Curvature of the Earth

We all know that the surface of the Earth is curved, but exactly how ‘curvy’ is it?  At what scale do you actually need to start compensating for it in a construction project?  Let’s do some easy math and find out…

The Earth is not a sphere — it’s actually an oblate spheroid — but since oblate spheroid math requires a university degree to understand, we can simplify things by treating the Earth as a sphere.  That makes the calculations understandable by anyone who has passed, say, Grade 10 or 11 high school math.

The mean radius, r, of this simplified Earth sphere is 6,371,008m.

Let d be a straight-line distance that you project at a tangent from any point on the Earth’s surface:

Application of Pythagoras’ Theorem gives the following:

c² = a² + b²
(r+h)² = r² + d²
r+h = √(r² + d²)
h = √(r² + d²) – r

…where h is the height of the end point of that line above the surface of the Earth.

A distance of 1,000m is something that most people can relate to, and is probably near the upper limit of what you would use for large-scale projects, so I’ll use that distance to calculate the magnitude of curvature of the Earth.

Solving with d = 1,000m we get:

h = √(6371008² + 1000²) – 6371008
h = 6371008.078480516 – 6371008
h = 0.078480516m
h ≈ 78mm

So, to put this in a way that I hope everyone can understand:

The surface of the Earth is not now, nor has it ever been, flat —
it falls away from a perfectly straight line at the rate of 78mm every 1,000m.

Thanks to similar triangles and the metric system, you can interpolate easily from that number:

78mm @ 1,000m  ≡  7.8mm @ 100m  ≡  0.78mm @ 10m  ≡  0.078mm @ 1m

So, if you built a house that was 10m long on top of a perfectly flat concrete raft, and placed it on the surface of a perfectly spherical Earth, the curvature of the Earth would result in a 0.78mm gap under one edge of the raft.  It would take 8 sheets of 75gsm photocopy paper or 1 grain of coarse sand to fill that gap.

If a 0.78mm fall over 10m (or any of its equivalents) does not compromise the integrity of your construction, then you can safely ignore the curvature of the Earth — pretend that the Earth is flat* — and just build it.  No-one will suffer.

Now you know.   Happy building.  🙂

* Treating the Earth as flat for small-scale construction projects is perfectly fine.  However, believing that the Earth is flat means you’re joining the ranks of a bizarre religious cult — and that’s not a good idea.  The curvature of the Earth is hard to see with the human eye, and hard to measure with the sort of measuring devices ordinary folks can buy at a hardware store.  Just because it looks flat doesn’t mean it is.  The challenge folks have in measuring that curvature at small scales is due simply to a) the lack of precision and accuracy of their instruments, and/or b) their lack of mathematical skill.

To be fair, very few of us construct things on a scale where we need to factor in curvature of the Earth, so we can happily go through life ignoring its existence.  That doesn’t mean curvature doesn’t exist — it just means ordinary folk don’t need to calculate it, compensate for it, or even worry about it, in their day-to-day lives.  Rest assured, however, that every modern engineer that signs off on a bridge, stadium, dam, airport runway or terminal, canal, supertanker, cruise liner, cargo ship, hospital, aircraft carrier, freeway intersection, railway station, shopping mall, or tunnel has obtained super-accurate measurements and crunched the numbers to compensate for curvature of the Earth — to ensure that their constructions don’t fail and that people don’t die.

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Free Dehumidifier

Air too humid inside your house?  Got mould problems?  Clothes take ages to dry inside during the wet season?  How does a free dehumidifier with zero running costs sound?

Most folks don’t know that their ‘frost free fridge’ can easily be hacked to act as a dehumidifier.  As it runs continuously, it can be used to suck moisture out of a humid house all.. year.. long.

Frost free fridges actually have a heating element.  This heating element comes on every-so-often to thaw out the cooling plate.  Any frost/ice that has formed on the cooling plate melts, drips into a plastic trough, drains to the bottom-rear of your fridge via a small tube, and then ends up in a plastic bowl located on top of your compressor.  The compressor, as it works to pump heat out of your fridge and into the surrounding air, heats up.  Heat from the compressor warms the bowl and evaporates the water, returning the moisture back to the air where it originally came from.  So, under normal circumstances, this operation is humidity-neutral.

Assuming that your fridge is against an external wall, or above an accessible basement, or near a drain, you can get a short piece of scrap tubing, attach it onto the end of the drain tube (just above the bowl), and instead of the water ending up in the bowl, it can be redirected outside, into a container or into a drain.  In any case, since it is no longer being heated and evaporated back into the air, it is effectively removed from the humidity equation and your internal air becomes drier.

Depending on how easy it is to access the back of your fridge, this hack takes mere minutes.  I think it took me all of 5 minutes to do mine — and I chose to drill a hole into our back wall so that the water would go to plants outside.

It doesn’t take any extra electricity, and doesn’t harm your fridge in any way.  It’s just the free 24/7/365 dehumidifier that you all have in your kitchen but weren’t aware of.

Enjoy!

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Slow ADSL Download Speeds

Got an ADSL connection that’s running slow?  Downloads taking too long?  Wonder if there’s anything you can do to speed things up?  Maybe, maybe not.

80605762

Note:  The bulk of this post was originally in response to a question from someone who was getting only 1Mbps download speeds on their ADSL connection.  Since the issues are the same regardless of how slow your connection is, I figured I’d post it here and expand on it if folks are interested.  Whilst some of the content is specific to Australia, most of it is generic and applies to ADSL connections anywhere.

Real world ADSL speeds are primarily limited by the distance to the exchange and then by line noise.

Before you do anything else, make sure that you actually have a problem by checking units.  Mbps is not the same as MBps.  1MBps is fine, but 1Mbps is very low for ADSL.  There are 8 (b)its in a (B)yte, so 1MBps is actually 8Mbps.  Lots of applications report transfer speeds in MBps and they aren’t always consistent (or correct) in their capitalisation.  Use something like speedtest.net to verify your download speed in Mbps.

Assuming that you do indeed have a download rate of 1Mbps, then the next thing you need to check are the laws of physics.  Signals lose strength as they travel down copper wires, and since download speeds are linked to signal strength that means the further away from the telephone exchange you are, the slower your download rate will be.  Use something like adsl2exchanges.com.au to find out what your estimated maximum speed should be.  If you’re within 40% of this number then you don’t have a significant problem (cable runs are often much longer than straight-line distances).

If you can’t get an estimated maximum speed from the above website, or another similar website, but you can get a distance to the exchange, then use the distance with the following chart (from Internode) to estimate your maximum speed yourself:

internode-adsl2-dist07

If what you get from speedtest.net is less than 60% of the maximum rate that you could get according to adsl2exchanges.com.au then there’s likely to be a problem somewhere.  How significant a problem depends on how big the difference is.

Line noise is the next biggest limiting factor.  Bean-counters at Telecom/Telstra have forced technicians to use cheaper, sub-optimal compounds to moisture-proof connections for over two decades with the consequence being that, when it rains heavily, junction boxes and pits flood, water often penetrates the connections, and low-level short-circuiting occurs.  You can tell if this affects you because when you go to make a phone call (using your analogue land line) just after a decent rain, you’ll hear lots of static, crackling and pops on the line — line noise.

Since your ADSL rides on top of the underlying carrier signal, whenever that signal gets disrupted, you lose packets and your Internet application needs to re-send those packets.  This is known as ‘packet loss’.  Having to re-send lost packets takes time and slows down your transfer speeds.  If you have a decent router, you could log into the router’s web interface and bring up a chart or some statistics showing you how much packet loss your line is experiencing.  If packet loss increases after local rains, but is negligible during dry periods, then that’s your problem.

The real problem, however, is getting it fixed.  If you detect line noise and report it to your ISP then they’ll open a ticket with Telstra who will take, at least, two days to get back to you.  By that time the rains have stopped, the junction boxes have emptied, the connections have dried out, and the signal noise is gone.  So when the technician rocks up and test your line, the device they use reports that the line is working fine.  /sigh

The final source of line noise is within your house.  This is a vast topic in and of itself, but basically the more phone sockets, connections, splitters, adapters, extension lines, analogue phones, security systems, and so-on that you have connected to your line, the more line noise there will be.  As an experiment, you could disconnect absolutely everything from your phone system, then connect only your router to the master/main phone socket (the one closest to where the line comes in from outside) and do a speed test with that.  If there’s a big improvement in speed then one of the things you disconnected must have been causing substantial amounts of noise.  Shouldn’t be too hard to work out which one if that’s the case.

Optimising an Internet connection is not a trivial process.  You need to be prepared to research all of the relevant issues and absorb and understand technical information.  There is no magic green ‘go fast‘ button that you can press.  Sometimes 1Mbps is as good as it gets!  The location of your house, the location of the exchange, the condition of the line between them, the laws of physics — none of these care about whether or not you are happy with the speed of your Internet connection, and you usually can’t change (‘fix’) any of them.

The best you can do is simplify the wiring within your home, and maybe try a different router (to address chipset incompatibilities).  If that doesn’t fix the problem, then the problem probably can’t be fixed.  You then have no option but to use a different technology to connect to the Internet (cable, fixed wireless, HFC, mobile, fibre…).

Finally, this problem isn’t going to get better in Australia — it’s only going to get worse.  The government is basically abandoning the copper network (and everything that relies on it).  This is clearly evident in how the NBN operates.  If you get a new NBN connection, they will decommission your land line within 18 months — literally cut it off.  The writing is on the wall for the copper network.  That’s why no-one is really interested in fixing house-to-exchange line noise issues — crumbling infrastructure and slow speeds are a good way to ‘encourage’ users to stop using the copper network and switch to the NBN.  You can voluntarily walk the plank, or wait until you are pushed — either way you are leaving the ship.

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Lawn Tractor Oil Filter Tips

If you have a John Deere D125 lawn tractor (aka ride-on mower), or pretty much any of the D-series, and have ever replaced the oil filter, then you’ll know how annoying it can be.  The crux of the problem is that:

  • the ‘proper’ oil filter (the AM125424 for a D125) is a very short filter
  • the oil filter is positioned so that there is very little clearance between the filter and the frame

This causes a couple of issues:

  • there is not enough clearance to use many oil filter removal tools
  • there is insufficient room to hand-tighten the new oil filter

The solution is rather simple:  Install a longer oil filter!

Providing that a longer oil filter will not come into contact with the closed hood, or any other moving part, you can simply buy a (slightly) longer one and install that instead.  The fluted end of the oil filter will then project beyond the frame which will make (un-)installing it a whole lot easier.  The larger filters sometimes even cost less, because they are used on more machines and produced/stocked in larger quantities.

(Of course this design issue/fault affects many other lawn tractors, not just the JD D-series.)

The second tip is pretty common knowledge, but worth repeating anyway:  After you’ve smeared a small amount of fresh oil over the rubber gasket on the new filter, and wiped clean the part of the engine block that the gasket will mate with, screw on the new oil filter and then hand-tighten it firmly in place.

There is absolutely no need whatsoever to use a tool to install an oil filter, and risk damaging it.  Even the tiniest hole or crack will ultimately lead to oil loss and very bad things happening to the engine.  If the new filter is clean and your hands are relatively oil free, you should be able to get a good grip with both hands and torque the filter enough to ensure a solid seal.  You don’t need to go ape on the thing.

Finally, with your new filter installed you’ll fill up with fresh oil.  Once you’ve got the oil level between the two notches on the dip-stick, run the engine for about thirty seconds.  Any trapped air should get purged from the system.  Check the oil level again and you’ll see it has dropped a little.  Top up (if required) to bring it back up to the desired level.

If you don’t take the time to perform this extra step, you may end up running the engine with inadequate oil which will result in increased engine wear and premature failure of certain components.

Oil filters may not be sexy, but they are very important and filter changes are worth taking the time to do right.

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The Future of the Electrical Grid

Grid power is dirty!  It’s polluting the planet!  We should all put solar panels on our roofs, some batteries in the shed, and go off-grid!  For the sake of the children!  Hmmm… Not so fast.

This post is about the electrical grid (“the grid”), why it’s not going to go away, and why (eventually) it will be ‘green‘.  Hard to believe?  Read on.

electricity-grid-australia

The electrical grid in most developed nations is a reliable way to connect the consumers of electricity to the producers of electricity.  Electricity is generated in various places, by various means (e.g. coal, natural gas, nuclear, hydro), fed into the grid, distributed around the country, and ultimately reaches your house where you flick a switch and power some sort of device.  Fantastic!

One not-so-fantastic aspect is that most of the energy comes from non-renewable, polluting and/or dangerous sources like coal, natural gas and nuclear.

Another not-so-fantastic aspect is that after a month or three a bill arrives to account for your usage.  You must pay that bill in order to remain connected to the grid and enjoy its benefits.  Every bill seems to get larger and larger.  Ever-increasing electrical bills are financially hurting a huge number of people and have pushed many to install solar photovoltaic (PV) panels on their roofs.

Solar PV panels generate electrical power when the sun shines.  The house uses as much of this power as it needs and any surplus is exported to the grid.  When it’s cloudy or dark or your consumption rate is high, the panels don’t generate enough power to meet household needs, so the deficit is imported from the grid.

Yes, this is how ‘net-metering’ works, and things work a bit different for those on ‘gross-metering’ plans, but I’m keeping things simple for now and so will focus on how it works for most folks.

Most folks, naturally, want to minimise their electricity bill as much as possible.  A decade ago PV panels were so expensive that installing enough of them to generate all the power that a house needed was rare — PV arrays tended to be small.  The demand for panels worldwide, however, has pushed the prices down so much in the last decade that they are now quite cheap.  It is now common for folks to install large arrays that generate more power each year than their house actually uses.  That creates a problem.

In order to reduce emissions and “combat climate change” most governments encouraged people to install PV arrays by mandating that electricity suppliers pay customers for the power that their arrays feed back into the grid.  When arrays were small, this wasn’t a problem because all it would do is reduce the size of a bill by a bit.  Now that arrays are large, bills are often zero or even negative (your supplier has to pay you).

Whilst paying customers is great from the customer’s point of view, it is really, really bad from the supplier’s point-of-view.  It costs money to maintain the grid.  As more and more customers install bigger and bigger arrays, and payouts to those customers keep increasing, there is less money left over to maintain the grid.  This results in reduced investment and maintenance (resulting in more brownouts and blackouts) and increased fixed and variable costs in everyone’s bills.  In a very real sense, if you install solar panels on your roof, and receive any money at all for the power you export, you are directly responsible for increasing the size of power bills for everyone.  It’s sad, but true.

One other problem introduced by people installing PV arrays, and feeding surplus power back into the grid, is the mismatch between demand and supply.  If you leave your house to go to work during the day, the amount of power being used by your house is very low, so most of the power generated by your array ends up being surplus and gets exported to the grid.  At night, you come home, prepare dinner, turn on all the lights, the TVs, the AC and your consumption spikes — at the same that time it’s (getting) dark outside and your array is generating very little (if anything at all), forcing you to import the deficit from the grid.

Now expand this to everyone in your time zone.  The sun rises at the same time for all of you, so all of your rooftop arrays are generating surplus power when you are at work and don’t need it, and not generating much at all when you are at home and do need it.  Let’s not even get started on large-scale weather systems moving across regions causing massive fluctuations in PV generation on a minute-by-minute basis.

These things play havoc with the grid and, ultimately, make the grid less efficient, more expensive, and less reliable.  In a nutshell, solar PV arrays are the worst (most disrupting) thing to ever happen to the grid.  Who in their right mind wants to stay connected to a grid that delivers dirty power, keeps getting more expensive, and keeps getting less reliable?  The answer is obvious.

“Grid defections” is a term used by power companies to describe the customers that were once connected (tied) to the grid, but chose to install solar panels, their own electrical storage system (batteries), and then disconnect from the grid completely. Grid defections are on the rise.  Areas with high power prices tend to experience the largest rate of grid defection.

Grid defection is making the problem worse for suppliers.  An electricity bill has a fixed component (often called something like a “connection fee”) which you have to pay regardless of how much power you use.  The other part of the bill is the variable component — this is the amount you pay for the power you actually use.  Unless you have some way of storing the power your array generates (so you can use it at night, for example) then you can’t defect from the grid.  Batteries let you do this, but they have, historically, been quite expensive.  Most folks that are grid-tied don’t have batteries at all — the grid acts as their battery.  Now that companies (like Tesla) are making more and more batteries, it is becoming cheaper and cheaper to add batteries to your PV system.  If you have a big enough array, and a big enough battery bank, it makes little sense to remain connected to the grid and keep paying that fixed component on your bill.  Grid defection becomes the ‘financially logical’ choice.

Folks that defect from the grid no longer contribute anything towards its maintenance costs.  Since the maintenance costs are still the same, but there are fewer people left behind to pick up the tab, all of their bills go up.

The future sounds pretty bleak for the grid, right?  It’s just a matter of time before it collapses under its own weight and dies, right?  The enemies of the evil, dirty grid are probably cheering at the thought.

But here’s the thing…

Electricity suppliers are at a critical fork in the road:  “Business as usual” will result in bankruptcy (because large grid-tied PV arrays and grid defections will ultimately kill their business model).  Adapting to the new reality is their only real choice.  That means coming to terms with, and dealing with lots of solar PV customers and the unavoidable supply/demand mismatch.

Some (perhaps even many) suppliers will cling onto the past, will fail to adapt fast enough, and will go out of business. The remaining suppliers will cannibalise the corpses of those that fall, take their remaining assets and customers, and forge ahead.  Key to survival is solving the supply/demand mismatch (aka ‘load balancing’).

geesthacht_1Power companies are already developing ways to store surplus solar PV power until they need it.  Traditional (utility-scale) chemical batteries (like the ones Tesla have in mind) are one way to do this, and pumping water uphill into a big dam when the sun shines and releasing it when the sun doesn’t (pumped hydro) is another.  Whilst pumped hydro is the current leader (with over 168GW of installed capacity worldwide) geographic limitations mean that it can’t be used everywhere, so different solutions will be employed by different power companies in different regions.  As a research field, it’s exploding.

Viable solutions to the load balancing problem already exist and have been implemented.  New solutions are being developed and tested right now.  The problem has already been partially solved.

But here’s the kicker…

All of the leading contenders for grid energy storage are environmentally friendly (or, at least, more environmentally friendly than coal, natural gas, or nuclear).  Pumped hydro, for example, is basically just a dam with a turbine generator and a pump.  Power is generated when water flows out, then surplus solar PV power is used to pump water back.

As more and more PV arrays get installed, more and more surplus power will be available on the grid to ‘do something useful’ during low-demand periods.  The price of this surplus power will be very low.  Such conditions allow grid energy storage systems to be economically viable.

On a personal level, the more PV panels you install, and the more power you feed back into the grid, the more surplus power will exist, the more opportunities will be created, the faster your region will end up with an environmentally friendly grid energy storage system, and the ‘cleaner’ the electricity that everyone pulls from the grid will be.

Grid energy storage systems are allowing solar to take over from coal, natural gas and nuclear in providing environmentally friendly base loads for the entire grid.

So, defecting from the grid is something you can do right now to help your wallet and the environment right now.  It won’t help anyone else though.  Staying connected to the grid, installing as many solar panels as possible, and exporting as much power as possible, may not help your wallet quite as much — but you will hasten the rate at which clean grid electricity becomes available, for everyone.

May your days be sunny ones.

PS:  The purpose of this post was not to advocate any one approach.  It was to frame the discussion from a different angle and encourage folks to think about it a bit deeper.  It’s good to challenge assumptions once in a while.  The world keeps changing around us and sometimes those old assumptions are no longer valid.  Unless you re-evaluate the situation every-so-often you may end up walking a long way down a path that is no longer the right one for you.

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Disabling Lawn Tractor Safety Switches

Like many others, the 2015 John Deere D125 Lawn Tractor (aka ride-on mower or garden tractor) has two annoying safety switches.  One stalls the engine if you mow in reverse without pressing a button.  The other stalls the engine as soon as you get off the seat (or lean too much forward or to one side).  This post is about disabling/bypassing the (newer) seat safety switches.

John Deere D125 seat switchUnlike older models, the new seat safety switch now has four pins, and not just two wires, so things are a little bit more complicated than the ‘cut and short’ solution presented on many older YouTube videos.  ‘Cut and short’ will not work on the newer safety switches.

I conducted some research and found out that the switch itself is JD Part Number GY20073.  It is available for next to nothing to people in the US, but the price increases by a factor of about 500% when you try to get it in Australia.  Further research reveals that the (alternately-branded) Rotary 14246 Plunger Safety Switch is identical and much cheaper to source in Oz.

Having thus acquired a seat safety switch, I then used a multimeter to test the electrical continuity between all possible combinations of pins.  This was first done with the switch in its default ‘off’ position (spring-loaded pin all the way up) and then in its ‘on’ position (pin pressed down).  Here are the results:

  • switch ‘off’ (pin up)
    • open circuit:  1-2, 1-3, 2-4, 3-4
    • closed circuit:  1-4, 2-3
  • switch ‘on’ (pin down)
    • open circuit: 1-2, 1-3, 1-4, 2-3, 2-4, 3-4
    • closed circuit: nothing

What this tells us is that when no-one is sitting on the seat, the outer pair of pins are connected and so are the inner pair of pins, but when a person sits on the seat all of the pins are disconnected.  This is surprising, as what it means is that to simulate a person sitting on the seat (the pin being pressed down) all you need to do is make sure none of the wires are connected — and that would be as easy as just unplugging the connector from the safety switch!

This was such a surprise that I actually didn’t believe it.  It doesn’t make sense to build a ‘safety’ switch that can just be unplugged by an end user.

Closer examination of the switch with a magnifying glass revealed some imprinting:  63DH, DELTA SYSTEMS INC, STREETSBORO OHIO, US PAT NO 6,207,910.  Examining the patent online made for a couple of hours of painstakingly slow but interesting reading.

The patent for this switch describes it as a “low profile, two pole, plunger-type safety switch”.  The electrical testing confirms two pole behaviour.  What was really interesting, however, is that the patent also includes the design of the connector — and the interaction between the two is where some clever engineering magic happens.

As “it is desirable to prevent an operator from bypassing the operation of the safety functions provided by a seat mounted safety switch by simply disengaging the connector coupled to the switch housing” the engineers designed the connector to short-circuit the two middle wires in the connector itself when it was unplugged.  Sneaky devils!

US06207910-20010327-D00006As can best be seen in FIG. 12, when the connector housing 202 is engaged with the switch housing 112, the beveled edges of the triangular nubs 127 a, 127 b extending outwardly from the forward edge of the bottom cover 117 contact and deflect downwardly the arcuate portions 264 of the forwardly extending arms 262 thereby permitting electrically connection or nonconnection between the socket assemblies 210 b, 210 c to be determined by the position of the actuator 130

So, what seems to be happening is that the two middle wires (2 and 3) are being used to make sure that the connector is actually connected to the switch and also sense the position of the pin.  If 2-3 is closed circuit then either a) the connector has been unplugged, or b) the connector is plugged in but there is no-one on the seat (pin is up).  In either of these cases the motor won’t run.  If 2-3 is open then a) the connector must be plugged in and b) there should be someone on the seat (pin is down).

The outer two wires (1 and 4) only sense the position of the pin.  If 1-4 is closed-circuit then there is no-one on the seat (pin is up).  If 1-4 is open circuit then someone’s on the seat (pin is down).

It is thus almost certain that both 1-4 and 2-3 need to be open-circuit in order for the motor to run.

The utterly trivial conclusion to all of this is that, in order to bypass the seat safety switch in your lawn tractor all you need to do is cut the cable before the connector.  Simply cutting the cable and then insulating the exposed ends will ensure that no circuits are ever closed and therefore that all of them remain open — thus mimicking the electrical behaviour of the connector being plugged into the switch and the pin being pressed down.

Wow, just wow.

So, having done my homework and testing, it was now time to put the theory into practice.  I had a few hours of mowing to do and a bit of spare time up my sleeve, so I pushed the lawn tractor out of the shed, tilted the seat forward and unceremoniously cut the wire all the way through with some snips.  Brought the seat back down, hopped on the seat, applied the brake, pushed the throttle up to the choke position and turned the ignition key — the starter turned a few times and then the engine roared to life.  I let the engine warm up for a while and then, with the motor idling, just hopped off the seat… and… nothing changed!  The engine kept on running.  Success!

I then happily mowed for a few hours, hopping off frequently to open gates, move obstacles and pick up pieces of rubbish — and the engine kept running regardless of whether or not the mower deck was engaged or what revs it was pulling.

Brilliant, just brilliant.  Makes mowing so much more efficient and enjoyable!  🙂

Side note:  On the JD D125 the seat safety switch wire that you cut is enclosed in a springy plastic sheath that runs down into a hole in the chassis of the tractor.  When you tilt the seat forward this stretches and is thus under tension.  When you cut through the wire the bottom part will probably withdraw down through the hole and quickly disappear from view.  Don’t bother trying to fish through the hole with your fingers, pliers, or a wire.  Kneel down next to the right, rear wheel and look just above and forward of the wheel — you will see the wire/sheath clamped to the frame.  The part protruding up from the clamp will be the loose end you just cut.  Use cable ties to secure this loose end somewhere so it won’t rub against anything metal or collect water.  If you are particularly paranoid, or often drive your tractor through puddles, consider even taping or plugging the end with something to seal it.

Remember that the wires in this loose end need to always remain open-circuit.  If they are rubbing against metal parts or bridged with a droplet of muddy water, then they can close-circuit and — as far as the electronics of the engine are concerned — signal that the operator has left the seat and result in the engine stalling (or not starting).  If the contact is intermittent (as it would be if vibrations were bouncing the wires against a metal part) then they could send conflicting signals multiple times per second to the engine which would result in erratic engine operation (symptoms similar to an engine being starved of fuel).  Secure and/or seal the loose end to eliminate this problem from developing down the road.

According to greenpartstore.com the switch is used in (and thus this bypass will work for) all the following models:

  • 102, 105, 115, 125, 135, 145
  • D100, D105, D110, D120, D130, D140, D150
  • L100, L105, L107, L108, L110, L111, L118, L120, L130
  • LA100, LA105, LA110, LA115, LA120, LA125, LA130, LA135, LA145, LA155
  • LT150 after serial number 040,259
  • LT160 after serial numbers MOL160H035097, MO160C035447, MO160D415192
  • LT170 after serial number 035,001
  • LT180,  LT190
  • LTR180 after serial number 500,001
  • G110
  • X110, X125, X130R, X145, X155R

It is likely that many other brands of lawn tractors or garden tractors (e.g. Husqvarna, Sabre, Scotts) use a similar, if not identical switch and can be bypassed in the same way.

Disclaimer

I am neither young nor stupid.  I’m never in a rush when I mow.  I pay attention to where my feet are.  My property is flat and the soil is sandy.  The D125 comes to an automatic halt if you take your foot off the pedal.  In my particular situation the negatives of a seat safety switch far outweigh the positives.  Your circumstances are probably different.  Use your brain.  Safety switches exist to protect you in a variety of situations where things can go wrong.  It is generally not a good idea to bypass them.  If you are young and usually rushing to cut the grass on a sloping site with slippery clay soil with a mower that doesn’t automatically stop when you take your foot off, then you’d have to be insane to bypass the seat safety switch.  Accept responsibility for your own actions and don’t blame others if you screw up.

Final Thoughts

The reason why such a safety switch design is so effective actually involves psychology.  The average person, when faced with an annoying safety switch, may simply try to unplug it.  In their mind all the ‘clever stuff’ is being done by the switch itself.  They think that by just unplugging the ‘dumb cable’ from the ‘clever bit’ they can stop the ‘clever stuff’ from happening.  When this doesn’t work, they are probably a little bit surprised, then plug it back in and are just relieved that the tractor still fires up.  Nothing broken — whew!

The average person doesn’t have the technical knowledge or confidence to pursue the matter further.  Based on a lifetime of prior experience, connectors are just dumb bits of plastic so there’s no way the connector could have anything to do with the tractor not starting up — they think that an unplugged cable behaves the same as a cut cable (i.e. no electricity goes anywhere).  That means ‘the problem’ must be somewhere back in the engine bay itself and, well, that’s all just too hard.  The simple strategy failed — give up.  People with that mentality are probably the ones that designers are trying to protect from themselves — and rightly so.

Those that do a bit of research, however, find that in order to effectively bypass the switch, they need to actually damage the machine (i.e. cut wires or, alternatively, rip out the shorting member with pliers).  A lot of folks won’t be willing to do that because the idea of inflicting permanent, irreversible (in their minds) damage to something they paid money for is a mental obstacle too high for them to overcome.  Since this issue is likely to arise when the machine is newly purchased, that makes it even harder.  Deliberately damage a brand new tractor — are you crazy?

By moving ‘intelligence’ from somewhere obvious (the switch) to somewhere obscure (the connector), the designers thwart the annoyed masses trying to bypass the seat safety switch.  By making the only workaround one that causes damage, the designers further discourage those that are precious about their tractor.  About the only folk left are the hackers who just don’t give a damn.  If you’ve made it this far you’re probably one of those.  I hope you found this post informative.  Happy hacking!

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Appropriate content warning bypass for Steam apps

Are you a Steam user?  Are you seeing warnings that “Content in this product may not be appropriate for all ages, or may not be appropriate for viewing at work.”  Do they annoy you?  Do you want them to just go away?  If so, read on.

Due to retarded, Nanny State, ESRB policy, Valve is now required to put unavoidable obstacles in the way of users of the Steam store whenever they attempt to access a game (app/whatever) that some precious snowflake, somewhere in the universe, could conceivably be offended by.  They are collectively called “Age Gates” and the one that forces you to put in your date of birth has been around for quite a while.  Not content to annoy people that way, they now are pushing even more warnings for even milder content. /facepalm

The latest warning page looks like this and appears in front of ~10% of the items in my Discovery Queue:

AgeGate

I got sick of seeing that page and clicking on the Continue button repeatedly, so I wrote a single-line GreaseMonkey script to do it for me.  (First World problems — I know.)

Here’s the code:

// ==UserScript==
// @description Effectively presses the "Continue" button on steam app pages that issue the following annoying warning:
// "Content in this product may not be appropriate for all ages, or may not be appropriate for viewing at work."
// @include http://store.steampowered.com/app/*/agecheck*
// @name Appropriate content warning bypass for Steam apps
// @namespace http://localhost
// @version 1
// ==/UserScript==

HideAgeGate(window.location.pathname.split('/')[2]);

All of the lines that start with // are actually comments or configuration directives.  The @include line limits the script to running on only the warning page — this script does not run on any other page.  The HideAgeGate function is passed the appNumber from the URI and then hides the gate for that app — which is exactly what pressing the Continue button does.

If you already have Greasemonkey or Tampermonkey installed, then great — copy the above, create a new script, paste, save and you’re done.  No modification required.

If you don’t know what Greasemonkey and Tampermonkey are, they are extensions that allow you to create and run Javascript scripts that modify how pages appear or work or automate certain tasks.  Greasemonkey started by doing this on Firefox.  Tampermonkey lets you do it on Chrome.  You need to have Greasemonkey or Tampermonkey installed before you can upload and use the script (obviously).

The operation of the script is entirely passive — once you’ve added it to Greasemonkey or Tampermonkey you don’t need to do a thing.  The script detects if you are on that annoying warning page and, if so, effectively clicks the button for you.  You’ll see the warning page come up for a fraction of a second and then go away.  The actual app page that you wanted will then be displayed.

This script was developed and tested on OS X with Chrome and Tampermonkey installed.  YMMV but it’s so basic it should work just about everywhere.

Note:  This script does not do anything on the original age gate — the one that asks you to enter your date of birth.  Other scripts already exist that do that — just do a web search for “steam age check bypass” and follow your nose.

Enjoy!

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