WEBVTT Kind: captions Language: en 00:00:00.080 --> 00:00:01.490 Well, it’s been a minute. 00:00:01.490 --> 00:00:03.598 I’ve been working on a pretty complex topic, 00:00:03.598 --> 00:00:06.540 and in the meantime I need to think of something quick. 00:00:06.540 --> 00:00:09.012 If only I had more time… 00:00:09.012 --> 00:00:10.287 that’s it! 00:00:10.287 --> 00:00:13.271 How ‘bout a little taste of November in January? 00:00:13.271 --> 00:00:17.166 Do you have an electrical thing you want to have turn on at a specific time every day 00:00:17.166 --> 00:00:20.691 and then also turn off at a specific time every day? 00:00:20.691 --> 00:00:22.999 I know, so do I! 00:00:22.999 --> 00:00:25.271 But that sounds really hard. 00:00:25.271 --> 00:00:28.979 I mean, we all know how to make and break electrical connections with a switch - 00:00:28.979 --> 00:00:32.605 you just gotta touch the metal together and then pull it apart real fast! 00:00:32.605 --> 00:00:38.565 And we also have these clock things that have an hour hand that slowly turns in a circle twice a day. 00:00:38.565 --> 00:00:39.844 But y’know… 00:00:39.844 --> 00:00:45.300 some of ‘em only rotate once a day for those that prefer their time served that way. 00:00:45.300 --> 00:00:50.688 I wonder if we could connect the technology of clocks with switches. 00:00:51.460 --> 00:00:53.431 Oh look, it’s a that! 00:00:54.140 --> 00:00:56.652 OK, like a door that’s left its frame, 00:00:56.652 --> 00:00:58.781 that intro was unhinged. 00:00:58.781 --> 00:01:02.757 I’m sure you’ve seen these things before, they’ve been around for a long time. 00:01:02.757 --> 00:01:06.099 In fact, I’m not even sure how long they’ve been around. 00:01:06.099 --> 00:01:09.081 Thanks to that Nintendo thing all the youngin’s are playing with 00:01:09.081 --> 00:01:13.122 internet searches involving the word “switch” are ruined. 00:01:13.122 --> 00:01:19.217 Now, I found a time switch from 1921 which automatically turns stairway lights off after three minutes, 00:01:19.217 --> 00:01:22.019 but that’s not what I want to talk about here. 00:01:22.019 --> 00:01:24.533 I want to talk about ordinary timer switches: 00:01:24.533 --> 00:01:29.128 the kind where you tell it an on and off time and it repeats that daily. 00:01:29.128 --> 00:01:34.430 I suppose this is a sufficiently obvious idea that it got implemented in one way or another 00:01:34.430 --> 00:01:37.146 just as soon as we figured out the light bulb. 00:01:37.146 --> 00:01:41.274 All we really need is a clock that can actuate a switch. 00:01:41.274 --> 00:01:47.579 In theory this could be as simple as a rotary switch which gets hit by the hand of an ordinary wind-up clock. 00:01:47.579 --> 00:01:52.090 When it collides with the switch, it would turn it from off to on and back. 00:01:52.090 --> 00:01:55.567 To make this a little more flexible, instead of giving that clock hands 00:01:55.567 --> 00:01:59.178 we can use a wheel that rotates once per day. 00:01:59.178 --> 00:02:04.875 Then we could attach little actuators to that wheel that will hit the switch, and there you go - 00:02:04.875 --> 00:02:07.042 you’ve just made a timer switch! 00:02:07.042 --> 00:02:10.367 Let’s take a look at this consumer-grade timer switch. 00:02:10.367 --> 00:02:15.649 This Intermatic Time-All was a staple of American life - or at least some American lives - 00:02:15.649 --> 00:02:20.090 in the nineteen seventiesss? Probably? 00:02:20.090 --> 00:02:24.720 I’m having a heckuva time tracking down specific dates for this model’s introduction 00:02:24.720 --> 00:02:31.724 but it’s old enough that it doesn’t have a polarized plug - which makes it borderline useless today. 00:02:31.724 --> 00:02:38.140 But, sure enough, it’s basically a weird-looking 24 hour clock that has a wheel instead of hands, 00:02:38.140 --> 00:02:43.700 and hanging around the edges of that wheel are these little movable tabs marked “ON” and “OFF.” 00:02:43.700 --> 00:02:48.801 You can move them by pushing them down, and then they’ll slide around the edge of the wheel. 00:02:48.801 --> 00:02:53.450 Simply put the ON time where you want it, then the OFF time where you want it. 00:02:53.450 --> 00:02:56.930 Of course, you also need the clock to be set to the right time. 00:02:56.930 --> 00:03:03.569 You set the time by turning the wheel so that the current time lands where the “Time of Day” pointer is pointing. 00:03:03.569 --> 00:03:09.802 Sticking out the side of the device near that spot is a little black knob that’s also marked “ON” and “OFF.” 00:03:09.802 --> 00:03:13.941 That is the actual switch mechanism that the clock activates. 00:03:13.941 --> 00:03:20.452 And when I turn the dial by hand, I encounter resistance once the tabs get near that knob. 00:03:20.452 --> 00:03:23.799 Keep turning and you’ll see that the knob starts to move. 00:03:23.799 --> 00:03:27.016 And right when the tab hits the “Time of Day” indicator 00:03:27.016 --> 00:03:27.930 *click* 00:03:27.930 --> 00:03:31.298 the knob snaps into the OFF position. 00:03:31.298 --> 00:03:36.481 Cleverly, the ON tab can only turn the switch from OFF to ON - 00:03:36.481 --> 00:03:42.389 if the switch is already on, well the ON tab doesn't do anything as it passes the switch. 00:03:42.868 --> 00:03:44.353 Same goes for the OFF tab. 00:03:44.353 --> 00:03:48.213 If the switch is already off, that tab won’t do anything. 00:03:48.213 --> 00:03:52.548 This not only prevents the timer from slipping into the inverse of what you want, 00:03:52.548 --> 00:03:59.990 but it also means that you can manually flip this to ON or OFF to give a temporary override without screwing up the programming. 00:03:59.990 --> 00:04:05.410 The timer will resume normal timed operation when the correct tab hits the switch once more. 00:04:05.410 --> 00:04:07.060 I’ll show you how that works in a moment 00:04:07.060 --> 00:04:12.916 but I want to point out that since this really is just a clock attached to a switch, 00:04:12.916 --> 00:04:15.265 that clock could be powered by anything. 00:04:15.265 --> 00:04:17.655 It could be a wind-up mechanical clock, 00:04:17.655 --> 00:04:19.499 or a battery-operated clock, 00:04:19.499 --> 00:04:25.112 or even gravity driven with chains if you were particularly eccentric. 00:04:25.112 --> 00:04:29.651 But as this thing's gonna get plugged into a wall outlet since... 00:04:29.651 --> 00:04:34.325 that’s its whole thing, the clock mechanism is driven by a synchronous motor. 00:04:34.325 --> 00:04:40.349 That's a special kind of motor that spins in lock-step with the frequency of incoming AC power. 00:04:40.349 --> 00:04:45.999 Since grid operators do a fine job of making sure that power runs at exactly the right frequency, 00:04:45.999 --> 00:04:50.554 and will even make adjustments day-by-day to account accidental for drift, 00:04:50.554 --> 00:04:54.586 it serves as a reliable basis for keeping track of the time. 00:04:54.586 --> 00:04:56.597 At least, usually. 00:04:56.597 --> 00:05:05.725 Since the AC line voltage here runs at 60 Hz, that means the motor will spin at 3600 RPM (assuming it’s a single pole motor). 00:05:05.725 --> 00:05:11.845 That’s, of course, way too fast so a ton of gear reduction is used to slow it down to 00:05:11.845 --> 00:05:17.658 .00069 (nice) RPM or 1 RPD - 00:05:18.409 --> 00:05:20.602 revolutions per day. 00:05:20.602 --> 00:05:25.308 Anyway, here’s where the actual switching and the timing of that comes into play. 00:05:25.308 --> 00:05:29.389 First let’s talk about the electrical switch that makes this thing useful. 00:05:29.389 --> 00:05:32.954 In this timer it’s almost hilariously crude. 00:05:32.954 --> 00:05:38.297 Incoming power from the blades runs right to the terminals of the outgoing receptacle, and - 00:05:38.297 --> 00:05:39.046 woah. 00:05:39.546 --> 00:05:42.638 Hang on, those terminals? 00:05:42.638 --> 00:05:48.086 They’ve got bumps on them which actually engage with the holes in a plug! 00:05:48.086 --> 00:05:50.323 Finally we found something! 00:05:50.323 --> 00:05:52.655 No surprise it’s old. 00:05:52.655 --> 00:05:57.885 Anyway, one blade has a simple wire link attaching it directly to the incoming power, 00:05:57.885 --> 00:06:04.107 and the other runs through two formed pieces of brass that touch through a contact right here. 00:06:04.107 --> 00:06:09.839 The pokey-outey knob of the power switch attaches to a shaft running through the timer body, 00:06:09.839 --> 00:06:17.320 on the other end of which is a simple rectangular bit of plastic which either pushes the contacts apart or lets them the touch. 00:06:17.320 --> 00:06:23.354 A simple 90-degree turn of that shaft is all that’s needed to change switch states. 00:06:23.354 --> 00:06:25.669 As discussed previously on this channel, 00:06:25.669 --> 00:06:31.321 electrical switches should have a snap-action to prevent arcing from damaging the contacts. 00:06:31.321 --> 00:06:37.340 Here that’s accomplished with a simple arrangement of two pieces of metal which act like leaf springs. 00:06:37.340 --> 00:06:40.293 They surround a square cross-section of the switch shaft, 00:06:40.293 --> 00:06:44.520 keeping a slight amount of pressure on it and holding it in-place. 00:06:44.520 --> 00:06:50.919 As the shaft is turned, the corners of the square start to distend the leaf springs by an increasing amount - 00:06:50.919 --> 00:06:54.416 thus increasing the force required to turn the switch. 00:06:54.416 --> 00:07:01.547 But once the square is just past the 45 degree mark into a turn, the springs will now help turn the switch 00:07:01.547 --> 00:07:04.895 and it quickly snaps into the next position. 00:07:04.895 --> 00:07:10.203 This design relies on the timer’s plastic shell to hold the top half of the spring in-place, 00:07:10.203 --> 00:07:17.675 as well as to put pressure right on this spot of the brass link to make the contacts actually touch. 00:07:17.675 --> 00:07:21.053 So then, here’s how the automatic switching happens. 00:07:21.053 --> 00:07:25.580 There’s more going on with those sliding tabs than you can see from above. 00:07:25.580 --> 00:07:27.941 As the dial turns with the passage of time, 00:07:27.941 --> 00:07:31.610 the ON and OFF tabs slowly approach the switch knob. 00:07:31.610 --> 00:07:36.886 The OFF tab has a protrusion that will collide with this wing on the switch shaft - 00:07:36.886 --> 00:07:41.601 time marches on, though, so the tab will slowly rotate the switch. 00:07:41.601 --> 00:07:48.280 And once it’s pushed it far enough, the switch snaps into the next position, opening the switch contact. 00:07:48.280 --> 00:07:53.900 Notice that there are only two wings on the shaft - now that it’s in the OFF position, 00:07:53.900 --> 00:07:59.330 the OFF tab on the timer’s wheel can no longer change the timer’s state. 00:07:59.330 --> 00:08:04.630 The wings are parallel to the wheel and at this point are useless. 00:08:04.630 --> 00:08:09.576 Further into the timer, though, we find another pair of wings on the switch shaft - 00:08:09.576 --> 00:08:13.210 a pair in the opposite orientation as the first. 00:08:13.210 --> 00:08:17.392 The timer’s ON tab has a protrusion just like the OFF tab, 00:08:17.392 --> 00:08:22.967 but it’s positioned inward so it can only collide with this second wing. 00:08:22.967 --> 00:08:26.126 Once it does, of course, it pushes the wing forward, 00:08:26.126 --> 00:08:30.953 turning the shaft, and eventually it clicks over into the ON state. 00:08:30.953 --> 00:08:36.908 This staggered arrangement is how the manual override can work without screwing up the timer settings - 00:08:36.908 --> 00:08:43.120 the ON tab can only ever turn the timer on, and the OFF tab can only ever turn the timer off. 00:08:43.120 --> 00:08:46.897 If it’s already in the same state as the tab would turn it to, 00:08:46.897 --> 00:08:49.372 the tab has nothing to grab hold of. 00:08:49.372 --> 00:08:53.329 This design also allows you to pull the switch knob out slightly, 00:08:53.329 --> 00:08:57.153 which takes those tabs entirely out of alignment with the switch, 00:08:57.153 --> 00:09:02.329 thus turning this into a manually-operated switch until you push the knob back in. 00:09:02.329 --> 00:09:04.370 A nice feature, I suppose. 00:09:04.370 --> 00:09:06.735 While this design works and works well, 00:09:06.735 --> 00:09:08.432 it’s also somewhat limited. 00:09:08.432 --> 00:09:16.240 You can only pick a single on and off time, and the shortest duration you can have between them is two and half hours. 00:09:16.240 --> 00:09:24.830 To alleviate these limitations, eventually Intermatic would change this design from sliding tabs to removable tabs. 00:09:24.830 --> 00:09:27.710 This timer here is one such example. 00:09:27.710 --> 00:09:31.970 The overall method of operation is remarkably similar to the first timer. 00:09:31.970 --> 00:09:35.025 We have a rotary switch, though now it’s up here, 00:09:35.025 --> 00:09:40.970 and the on and off tabs simply push that switch into the next position when they collide with it. 00:09:40.970 --> 00:09:45.030 The green tab turns it on, and the red tab turns it off. 00:09:45.030 --> 00:09:50.339 The two tabs have their switch actuator pokey bits at different depths so, just as before, 00:09:50.339 --> 00:09:54.180 the on tab can only turn it on and vice versa. 00:09:54.180 --> 00:09:56.413 The similarities don’t stop there, though. 00:09:56.413 --> 00:10:01.222 Internally we have a remarkably similar motor and gear reduction drive, 00:10:01.222 --> 00:10:04.804 and the switch itself is still quite crude. 00:10:04.804 --> 00:10:06.795 It’s also damaged on this one because 00:10:06.795 --> 00:10:10.886 SOMEBODY decided they should hide a screw underneath the clock dial 00:10:10.886 --> 00:10:15.490 and I didn’t figure that out until AFTER I went ham with a screwdriver and pliers. 00:10:15.490 --> 00:10:18.748 Anyway, this time they’ve refined the switch 00:10:18.748 --> 00:10:24.399 by making the switch blades double as the springs which provide that nice snap-action. 00:10:24.399 --> 00:10:27.130 But otherwise it’s still just as crude - 00:10:27.130 --> 00:10:30.681 are these wires even soldered to the motor leads? 00:10:30.681 --> 00:10:35.048 Oh but this time they did at least take care to switch the hot leg. 00:10:35.048 --> 00:10:41.545 In the old timer, if you installed it upright on the most-common outlet orientation you’ll find here, 00:10:41.545 --> 00:10:43.403 the switch broke the neutral. 00:10:43.403 --> 00:10:45.179 Very good. 00:10:45.179 --> 00:10:47.702 I mean it wasn’t polarized anyway but still. 00:10:48.000 --> 00:10:55.030 Anyway, since you actually remove and replace these tabs on this design to set the on and off times, 00:10:55.030 --> 00:10:58.740 you can add more if you want a more complex program. 00:10:58.740 --> 00:11:03.273 When new these timers came with two or maybe three pairs of tabs, 00:11:03.273 --> 00:11:12.990 but tabs are very easy to lose and unfortunately Intermatic didn’t think of designing some sort of tab-holder into this to store them. 00:11:12.990 --> 00:11:17.682 You’d think this might be for that purpose but nope, they don’t fit there, 00:11:17.682 --> 00:11:21.980 so those extra tabs tended to disappear. 00:11:21.980 --> 00:11:24.692 Don’t worry, they sell replacements! 00:11:24.692 --> 00:11:27.764 Actually as a matter of fact you can still buy this timer new, 00:11:27.764 --> 00:11:30.286 though stock appears to be dwindling. 00:11:30.286 --> 00:11:35.404 Also, you can indeed put the tabs right next to each other and the timer will work - 00:11:35.404 --> 00:11:40.896 so if you want something to be on for just a half-hour, well now you can do just that! 00:11:40.896 --> 00:11:43.637 Luckily, at some point somebody asked 00:11:43.637 --> 00:11:48.243 “why are we faffing with those tabs?” and designed a timer like this one. 00:11:48.243 --> 00:11:55.538 Now, the face of the timer has 48 individuals tabs along its perimeter which can be up or down. 00:11:55.538 --> 00:12:03.726 Annoyingly these things almost never bother with printing “up is off, down is on” so it’s always a game of trial and error setting one up, 00:12:03.726 --> 00:12:08.764 but once you figure it out you’ve got all the flexibility this design could ever offer, 00:12:08.764 --> 00:12:14.520 and without the risk of losing the tabs since they’re now permanently attached to the timer. 00:12:14.520 --> 00:12:22.253 Internally, we still have a synchronous motor and gear reduction making the dial rotate once per day by way of this drive gear, 00:12:22.253 --> 00:12:27.959 but now we have an off-the-shelf microswitch doing the switching with micro flair. 00:12:27.959 --> 00:12:32.412 A simple lever connects the switch’s actuator to the perimeter of the dial. 00:12:32.412 --> 00:12:39.430 In this design, the dial acts as a very slowly turning cam which that lever rides against. 00:12:39.430 --> 00:12:41.309 When the tabs are in the down position, 00:12:41.309 --> 00:12:46.430 they push on that lever which depresses the switch actuator allowing power to flow. 00:12:46.430 --> 00:12:52.079 However, when they’re in the up position they leave space for the lever to fall into, 00:12:52.079 --> 00:12:55.501 and that releases the switch, opening the contact. 00:12:55.501 --> 00:13:00.798 Microswitches have their own internal spring mechanism to make the switch action happen quickly; 00:13:00.798 --> 00:13:03.458 you can hear it clicking when I depress it manually. 00:13:03.458 --> 00:13:05.209 *clicky clicky clicky click* 00:13:05.209 --> 00:13:08.273 And since it always wants to push that actuator out, 00:13:08.273 --> 00:13:15.239 the switch will in effect turn itself off as soon as the lever falls into the cam thanks to a pulled-up tab. 00:13:15.239 --> 00:13:20.352 This design also allows for a simple slider to provide a program override - 00:13:20.352 --> 00:13:25.698 slide this over and now the switch is pressed in regardless of the tab situation. 00:13:25.698 --> 00:13:30.137 However, it won’t automatically resume the program like the Intermatic timers will. 00:13:30.137 --> 00:13:34.848 It will only return to the program when you switch it back to timed operation. 00:13:34.848 --> 00:13:38.371 Now, in case you haven't realized, it's 2023. 00:13:38.371 --> 00:13:43.746 These days we have more phosticated ways of timing when things can and cannot get power. 00:13:43.746 --> 00:13:47.966 But mechanical timers like these still have their applications. 00:13:47.966 --> 00:13:52.068 I whip out a few during Christmas time for some indoor lighting displays. 00:13:52.068 --> 00:13:59.780 And it can be nice to set up, say, a floor lamp on a timer like this to give you some light when you get back from a day out and about. 00:13:59.780 --> 00:14:02.866 It may be basic, but it’s still automation. 00:14:02.866 --> 00:14:09.693 And in the commercial realm, you still see similar timers used for things like defrost cycles in refrigeration equipment, 00:14:09.693 --> 00:14:13.050 lighting signage so it goes out after closing time, 00:14:13.050 --> 00:14:16.220 or even just exterior lighting in general. 00:14:16.220 --> 00:14:21.691 Though photocells are usually a better option since the sun does that thing where the days get longer and shorter. 00:14:21.691 --> 00:14:24.420 But as electronicals get cheaper and cheaper, 00:14:24.420 --> 00:14:30.930 well now it’s just as likely that when you need a basic timer you’ll be getting something like this. 00:14:30.930 --> 00:14:34.947 A microcontroller hooked up to a display, some buttons, and a relay 00:14:34.947 --> 00:14:37.503 makes for a very flexible timer. 00:14:37.503 --> 00:14:40.440 Want different programs for weekdays and weekends? 00:14:40.440 --> 00:14:42.019 Knock yourself out. 00:14:42.019 --> 00:14:44.410 Concerned about the time drifting with a power outage? 00:14:44.410 --> 00:14:50.040 Well, just stick a little rechargeable cell on the board and use a clock crystal as your time base. 00:14:50.040 --> 00:14:55.144 You can even get inexpensive timers which, after telling them where you are on the planet and the date, 00:14:55.144 --> 00:14:58.793 will automatically adjust sunrise and sunset times throughout the year 00:14:58.793 --> 00:15:02.135 all without needing WiFi or an app. 00:15:02.135 --> 00:15:03.762 And that’s pretty neat. 00:15:03.762 --> 00:15:09.864 Still though, I can’t help but admire the charm that is a clock which turns a switch. 00:15:09.864 --> 00:15:12.878 Or, I guess, presses a button in some cases. 00:15:12.878 --> 00:15:15.926 Take two basic things, smoosh them together, 00:15:15.926 --> 00:15:19.004 and you can make a pretty handy new third thing! 00:15:19.004 --> 00:15:23.020 Do it well enough, and you can even change the world. 00:15:23.020 --> 00:15:26.843 Thanks to Mike for sending these timers my way way back when when, 00:15:26.843 --> 00:15:29.656 and of course thanks for watching. 00:15:30.573 --> 00:15:33.129 ♫ regularly-scheduled smooth jazz ♫ 00:15:33.504 --> 00:15:36.772 I’ve been working on a pretty complex tompic…. Tompic? 00:15:36.772 --> 00:15:38.050 Awwwghh 00:15:38.488 --> 00:15:39.486 That’s it! 00:15:39.486 --> 00:15:41.906 How ‘bout a taste of little November [laughs] 00:15:41.906 --> 00:15:45.126 I mean, we all know how to make and break electrictcalkiconnec 00:15:46.210 --> 00:15:49.805 I suppose this is a sufficiently obvious idea that it got incorp -- 00:15:51.911 --> 00:15:53.329 Dahh, I could’ve made that work. 00:15:53.329 --> 00:15:56.569 I suppose this is a sufficiently obvious idea that… 00:15:56.569 --> 00:15:58.829 it got implemented in one way or another… 00:15:58.829 --> 00:16:00.564 just as soon as we figured out the light bulb. 00:16:00.564 --> 00:16:02.699 Why is the pacing so wrong? 00:16:02.699 --> 00:16:03.668 *click* 00:16:03.668 --> 00:16:06.160 the knob snaps into the off position. 00:16:07.411 --> 00:16:09.039 Except I just turned it on. 00:16:09.039 --> 00:16:14.640 One blade has a simple wire link attaching it from the from the from the from thing. 00:16:14.640 --> 00:16:16.238 Internally we… 00:16:17.114 --> 00:16:18.585 good god! 00:16:19.919 --> 00:16:22.926 So, it was just about time for this video, eh? 00:16:22.926 --> 00:16:26.766 Do you think when doing inventory, after discovering a lack of certain herbs, a chef will yell 00:16:26.766 --> 00:16:28.972 "we're running out of thyme!"? 00:16:28.972 --> 00:16:34.194 I mean, if I worked as a chef, you can bet your bottom dollar that I would. 00:16:34.965 --> 00:16:36.215 Every thyme.