Burnt out USB charger


It’s one of those horrifically dangerous 2.5×2.5×2.5 cm mini-cube singe port 1 A USB chargers. There were scorch marks on the base of the case. The circuit was very simple, a simplified SMPS on two small PCBs… which held into the cube casing with white silicone/glue – scratch that away and it is easy to extract the pair of PCBs

Continue reading Burnt out USB charger

Strange boiler behaviour


My oil fired boiler is exhibiting some strange behaviour.

Using the control box in my hallway:

  • when I switch on the hot water, I get:
    • very hot radiators,
    • only tepid water
  • when I switch on the heating, I get:
    • boiling hot water
    • only warm radiators

Both tests were after just 15 minutes, with a very cold 24 hours between each test, in order to give the system time to cool down.

Now, logic would dictate that the controls are the wrong way around and that the connections need to be swapped at the junction box.

The additional issue of the additional warming of the water when the radiators are hot, or the warming of the radiators when the hot water is hot could be due to a faulty three port valve.

Continue reading Strange boiler behaviour

Hermes destroyed my Fluke PM3092


Wikipedia states that Hermes is the god of commerce, as well as trickery and thieves (amongst other things). The latter two might be best to describe Hermes – the courier company. In fact Perses would be a more suitable name for the company, as he is the god of destruction.

I had purchased an absolutely beautiful Fluke PM3092 oscilloscope, and was really looking forward to receiving it. When it arrived, in fact before it arrived, before I had even opened the door I heard the delivery guy drop the package on the floor. “That doesn’t sound good”, I thought to myself. When I opened the door, I said, immediately and with a glare, that the package was an oscilloscope and that it needed to be handled carefully. The guy’s face fell. “Ah well”, he cried, as he departed, “Have fun with it!”

Continue reading Hermes destroyed my Fluke PM3092