Rick's b.log - entry 2023/09/21

SimpleSeq v0.08

Yeah, me too.

But, like Columbo, there's always "one more thing".

I fixed a really trivial bug, and added this:

Filters to apply to the music.

As for a user manual, well... read this and this and this and this and this and this and finally this. Phew!

UV bug lamp failure

Duff UV tube.

The box proudly said that it was "environmentally friendly". It's a bit of greenwashing because it doesn't use chemicals (thus environmentally friendly) but the user guide says that the lamp is fixed and is non-serviceable. So if it gives up after a mere few months, you're supposed to bin it and buy a new one? How is that in any way environmentally friendly?

It's also complete crap. It's a tiny 4W UV tube. Their type number is "F4T5". You can find them on the usual tat bazaars. Two will be arriving here on Monday, more or less (it was sent from Barcelona this morning).
Fair enough, they probably don't want to have dumb people trying to replace the bulb when the HV is powered up, but wouldn't an "unplug it you moron!" warning suffice?

As I had the unit open, I took the time to give the grille a good clean to remove all the dead bug bits.

The insides and the HV cage.

And here's the circuit.

Bug zapper circuit.

Typical tube drivers use an inductor to limit the current flowing through the tube. It looks like this is just using a basic capacitive dropper because it's cheaper, coupled with an actual starter (upper right) to give it a kick if necessary.
It's a rather icky way to drive a fluo and probably why it didn't last that long. It's also not going to get much in terms of strike current. I'd imagine the only reason this works at all is because the tube is tiny and the HV cage around it will be blasting ions around before the starter has even had a chance to engage.

Suffice to say, there's a reason this was cheap...

As for that cage, charged capacitors and diodes to act as a basic voltage tripler. It'll take the AC input and create a high voltage DC(ish) output. The peak voltage for 230V mains is 325V. Times three, that's 975V. But let's say 950V because there will be losses in the components. Ripple will be horrible, but it'll be pulsing those volts far faster than the reaction time of a bug.

It... actually seems to be rather useless against flies because they aren't pathologically wired to dive headlong into the nearest light source.
Moths, on the other hand, are. And it's taken out plenty of those.

Not going to Nantes

However earlier in the year I read news reports about a rise in the prevalence of bed bugs. It seems two places particularly affected in France are Paris and Nantes, but bed bugs seem to be on the rise in general - maybe it's weather related?
Whatever, it kind of put me off wanting to use public transport.

So I stayed home. Apart from the odd spot of bramble slaying, I basically just worked on SimpleSeq, writing this rubbish, and watching Netflix. Took it easy, in other words.

I'll probably pop down to Big Town tomorrow or Saturday.

Cooler mods

I have also discovered that it's pretty good with just a €1 bag of cheap frozen veg on top. But it would be nice to engage the fan without the cooler to help circulate the cold.

Opening up the lid, I see this inside.

Cooler original wiring.

That makes it easy.

I split the positive wire into feed, fan, and cooler wires.
The feed goes to one chunky switch. From this emerge the power to the fan and power going to the second chunky switch, which turns on the cooler.
It is done like this so it isn't possible to run the cooler without the fans.

The hard part was putting the holes in the case for the switches. I made two dents in the plastic for the centres of the switches, then used an 8mm wood drill to make the holes. As the switches were rather more than 8mm, I had to use a pair of scissors to gouge the holes a bit larger.

Cooler new wiring.

Reassembling the cooler, it now has two switches to the upper left.

Switches.

The left switch is for the fan, and the right one is for the cooler.

Close-up of the switches.

And...

I think it's about to rain, quite a lot, and I have to sort out the rubbish and recycling. Hmm...

That's a dark sky.

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John, 21st September 2023, 17:08

We bought a cooler like that, left it in on the ferry, had to have the flat car battery "boosted" to drive off, and had to drive to our destination without power-steering. Our 'garagiste' located and replaced the blown fuse.    It was the momentary reverse-polarity of the charger as it wasn't very bright on the car deck (and neither was the "docker"), and weren't we lucky that was the only damage done considering all the electronic wizardry in "modern" cars!    We never used the cooler box again. Once bitten!    Peltier device sounds very trendy, but is not terribly practical!      I thought every day was Mop'n'day at your work!

David Pilling, 22nd September 2023, 12:41

A bit like peltier, there are a lot of ultraviolet LEDs looking for a problem. Seemingly a common fraud are uv LEDs. Bananas then enter the picture as a test - developing a sun tan under uv or glowing blue.

JGH, 24th September 2023, 20:52

"doesn't use chemicals"? But glass is a chemical, the nitrogen in the tube is a chemical, the plastic caps are chemicals, the copper wiring is a chemical. I'm amazed you've found a lamp composed solely of shaped energy!

Rick, 24th September 2023, 23:31

Yes, reality is made up of chemicals.  What was meant was that it wasn't a noxious spray intended to kill anything it touches...

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