EddieTheGrouch]

The old style flashers worked that way (like a thermostat) and started in the ON state but they had some shortcomings: 1. They had to be matched to the current of all the lamps to get the timing right. Say your car has 4 lamps per side - one lamp fails and now there's not enough current draw to heat the bi-metallic strip and open the contact. This lights stayed on and no flashing occurred. If you added a trailer so you now had 5 or 6 lamps per side, the higher current draw heated the strip too quickly and the flasher went too fast for the lamps to reach full brightness. 4 lamp flashers were very common; front, back, and 2 side markers. If a designer wanted to deviate from that he/she had to play with the lamp size to stay within the flasher's range or use a differently tuned flasher. 2. Making and tuning bi-metallic strip flashers was a bit fiddly and took skill to get them all flashing at the same rate like the designers wanted. To get around all that the bi-metallic strip was eliminated and a low current heater was connected across the terminals full time. Now the flasher could work with only 1 lamp or 10 - as long the circuit was completed the heater would operate. A spring steel snap acting switch replaced the bi-metallic strip. The switch is bent back away from the contacts and a small splint (lack of a better term) is attached to hold the contacts open. The heater coil is wrapped around this splint. These flashers start in the LAMP OFF state. The heater causes splint to expand allowing the spring contact to close and light the lamps. While closed, the heater is shorted and all the current goes to the lamps. When the splint cools it shrinks and pulls the contacts apart and repeats the cycle. Remember back when we'd manually flash the signals to make a lane change? The lights came on as soon as we nudged the lever as we had the old style flashers. Then somewhere along the line they no longer did that (new style flashers) and we had to hold the lever until it started flashing on it's own. This caused accidents as folks used to doing the quick flash were changing lanes not realizing the flasher hadn't started yet. I think it was around this time that many people stopped using flashers altogether as they couldn't be bothered to wait that 1 second for something to happen.

[@EugeneKhutoryansky]

+Eddie the Grouch, in the particular example shown in this video, the flasher only has two terminals, and it is connected in series with the light bulb. Therefore, I think it has to be one of the old style flashers, as there is no way that the flasher, in this configuration, can simultaneously interrupt current flowing to the light bulb, and still have a closed loop for current to flow through the heating element.

[@robehickmann]

+Physics Videos by Eugene Khutoryansky could the resistive heater be connected in parallel, passing current through the light but not enough to notably light the lamp?

[@EddieTheGrouch]

The clue is in what state the flasher's switch is in un-powered. If the switch is closed, the heater is in series with the switch and merely replaces the function of a bi-metallic strip. All the lamp current must past through the heater and the total lamp current can effect the flash rate. I called this the "Olde Style" or type 1 flasher. If the switch starts in the open state (as in the close-up example), the heater is bridged across the terminals in parallel all the time. The high resistance heater only needs a small current to operate and itself passes only a small current to the lamps, not enough to light them, while the flasher switch is open. Once the heater operates and the switch closes, the heater stops because the current flows through the lower resistance path of the switch. The heater is effectively shorted out and ignored. This why the number of lamps has little effect on the flash rate. When the heated strip cools and retracts the switch, the current has to flow through just the heater again and the cycle repeats. This I call New Style or type 2 flashers.

[@stevew270]

Cool, now I know what that little tunk noise is with the blinker on! Thanks!

[@metalmoto]

As I remember, J.C, Whitney used to sell flashers that played music. Like a portion of an Elvis Presley song. So you could hear it better...

[@mrpete222]

+metalmoto They sold a lot of novelties

[@infoanorexic]

I'll keep the idea of moving the flasher unit out from under the dash in mind. Tinitis and road noise won't let me hear them anymore. Too many hours on an old Cats with loose decking plates and un-muffled pony motors. As a young man, I spent a day running a series of errands with my Father. One task took us by where he worked at the rail yard. At the board marker's office he met one of his peers, Mr. Raymond "Ollie Dolly" (as the female clerks called him) Oliver. They hadn't seen each other for a while, so there was the usual greetings and exchange of news, part of that was about the recent influx of new 'kids' (switchmen) and how 'green' they were. Ollie asked: "Kenny, do you remember when we looked across the yardmaster's desk and thought 'when is this old prune-face going to retire?'" Dad nodded. "Now we are the prune-face." and now I are...

[@wertbe1718]

Very informative and helpful!

[@mrpete222]

Thanks

[@TheIanmurphy]

Really great explanation / demonstration. Any idea what can cause one of these to go bad? I had two go bad in the last month. My signals would just stay on all the time instead of flash

[@rongarza9488]

At 7:20 he touches the hot coil and it reminded me of an episode. My family -- my wife, son, 2 daughters, and me -- went out to supper. When the waitress brought our plates, she told the us all, "Be careful the plates are hot." The older girl told the younger girl, "Don't touch the plate, it's hot.". My son touched his plate and exclaimed, "Dang, that's hot!". And that, my friends, is the difference between a boy and a girl (although girls are finally catching up).

[@mrpete222]

That's interesting

[@rongarza9488]

It would be interesting to see how many women have posted on KZbin compared to men. BTW, thanks for posting this.

[@koraypekericli]

Wow I was curious about these! Thanks for this clear explanation. K.

[@rusty7989]

I must say I am enjoying your You Tube videos very much, especialy the 'how it works' ones. I always wondered about that coaster brake. Where could I find out about cutting multiple threads?

[@infoanorexic]

+Rusty Stebbins He's covered that, just look back through his other videos...

[@farerse]

i had no idea.. i was thinking these flasher relays had more electronics inside them rather than this "simple" mechanical mechanism

[@thomasbr93]

Always wondered how that worked. Thanks!

[@benelevate]

Thanks Mr Pete

[@HamWithCam]

Nicely done!

[@ivanpetrov4917]

Thank you for the great explanation! :)

[@sparkmencer]

My only disappointment was when you disconnected the still-hot wires from the working flasher setup (4:51), and laid them down, they didn't touch each other and create the world's smallest fireworks show, as they most certainly would have done for me...your comments would have been fun. I'm a BIG fan, Pete, and always look forward to the email notice about your newest video being ready for viewing...thank you for being who you are, and for doing what you do.

[@deakzoltan2714]

@mark spencer I see this is an old comment of yours, but maybe you still will read my response. :) This went through my mind too, but in fact, only the light would be turned on, if the two leads had touched each other. So no fireworks, because that would not have been a short circuit. :)

[@DougFrantz]

You're old. Yet you make a better video than most folks can produce! Seriously good work. Thank you #subscribed #sorryidrankwhiskey

[@mrpete222]

Thanks

[@sunnymango2101]

Great explanation. Thank you! Can I wire something to my turn switch without turning off with the relay turning on and off (light blinking)

[@dougrundell947]

And wearing black socks with leather sandals. .

[@mrpete222]

+Doug Rundell True--almost to the knees.

[@gusdogbrownlab435]

Good stuff..thanks

[@elsdp-4560]

thank you for sharing.

[@mrpete222]

+ELSDP-45 Thanks for watching

[@blackpup3624]

Great Video!

[@PixieSpright]

But I'm trying to undertand: why would the steel strip ever cool off if the current keeps flowing continually into it?

[@bandogbone3265]

When the contact point on the steel strip touches the stationary contact point (which closes the circuit to turn on the light), the heat accumulated in the steel strip drains through the contact point into the stationary piece of steel more quickly than heat accumulating in the heating coil, so the steel strip cools and returns to its previous position, thereby opening the circuit, and the cycle repeats. Also, I'm guessing the resistance through the heating coil is greater than the resistance through the bulb, so when the circuit is closed, the electricity prefers to flow through the bulb rather than through the heating coil, which also allows the coil to cool down. When both front and rear bulbs are ok, you get a nice slow repetition rate, but if one of the bulbs burns out, the repetition rate increases, because the resistance through the bulb pair increases (the bulbs are connected in parallel, and the resistance through one of the bulbs goes to infinity), so more current continues to flow through the heating coil, so it does not cool as thoroughly as when both bulbs are working, so it breaks electrical contact sooner, so you get more rapid cycling, which alerts you to the fact that one of the signal bulbs is out.

[@deakzoltan2714]

The key is, the current does not flow continually through the heating coil. The process is like this: The heating coil is permanently connected to the two outside connectors of the flasher. When the indicator light switch closes the circuit, the current starts to flow on the heater coil, but this is a relatively low current (say 100-200mA), which is not enough for the bulbs to light up. They have a relativeley low resistance (a few ohms), while the heater coil has a higher value (say around 50-150 ohms) to reach the mentioned current. So at first the heater coil starts to heat up, and the bulbs dont do anything. As the temperature of the small steel part is rising, it is expanding in length, and starts to bend the other larger part of the swithching mechanics. When the switching point is reached, the contacts are closed. At this point the heating coil is shorted by the contacts, so there will be no more voltage on the heating coil, and of course no more current either. This is the main reason why the heated part starts to cool down. Because there is no heat supply any more, to override or compensate the heat loss coming from the risen temperature. At the same time, as the contacts are closed, the bulbs are not "powered" through the high resistance of the heating coil, which was not enugh to power them up, but directly through the closed contacts with no resistance, and so the current starts to flow on a higher level according to the resistance of the bulbs. Then in the meantime the smaller steel part is cooling, and contracting, pulling the larger plate back. With decreasing temperature it will reach a point, where the increasing pulling force is enough to turn the larger plate back in the off position. And then the cycle starts all over again.

[@edsgunsmithing3098]

this experiment sound like a good excuse for buying an IR camera.

[@militech9]

Wow what a fantastic video! This is how you make a proper video on how something works.

[@mrpete222]

Thank you very much!

[@kendallh9106]

The strip of metal he's referring to is a bi-metal. Two different metals are sandwiched together to form the strip. Each metal expands at a different rate, when current is applied, which causes the strip to flex...hence, opening the circuit. Once the strip cools off, it regains its original form (closing the circuit) and the process repeats.

[@nixxonnor]

Nice video. I troubleshooted a similar flasher (turn signal relay) a few decades ago when my 1962 VW beetle was acting up. The flasher in my old VW even had an adjustment screw to adjust the on/off time ratio (IIRC).

[@Kirby444]

I've got a 3-prong thermal flasher, and just tried hooking it up to a 12v power supply. Smoke came off the tiny wire! I wondered if I had it wired backwards, so switched my wires around. Again, more smoke, and still no clicking. Any thoughts on what I am doing wrong? I don't seem to have burned anything out yet, but I think I am close. Smoke is never good.

[@nicholaswheatley8102]

Thank you a very helpful and informative video!

[@serchmarc]

and the video of the electromechanical?

[@CarterWHern]

Nice.

[@mrpete222]

+Carter W Hern Thanks for watching

[@brianchristine9301]

What a great video! Thank you so much for making this. Very helpful and interesting

[@MattExzy]

Well I be darned... all this time, I always thought it was a relay clicking, not a metallic strip. I wonder if some are relays? But then I'd imagine a relay wouldn't last as long given the duty cycles involved..

[@kevCarrico]

not just an "old person" issue -- same applies when radio is cranked by kids. how about visually checking the instrument cluster a few times a minute as we were taught in the old days?

[@johncase2974]

Greetings, I have a question for you. I’m trying to make a DIY European style two-tone siren using car horns and need a flasher capable of handling the task. I’m using two Seineca horns, one at 335Hz (3.0 amps) and the second at 435Hz (3.0 amps). Any suggestions ?

[@Mi_Fa_Volare]

Ate those things mandatory? Because I still hear the clicking in modern cars. As if other forms of circuitry is not allowed.

[@iand8121]

For some reason I really like the speed of the flasher at 8:48. Just like the ones in the older Chevy Colorados/GMC Canyons.

[@Mike-ms8uq]

Great video

[@romeparrilla8307]

HI THERE,GOOD VIDEO',I HAVE THIS 1979 KAWASAKI KE 100 ENDURO,I REPLACED THE REGULAR SIX VOLT TURN SIGNALS WITH AN LED SIX VOLT TURN SIGNALS.WHEN I SWITCH TO THE LEFT,ALL 4 BULBS ARE FLASHING,SAME WAY TO THE RIGHT.WHERE DID I GO WRONG?PLEASE GIVE SOME ADVISE.THANK YOU

[@jonlogan8171]

Very cool. Thanks for another great video Mr Pete. In your playlist for "What makes it work" there are 4 more videos that are [Private video], and therefore not viewable. Wasn't sure if you are aware of that. If you have 4 videos that aren't getting any views, that would be the reason. Don't misunderstand, this is total selfishness on my part. If you have made other videos, I want to see 'em!

[@StrongEnough78]

The 552's are too quiet. I like the old 323's better. Those are getting harder to find now. I had to order one through ebay a while back when mine went out. And today I went and scrounged some older model GM's in the junk yards and managed to find a couple that were easily accessible and still worked. I may go back this weekend with some tools to get the ones that are further up behind the dash.

[@willshankle8527]

Thanks for another great video. I'd like to add that I solved the problem of not being able to hear the "click" by wiring a seat belt buzzer in series with the flasher thus making an intermittent "buzzing" sound. It was just obnoxious enough that I never again forgot to cancel my turn signal. :)

[@mrpete222]

+Will Shankle good idea

[@1musicsearcher]

They're made louder on purpose? I've wished it was silent. Sitting, waiting to make a turn, that clicking sound is just annoying. I could never figure out how anyone could drive along with a blinker running and not see that flashing light on the dash.

[@RightOnJonCrane]

Great video! Thanks Tubal Cain! How about taking apart some circuit breakers. Maybe square D QO? I just replaced a bunch in a panel that was overheating from bad breakers.

[@mrpete222]

+CRANEDRUMS Believe it or not, breakers are on my to do list.. I'm so cheap, that I'm watch for used ones

[@thereve]

Hrm, perhaps this explains why the turn signals on my old motorsickle just burn solid and won't flash. Either the relay is seized up or it isn't getting enough current to heat up sufficiently to cycle.

[@davida1hiwaaynet]

Very nice! I have found out that the original General Motors flashers are irreplaceable. The aftermarket ones don't work the same and don't sound the same. Therefore, whenever I am at the junkyard, I collect original GM ones for my project cars.

[@mrpete222]

+davida1hiwaaynet Thanks for watching--resourceful

[@bandogbone3265]

Thanks, so it's just an oscillating switch, not truly a relay. I guess it's called a relay only because it typically sits alongside other similar-looking modules in your fuse box that actually are relays. Mystery solved!

[@W4BIN]

I think he should have demonstrated that special loud flasher module that he bought, but didn't work in his car. It could be defective. ???

[@bernardocisneros4402]

I don't care for the new electromechanical or solid state ones. The old thermal ones were very reliable and inexpensive. If it ain't broke don't fix it. Some newer cars come with the flasher integrated into one of the electronic modules.

[@ricksmith7631]

the newer ones, newer than the thermal ones use a condenser. the condenser stores a charge but takes some time to be filled, once its filled the relay can switch to drain the condenser thru the tail lights, once the charge is drained the relay opens and power is then allowed to flow into the condenser which takes time to fill before energizing the relay and allowing the turn signal to light. these work good with incandescent bulbs but not so well with led bulbs, the interval is longer since led's take less power to light. also if a bulb burns out you have a slower flash rate. once thing i noticed is that when you turn on your 4 way flashers, the flash interval is somewhat faster.

[@Landrew0]

I would have mounted a "sugar cube" buzzer, and tapped it into the signal circuit.

[@balisticsquirel]

So American cars' indicator lights flash faster in colder weather?

[@mrpete222]

+balisticsquirel Thanks for watching

[@thanestevens3157]

My turn signals have been out for 4+ months I always worry about getting into an accident.

[@davidmatthews5805]

Excellent video. I have a three prong flasher and was curious what the third prong is for.

[@MrGunPilot]

I bought an aftermarket "loud" beeping flasher for my toyota tundra, but I wish I could find the "old school" style from the 60's that really sounded off with a double click. Anyone have any ideas to make the clicking louder??? Another Great video Mr Pete.

[@mrpete222]

+GunPilot Thanks for watching

[@sirphew4941]

Why do I feel like MrDressup is making this video 😂

[@FilmMastersChannel]

The old ways are still the best ways in my opinion. Great display and helped me with my 1971 HQ Monaro.

[@mrpete222]

Thanks

[@Crazygaucho62]

Lincoln town car makes a noise if you leave them on for too long….don’t ask how i know….

[@Tbolt1000TForLife]

I had a 1990 Plymouth Acclaim LE and it had a very unique flasher. The hazards and turn signals each had their own sound. The turn signals had kind of a "drum like" clicking sound, the hazards sounded similar but still different. Anyone know what type of flasher it was? And if it may have been 2 separate flashers? Thermal? Electro-mechanical?

[@fendyboi404]

in my dads old truck blinker didn't click

[@MrUbiquitousTech]

Great video Mr. Pete! Very enlightening for sure! Interesting, at 6:46 it looks like the soldered connection in the upper left is liquified! I know it can't be so it must be a trick of the eye, but it really looks like the solder is moving in liquid form.

[@stefantrethan]

+ShysterLawyer Ha, it really does look just like that. In HD you can see it's just a reflection and the wire is actually spot welded there.

[@mrpete222]

+ShysterLawyer Thanks for watching

[@dariomendoza191]

pretty cool Thanks for Sharing!!!

[@stevenwood7959]

put 1157 led bulbs in older car flasher will not flash.

[@milliejain8645]

Please tell me sir what happens if we dont use indicator flasher relay

[@Thunderbird1968]

Lol very specific description of old men

[@tttco]

Thanks for teaching me.

[@Fatamus]

You touched upon a good question; how does the complex turn single switch work? The opposite break light canceled by the turn single was a tough one to figure out.

[@davidpruyne7340]

Some were fastened to a piece of tin ,, made them more audible to hear

[@Watchyn_Yarwood]

I think I found your lost pointer: kzbin.info/www/bejne/p2jEfZyDea2EqK8m47s

[@davew368]

+William Garrett Took me a sec to see the name...pretty cool. MrPete is the man.

[@gmisltr]

I really enjoyed watching this, and I have a question, I have a 78 gmc tiltwheel pickup, its been shall we say, upgraded to what ever fits the owner at the time, its rusty, but I had everything working well, Then the blower motor seized up, so I installed a new one, and it would not work, I had to hot wire it from the fuse box, and then found out the turn signals wont work, I checked bulbs, and wires, and put in a new switch, and still, they dont work, I have power going into the switch, and the 4 ways work, and running lights, and brake lights, but no power coming out of the switch, for turn signals?, I tried 3 different flashers as well, Ground? bulb?. why would both heater fan, and signals stop together?

[@nothingbutjets941]

Great video and education... Thanks!

[@fritzfromswitzerland]

I connected the blinker to a speaker and now i can hear it even if i'm deaf

[@brucherrin8947]

Clenching their rotten teeth around a soggy cigar 🤪good one

[@wirechair]

I always wondered about it but finally looked it up. Very interesting. I always just thought the car sound system was playing the ticking!

[@mrpete222]

Interesting!

[@Shintirawi]

Like the way you explained it. Thank you

[@OnlyTheEd]

Thank you for teaching this old (well.....56 year old) man something he didn't know.

[@beakittelscherz5419]

tehheehe ..frankenstein lightbulb switch

[@stevenhoelderich9490]

Thank you, I really enjoyed, that!!

[@shanek6582]

I had something wrong with my truck flasher and it started going twice as fast but still worked, my buddy said it was a short and fixed it but I never knew exactly what went wrong.

[@mrpete222]

+Shane K thanks for watching

[@Tryin2FlyII]

Pretty Neat!!! Never gave much thought about that annoying little switch lol Nice to finally see what is in there mystery solved Thanks !

[@jacquesfrancois2033]

Wonderful video thank you Pete

[@daki222000]

The ones I know work with a coil and a condensator. but that is perhaps european.

[@mrpete222]

+Flip de boer Thanks for watching

[@whitehoose]

Have you considered fitting a small buzzer tapped into the indicator output? many available on e-bay. Could use the simple buzzer and chewing gum approach to adjust volume - or a more sophisticated volume control using a variable resistor so you can set a comfortable level.

[@Mr62Butch]

It looks like the heater coil needs to turn on and off for it to cycle. I'm guessing that when the main contact is closed it by-passed the voltage to the heater effectively shutting it off .

[@dicksargent3582]

+Maurice “Butch” Chauvette Exactly !! So at six minutes Mr.Pete is correct.

[@KM6VV]

I'm thinking that's a bi-metalic curved strip, not just spring steel. Good series!

[@adianetterios5115]

What type of flasher is it or to what car are i need one of those

[@KiwiMaker]

Im amazed at how simple it is! back when you could actually understand how everything worked just by looking at it.

[@Cataskew]

U showed to types of flashers the one with the fine wire starts in the off state when a load larger then the fine heating element is connected it heats the element closing the the switch bypassing the heater sending full power to the light the element cools continuing the cycle. The other type of flasher starts in the on state and relies on the bulb load through the heating element to open the contact and turn off the bulb that flasher reacts more to load and may not flash with a missing bulb or flash very fast with to large of bulbs or a trailer added.

[@mrpete222]

+Cataskew Thanks-thats good info

[@DeArmondTool]

I recall when Dad had to hang his arm out the window to signal!! ;-) For years, he did that even with the turn signal on. Thanks for sharing and bringing back some good memories!!

[@MikeSims70]

Nice video. I've been in and out of electronics since the early 1990's and was unaware of these thermal flashers. Simple concept though certainly, but very energy inefficient compared to digital technology. Well done video!

[@mrpete222]

Thanks

[@JoelHudson]

MrPete222 as stated below, and as I understand it, the "spring steel" part is indeed a a Bi metal strip with a Kink (or bend) in it and when heated it expands deferentially (one side more than the other) and Clicks (AKA Oil canning) and disconnects the heater then after cooling it relaxes, clicks back again and reconnects the heater for another cycle. I hope i've gotten it right :-) thanks for all your "Classes" in Machining etc.