Super sunset

This was the sunset on Thursday night in Woodstock. I wasn't the only person out photographing it. Then I found this article. Woodstock is about as far from the sea as you can get in the UK. If salt was enhancing the sunset colours it would be impressive.

Good example of the need for an earth connection

These old-fashioned radiant heaters are regarded as dangerous these days. The modern convection heaters are much safer. Once I used to use these as a good example of the need for an earth connection. The case has to be made of metal so that it doesn't melt. However if the live connection comes lose and touches the outer case, you would complete the circuit to earth if you touched the case and would get a nasty shock. So the earth wire is soldered to the case. If the live wire comes lose and touches the case, the current follows the route down to earth. It is a low resistance route so the current is high enough to blow the fuse and make the device safe.

Microwaving my soup

I had no idea how long to set the microwave for my soup so I did it in short bursts to avoid an accident. I realised later I could do a rough calculation. I used half of 600g container, so mass is 0.3kg. Let's assume it's water. From fridge to boiling is 95oC temperature change. Energy = m. c. Delta Theta = 0.3 x 4200 x 95 = 120000J to 2sf. I used 900 Watts so 900 Joules per second. Time would be around 2. 25 minutes. But allow for heating the bowl and unknown efficiency then 3 mins would be a decent starting point next time. 

Shredder switches

 I did manage to fix the shredder - a little victory but was bamboozled for a while by why it wouldn't turn out. Turns out that there are 3 switches that must be wired in series. The switch you press to turn it on is A. Switch B means that the rotor won't run unless there is paper in it. The paper pushes down at B on the black plastic arm that pivots, pushing inwards to close the switch. When that paper has shredded, the arm pops back out and the motor stops.

But there is a third switch that is only activated by putting the shredder into the waste tub so you can't operate the shredder away from that tub.

Shredder induction motor

 The shredder got stuck and needed surgery.

Looks like an induction motor. It has an ac supply so the electromagnet coils produce an oscillating magnetic field through the rotor coil. This induces a current which pushes against the magnetic field by Fleming's Left Hand Rule..

Cleaning the waste ink pads on a Canon Pixma MG 2950

 My Canon MG 2950 was a sturdy and dependable printer. It lasted for years. Then I got the waste ink pads full message. It is possible to keep going after that by pressing the black print button when prompted. But that finally ended last week. So faced with the option of having a go or giving up and buying a new one, I had nothing to lose so I decided to see what the fuss was about. I got in by taking out the two screws by the paper feed. Then you unhook a catch above where the paper comes out and push the top back to release two further catches. The electric feed ribbon to the top comes out. The waste ink pad is A. Undo screw B to release.

I tried soaking in a bowl - lovely diffusion experiment - but under a running tap was best.

This is it dry.

This is it back in.

Wonderful chromatography.

Sadly I then got code 5012 which was terminal. If you get code 5B00 then there are good instructions online for a reset. Sadly didn't work for me but it was fun trying.

Mid-winter sky

Mrs B found this wonderful APOD last week covering the part of sky in the photo and showing the nebulae. Our southern sky is the one with street lights so I'll have a better look when we are somewhere with a darker southern aspect.