Motion activated and timed staircase lights

Years ago, when I first started with electronics one of the first projects I did was to create some motion-activated lighting on the staircase.

It was a basic setup with stick-on LED lights, activated by a pressure pad under the carpet on the top and bottom step. This is a re-make and update of that project in my new home.

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The lights

I recovered 6 under-counter lights from a kitchen renovation.

The fittings are for G4 bulbs, run off 12V AC, and have a nice chromed finish.

The bulbs were originally halogen, but I swapped them out for LEDs to reduce the power requirements.

As the lights are designed for AC voltage, they can also be driven by a DC supply to simplify the circuitry and make it easier for them to be micro-controlled, so in effect they will be little different to regular LEDs.

The staircase doubles back on itself, so the idea is to mount the lights in the middle partition, and then run the wiring to the control in the under-stairs cupboard. 

Because of the number of steps on the staircase, there will be one light every two steps starting at the second step.

This will put two lights on the bottom half of the stairs, one light on the middle landing, and then 3 on the larger upper half of the stands (as there are more steps on that half).

Routing the cabling

The main difficulty will be in routing the cable for the lights on the upper part of the staircase as it will be difficult to recess the lights without the cable needing to be threaded all the way through. Rather than run the cable all the way through, then have to recess it I opted for a method using the drill as illustrated in the graphic below - this minimizes the amount of material that was removed from the sides and reduces the amount of patching and filler that is required. 

The sensors 

To modernize the switching system, I am implementing a sensor system at the top and bottom of the staircase. I originally intended to use passive infra-red (PIR) sensors, however I don’t want the lights to be triggered just walking past the staircase, and these can be tricky to focus on a precise area.

Instead I’ve opted for ultrasonic distance sensors - not just like the ones used as car parking sensors, but literally those.

These systems typically contain four sensors, a control box, and a small LED display module.

There are several others who've made efforts to interpret the pulsed signal from the control box. I initially tried to follow a similar approach with mine, however was unable to get the example code working - it seems perhaps the sensors I have were either using a different PWM speed or encoding system.

As I do not care too much about measuring the exact difference, and am treating them more like a 'beam-break' sensor, I can take a rougher approach to detecting motion.

After some prodding with an oscilloscope I found a couple of pins that showed a square waveform that appeared to react suitably to me waving my hand in front of the sensors.

I put together a simple arduino sketch to read the rising and falling edge of those waveforms, and simply counted the transitions.

This is a rather effective, but admittedly hacky, solution - basically just observe the range that the transitions are when there's no obstruction in front of the sensor, what the value is when the sensor detects something, and then simply if/else on the value to detect if the sensor has been triggered.

Lighting Pattern and Timing

The lights will be patterned to switch one at a time, starting at either the bottom or top of the stairs (depending on which sensor is triggered), remain on for approximately 10 seconds, and then switch off in the same order. 

The Circuit

The Code

As usual, the code is available on GitHub.

BBQ Grill Tray Handle

With the barbecue grill that I made, I found that I would finish grilling and then want to use the fire pit - which meant that I would need to remove the grill whilst it was still hot.

This gave me an idea for another welding practice project.

Grill tray handles are simply handles which clamp onto the edge of an oven tray so that it can be moved whilst it is still hot.

 

Basically I intend to make the same thing for the grill. 

Using some left over angle bar from the grill, the plan is to create a C-shape, with a bit of flat bar for the lip.

This will latch onto the angle bar that creates the frame of the grill.

This will be connected to a rebar handle, which will provide some mechanical retention by being put through a drilled hole in the angle bar (the translucent bit in the diagram).

I turned some ash wood to go over the rebar, and secured it by welding a thread from a bolt to the back of the rebar, and adding a washer and end nut to secure it in place.

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Flip-top bench for garden storage

Building on from the last fire-pit/patio project, the reason that I was not too worried about the mismatched slabs at the back of the firepit patio was because I knew that the aim was to put some bench seating there which would cover them over.

The slabs at the back were a mix of different styles and sizes to just provide a solid base and gap-fill

 

This project is to build that bench seating.

It will also serve as the new "shed", with a flip top lid where garden tools and such can be stored without needing an actual shed.

The width of the patio between the planters at each end is approximately 12 ft.

While it would have been possible to to get single lengths of timber that would cover the full distance, obviously this would look rather basic. 

Instead we settled on 8ft lengths which would allow us to create a staggered joint similar to that of brickwork, making a much more aesthetically pleasing finish.

We also opted for 2" thick lengths to prevent warping, and add weight and sturdiness.

The height and depth of the bench are based upon the measurements of existing regular garden benches that we already had, so we can be confident that they provide a good seat height. (~16-18 inches).

This is why the there is a mix of 4" and 6" wide.

The open lid and gas strut
(before burning)

The remaining lengths of timber were used to create supports on the inside of the bench, where each of the lengths were joined.

The lid/seat was mounted with 3 shed hinges. Obviously a lid of this size is quite heavy, so to aid lifting it, two boot-lid gas struts from a scrap car were mounted, one at each end.

 

 

The closed bench, showing the latch
(after burning)

A latch and padlock was also added, recessed into the front (so that it didn't catch peoples legs when sat down.)

 

Finally there was a colour difference between the 4" and 6" wood - the 4 being much lighter, so it was burned with a blowtorch so that it would fit in better.

 

Dolce Gusto Genio2 Coffee machine repair

Last year, I was given a Dolce Gusto Genio2 coffee machine for repair.
The owner reported bad water flow, and said that they had attempted to clear limescale, etc using citric acid with no luck, and suspected that the pump was dying.

A quick search showed that there’s an unclogging pin tucked away between the water tank and the machine body. Using that I simply unclogged the nozzle and it worked fine. There’s a good lesson there about trying the simple things before jumping to more complicated conclusions.

Once fixed the owner gave it to me, as they’d already got a new one.

"Before"

Given the wasteful nature of the pod-based machines, and the reputation of the company behind them I took great pleasure in my free coffee machine which I then got some reusable pods for - so despite using one of their machines, I have managed to avoid becoming part of their ecosystem.

 

 

 

 

The main PCB - the bottom connector leads to...

Recently though the machine broke again a couple of times when turning on the lights would blink several times and then go out - shortly after it would just not turn on at all.

I pulled the machine part. iFixit have a good guide to getting the machine apart, so I won’t rehash that here.

After some testing with the multimeter I narrowed the problem down to to the PCB with the power button and the light on.

... the LED fill level board,
which in turn links to the power button board.

It appears that of the three pins, pin 3 is the power, with pins 1 and two being the return line for the red and green LED respectively.

When picking around with the multimeter some more I accidentally shorted pins 1 and 3 and the machine started up, so it seems that the button shares wires with the lights.

With this information in hand further testing indicated that it was the button itself that was faulty.

Unfortunately, there is not an awful lot of space in case for a replacement button - only approximately 2mm. I did not have a button that would fit, but seeing as I cared more about getting coffee then the aesthetics of the machine, I did the next best thing and drilled the hole through the case running wires to the relevant pins.

Then I attached an external button. One that has an integrated LED back light. It is any a single colour though, so I wired it in place of the green LED, so that the button being lit is indicative of the machines ready state.

Then I put the machine back together, and tested to confirm it works.
It's not the most stylish of alterations, but I had no intention of getting another machine, so it was either this or start getting used to instant coffee again.

After

 

BBQ Grill and Coal Tray for the Firepit

BBQ Grill
 

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This project doesn't look like much, granted. However it's a bit of a milestone for me as it's the first real welding project I've done.

It's pretty basic - a frame made of angle iron with bar stock as support, with a steel mesh as the grill itself. The mesh is sandwiched in place to the frame by bar stock - because the mesh itself was too thin to weld (at least, not at my current skill level.)

The cross section looks like this:

 

 

 

 

 

The welding was done with flux-core wire (FCAW - Flux Core Arc Welding, sometimes also known as 'gasless MIG')

Although the welds aren't the prettiest, particularly due to the spatter from the wire (lesson learned - use anti-spatter spray), the frame is plenty strong and sturdy enough for it's purpose, and has been used for several barbecues already.

Coal Tray

 
Because the firepit itself is quite deep, it's not practical to have the coals at the bottom of the pit - they're too far away from the grill. It's also a good idea to have more control over what is being burned when cooking food, so having a separate tray makes sense.

I made this quick tray from aluminium that was left over from the greenhouse that was removed earlier this year.

I had read a few articles warning of aluminium use in food because of health concerns, but this a) seems to relate more to food in direct contact with the aluminium and b) aluminium foil is extensively and commonly used, so one would expect there to be a bigger outcry about it if there was anything to worry about.

Some other aluminium parts from the greenhouse were used to create legs for the tray so that it stands a couple of inches blow the grill.

Beko WDR7543121W Washer/Dryer Repair

Over the Christmas holidays our Beko Washer Dryer stopped working. It was fine for one cycle, and a couple of days later when we went to do another cycle, it just wouldn’t power on.

After checking the obvious things – fuses, sockets etc, I noticed that when first powered (at the wall), there’d be a faint beep – like the key-press beep, but much quieter.

The machine was pretty new, so the first port of call was see if it would be covered under warranty. It’s about 18 months old, so of course just out of warranty. I tried contacting the retailer anyway to see if there was any room for good will support. Of course there wasn’t – planned obsolescence is their business model, after all.

Some online research seemed to point to the mainboard being dead.
Hoping to get things resolved quickly, I found a replacement board and ordered it.

When it arrived the next day, it seemed slightly different to the original – the part number showed “G09” rather than the “G08” that was already installed. I also noticed that although the board layout was the same, some components were either added or removed.

The original board

 
Reasoning it to be a more up to date and optimised version of the same board, I swapped them out.
Booting it up, it seemed positive to begin with – it beeped, the display lit up, and all seemed well.
Everything seemed to work just fine… until I hit start, and nothing happened.

A local repairman who I spoke to advised me that sometimes these boards require ‘programming’ to work with a machine – which is something even he couldn’t help with, as only the manufacturers’ own contractors are able to do that. Basically, it’s like DRM (digital rights management) for washing machines.
Curiosity got the better of me, so I popped the PCB out of it’s enclosure to take a closer look.

On the other side, there was an Atmel ATMEGA – a family of microcontrollers that I’m quite familiar with. It got me wondering if I could dump the firmware from the old board, find what exactly is needed to get the new one working – my guess would be a serial number or other identifier baked in there that I might be able to transfer across to the new board.

However, when I was researching this board, I found another web page hidden away at WasherHelp. It's for a different model number, but I figured worth a shot.

There was references to a diode on the board that failed – The one labelled D7 on the PCB. I checked on my board, and found that the same diode is dead on my board.

I de-soldered the diode from my board, an SR110 schottky diode, and started looking up alternatives. I found that the 1N4002 diode is similar specification, but is a regular diode, not schottky. This was bumping up on the limits of my electronics knowledge, so I asked a friend who has more professional electronics experience, and he told me it would probably be OK, but would likely run warmer and be less efficient.

I also had an 1N4002 on an old PCB in my junk bin. I swapped it in, gave it a test run, and it worked.

I’m happy that I got this sorted, and hopefully will help others extend the life of their appliances. I’m a little disappointed though that I didn’t get a chance to mess with the microcontroller/firmware stuff though. Perhaps another appliance will give me a chance to explore another time.

Disclaimer: This is just what worked for me, and is in no way professional repair advice or instruction. If you decide to do something similar, remember that you, and you alone, are ultimately responsible for the outcome.

Update December 2022:

In case you were wondering - the fix is still holding up. But that's not why I'm updating.

A commenter asked if I had any higher-res photos of the board to help them fix a burnt out resistor. This is the best I could find:

Repair Cafe

I recently started volunteering at a local 'repair cafe'. It’s a community environmental initiative where people in the local community can bring in small broken consumer electronics, and the volunteers will see if it can be repaired, at no charge, in order to keep items out of the waste stream.

If items can’t be fixed on site, advice is given whether it’s worth repairing, and if so what parts, etc. might be required. If they can be fixed, they’re tested to ensure they’re safe, and weighed so that the organisation can monitor the amount of material kept from landfill.

The other volunteers have a wealth of experience in a number of technical and scientific fields, so I also see it as an opportunity to learn and improve my skill set.

I’m also going to keep a record of the repairs I do, and document them here in the hope that it provides a DIY reference for others who may need similar fixes but aren’t able to access a repair cafe in their area.

So, these are the repairs I was faced with on my first day:

• An automatic cat feeder – a simple mechanical clock device turning cogs which in turn allowed a lid on a good tray to open after the set time. The mechanism was reported as being slow. Observation of the device over a couple of minutes didn’t really show any sign of being off, and a test over half hour showed some drift – about an extra minute. The device was far from being a precision instrument though, so suggested that they observe the amount of drift over the time period they’re after and adjust the time they set accordingly.

• An electrical beard trimmer. The mains wire was disconnected. Soldered in place and fixed.

• A DAB digital radio, on which the LCD display wasn’t functioning. Managed to disassemble and retrieve the faulty part, so that a replacement could be found.

• A toaster. The lever to push the toast down was stiff. This seemed to be a design flaw in the toaster, where the lever being pushed down would effectively pivot on the rail where it’s mounted, causing it to bind.
  

  

  
  There wasn’t much that could be done to repair it, but was able to advise the user how to workaround it by keeping the lever flat whilst it was being pushed.
  
  
  
  
  
  
  
  
  
  
  
  
  
• A halogen cooking lamp thing. The timer and the fan would run, but the halogen lamp wouldn’t turn on. Testing showed no power to the halogen connector.
  Tracing the problem back showed that a potentiometer device (pictured) which set the halogens temperature had broken part.
  
  Advised the user of the broken part so they can try and get a spare from the manufacturer to attempt a repair next time.
  
  
  
  
  
  Scorecard
  

  	Score
  Wins	1
  Draws (Workarounds and partial fixes)	2
  Needs parts	2