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Tuesday, 18 July 2017

Classic Mini LED indicator (turn signal) lamp replacement.

Still working on the Mini. It's coming along nicely, albeit slowly...

I did have a plan to reassemble things in a nice orderly manner. That's long gone out of the window! The best plan seems to be this:

1) Remove a part from the box.
2) Identify part
3) See if we can if the part, and if so
4) Clean/ paint the part and fit it.

With this in mind, it's recently come down to electrics.

Now the front indicator (turn signals if you're across the pond) / side lamps housings were made by lucas 39 years ago, from a sort of Mazak "monkey metal". Now this alloy doesn't age well, and mine were starting to crack up. Sadly there are long since obsolete, and good original ones now command a high price. Lenses are still available, however.

There are a couple of reproductions available. Some are quite expensive. Most seem to be made from ABS plastic of some description. Ideal. I chose these from Spyda designs, simply on price! (£31ea at the time of writing). Link Here . (Image stolen without permission from Spyda designs, sorry)

They rapidly turned up, nicely packaged.

They are quite a lightweight flexible construction, but this is no problem in use. They fit really well.

Nicely constructed, the PCB features three 1W yellow LEDs for the indicator section, and one 1W warm white, wide angle LED for the sidelight. The observant amongst you will notice there's a TO220 device in the top right hand corner, I suspect it's an LM317 or similar configured as a constant current source for the LEDs. Far better than a dropper resistor, and should ensure our LEDs have a good, long life. Great stuff!

The problem with fitting LED lamps is the dear old Lucas flasher unit buried under the dash. It's a thermal bi-metallic strip kind of thing, and relies on the current drawn by the lamps to operate. A normal flasher bulb is 21W ... these indicators are 3W .... the Lucas flasher unit just doesn't flash... it just stays lit up. This problem is exacerbated by the fact I've installed LED lamps in the rear too...

Because Mini didn't really change much with the times, there's another flasher unit by the windscreen wiper motor too! It's job is purely for the hazard warning lights (Four-ways if you're in the states!) This doesn't work either.

Now we could just shove in some 21W 6.8 Ohm resistors in the circuit in parallel with every indicator lamp (we would probably get away with 10W, as the duty cycle is about 50%), but that's a horrible bodge really.

OK, I thought about a simple 555 timer or discrete astable multivibrator driving a relay, until I looked on eBay. LED compatible flasher relays are no money ....
OK. So I ordered a couple to replace my two relays.... one turned up. Typical. (I've contacted the seller, the other is on it's way!!)

Now our dear old Lucas unit has two pins (actually some have three, but only two are connected), and doesn't give one iota about which way it's connected. This new unit has three pins, and I suspect it transistorised somewhere along the line, and is therefore going to get upset if we wire it up backwards.

The three connections are as follows....
L - Lamp - goes to the indicator lamps.
E - Earth - goes to chassis ground.
B - Battery - goes to the battery.

Only, of course it's not quite that straight forward. If we wired it up like that, our indicators would be permanently flashing, day in, day out....

So .... a quick consultation with the Haynes manual, and a poke round with the multimeter are required....

I will point out at this juncture that Mini had a long production run, from 1959 to 2000. Along the way some improvements were made to the electrics (and some of it wasn't!!). You may have a positive earth car if it's from the 50's or 60's ... you may or may not have hazard warning lights... and of course, Mini was exported all over the world, so local requirements would have changed the wiring...

Anyway... the original Lucas flasher was located hiding under the dash rail....












It's that round tin thing .....












... duly removed...












One side connects to a light green/ red wire. This is in accordance with the Haynes manual... good.











The other wire is blue with a red stripe. It *should* be a solid dark green. I can see further up the loom, that a repair has been made, and it does indeed join onto a green wire....








Now this is where things get a bit confusing. Having thought about this, I (mistakenly) thought this wire would simply supply 12V, via the indicator switch to the relevant lamp. Nope, there's a permanent 12 Volts there.... damn. This is why I have a hated for car electrics diagrams. None of the switches show a position. Scroll back up to the photo of the diagram, and have a look. 26 is the indicator direction switch. 25 is the flasher unit. 153 is the hazard warning light switch. 31 & 31 are the indicator lamps. There's obviously something missing. Some lucas magic going on in the hazard switch? There's no such thing as magic....

No, here's what happens. 12 volts gets to the original flasher unit. It's output goes to the lamps, via the indicator direction switch. Once the switch is made, current is drawn through the lucas flasher, which starts to warm a bi-metallic strip inside the unit. Once it's been on for a second or two, the bi-metallic strip opens the circuit, and starts to cool as no current is being drawn. Once it's cool, it closes the circuit again, and the process repeats.

Right, but what happens to my new flasher unit, if it's getting a supply (and earth) simultaneously? Is it going to sit there clicking away, annoying the hell out of me, even when my indicators aren't on?

As it turns out, no. It actually needs to see a load to operate, exactly like the old lucas unit. Just not much of a load!

So, the dark green wire goes to B, and a new earth wire goes to the chassis and pin E.

Works a treat....

The hazard warning flasher is wired up the same, and works flawlessly too..

Light green and brown goes to L, and the wire from the inline fuse holder, connects to B.

How, back to work.... ;)

Thursday, 29 June 2017

Mini 1275GT reassembly and electrolysis of rusty parts!



Here's a few pictures of what's been absorbing most of my time lately....






















It doesn't look like much, but there's all new brake lines fitted, lots of parts cleaned and painted and reunited with the car!

To clean up a lot of the metal parts, I've taken to electrolysis...

This involves making a mixture of about 10% ordinary washing soda (you can get this from Sainsbury's in the UK, £1.20 in my local store for a 1kg bag) and tap water.

You'll need a nice clean piece of ordinary mild steel (Don't use stainless). I used a plate, you can see it in the centre of the tank. And you'll need a power supply (I used my adjustable bench supply)

Connect the clean steel to the positive terminal, this becomes our sacrificial anode. You'll probably realise from the name, that this isn't a piece of steel you'll want to use again....



Attach the rusty part to the negative pole, and drop it in the tank.... Keep a small distance between the part and the steel plate.

Switch the supply on, and adjust the voltage until a bit of current flows. Small bubbles will rise to the surface. I found good results with about an amp of current flowing.

You'll want to do this in a very well ventilated area, as the bubbles are hydrogen and oxygen, and PLEASE switch off the supply before adding or removing things from the tank, a spark could ignite the gas.....

After a new hours remove your once rusty part.

You'll need to clean off the solution, dry it and paint it to prevent it rusting rapidly.



What's happened to the rust? It's on the anode ....

This is after just a couple of days of use... you can clean it up with a wire brush or grinder and it'll go again :)

Simple Arduino Thermostat with MAX7219 Display and DS18B20 sensor

Just shows how these jobs snowball....

James had seen Oto's dehumidifer controller, and said "I need something to monitor and control the temperature of my honey warming cabinet" (it's a beekeeping thing!)

A simple thermostat, with a nice clear LED display, and adjustable set point was born ....


You'll see the code, and most of the schematic is very close to the dehumidifier controller, so I'll not dwell too much on that.. the main difference is the use of the MAX7219 7 segment display, previously used on the GPS clock, and the DS18B20 temperature sensor, which I'd previously used in the pond pump controller.

Here's the code:





Ryan built up a nice enclosure....

















... and, in a stroke of genius, added a strip of red PVC insulating tape to improve the contrast of the display!
















Thursday, 25 May 2017

Sony Xperia Z5 Compact Camera replacement.

I've had my little Sony phone for a while now, and it has been superb....

... until the other day when the camera started to play up....


Hmmmm, not ideal.

If you put some pressure on the phone, around where the camera lens is, it would come back to life for a few seconds, sometimes with some bizarre effects...

.. not ideal at all....

I thought I could live without it, but after a week or so, I realised how much I used it for taking quick pictures of wiring etc ... I decided
I'd need to investigate, so I googled disassembly instructions, but couldn't find a video or instructions that had the same layout as my phone.

I removed the back of the phone and quickly diagnosed that the camera module itself was at fault (I was hoping some connector had just come lose, no such luck).

A new camera module was sourced from eBay for a princely some of £13.95 delivered... I ordered a replacement adhesive gasket kit as well (£2.45)




So here's how it's done...

Switch the phone off, and gently heat up the back of the phone with the wife's hairdryer or a heat gun set to low.











Get a sucker and a prying tool and gently remove the back. If it doesn't come away easily, heat it up a bit more. Don't risk bending the metal back....









Right, that's good.














Un-latch the NFC aerial connector at the end shown ....











... and lift it out of the way.














Unscrew the small pozi screws retaining the aerial module .....























... remove it, and place it to one side.













Undo all the screws on the plastic frame .....











... gently work a small insulated tool (this is a ceramic screwdriver) under the flash LED (it's retained with a small blob of adhesive) ...










... and hinge it out of the way.













Carefully prize the plastic frame out. The flash LED should slide through the frame.










Excellent.













Just for piece of mind, disconnect the battery.













Now prize up the camera connector....












... and remove the camera.











Worryingly, the new camera didn't come in ESD safe packaging....












... and was supplied with some sort of rubber gasket, which the original camera didn't have, I just slipped it off...










Some careful bending of the camera's ribbon cable, and it all fits in, and the connector is pushed home.

Now put the phone back together again. When fitting the frame make sure the flash pokes back through, and the NFC connector doesn't get trapped.

Replace the adhesive gasket, and replace the back...


... and go and take some photo's !













Got my thumb in as usual .... ;)



Friday, 19 May 2017

Return of the Arduino Dehumidifier controller.

My very good friend Oto has a problem.

He's moved into a new house.

He's wanted some space for his lathes & mills etc, which this has.

 After a few weeks, his machines are showing signs of going rusty.... Why is this?

 It's humidity.. after installing a dehumidifier, things have improved dramatically, except his electricity bill...

 It's time for a slightly revised version of the first project I did on this website back in May 2014 (where does the time go??!?)

It's got a similar display, except it's in Czech, but it has an adjustable set point for humidity, and a mode switch to set between auto , whereby it switches on 5 degrees C before the dew point, or manual, where it switches on when the desired humidity set point is reached.

The mode switch is S2 on the diagram below, and S3 is a centre-biassed momentary toggle, which is used to alter the set point up or down.

The set point is stored in E2PROM, and is restored in the event of power failure.


The temperature and humidity is read from a DHT22 sensor, and the dew point calculated.

The dehumidifier is switched on with a suitable rated relay, via T1.

Here's the code:








... hope Google's translate has done a reasonable job!