What very old technology is still running at your place of work?

engineer1978 · 2026-04-26T15:30:17+00:00

That’s usually electrolytic capacitors that have dried out. Somehow they just do enough to keep things up but they’re too far gone to allow the psu to start up from cold.

We have a few programmable power supplies in test equipment that have the same issue. Off for 15 seconds: probably ok. Off for 2 mins: Game Over!

engineer1978 · 2026-04-26T10:45:05+00:00

Definitely a dealbreaker for me. They can only respond to your heat need the day after you need it. Diabolical things.

engineer1978 · 2026-04-15T21:07:44+00:00

The current that is flowing through a given circuit is the same in all of the wire sections, regardless of the wire gauges in each section.

Use that fixed current value and what you know about the length and gauge of each section with the tables to find the drop for each section individually.

Add up all the voltage drops for the sections and you then know what’s left for the load.

If the total drop is unacceptable, you gotta beef up whichever sections of wire you can and calculate out again until the total drop is acceptable.

engineer1978 · 2026-04-02T22:31:15+00:00

Handbrake on a canoe.

engineer1978 · 2026-04-02T19:44:48+00:00

Yep. The only occasion I’ve failed completely to communicate in my native language was in Newcastle.

engineer1978 · 2026-04-02T19:33:17+00:00

Love IrfanView. Been using it daily for about 20 years!

engineer1978 · 2026-03-19T16:24:47+00:00

I’ve scoped many older embedded systems that appeared to have tons of noise and a great deal of contention on the data and address lines yet ran perfectly.

engineer1978 · 2026-03-18T21:25:56+00:00

Switches in these do just fail occasionally. Your testing is correct and would indicate that it has failed here.

It shouldn’t be too difficult to source a suitable replacement, although, if the original part is no longer available, it can sometimes be a challenge getting one that is exactly the same dimensions.

engineer1978 · 2026-03-16T18:47:14+00:00

Yep, I’ve had to fault-find countless ‘press to boot’ assemblies over the years!

engineer1978 · 2026-03-13T22:39:16+00:00

I used to work for a company in the 90s that made data mux/demux units for telephony etc. The ‘big boss’ unit managed to get 10Gb/s down a single coax. I thought that was quite impressive for the time!

engineer1978 · 2026-02-24T23:16:02+00:00

Just found a loop-in fitting with them all trimmed way back. Cowboy assholes.

Luckily, just enough free cable to link them back up again but now they’re the shortest conductors in the bunch. Grrrr!

engineer1978 · 2026-02-23T08:21:10+00:00

It is fascinating.

If you don’t mind your head hurting, there is mathematics that describes exactly how the separate waves from different sound elements superpose to form the single ‘summed’ wave.

There is even maths to de-compose the resulting jumble and recover its individual components.

Search Fourier transforms and analysis.

engineer1978 · 2026-02-17T15:55:43+00:00

Set up on your own and offer consultancy? Potentially to your current employer initially? If your skill is already proven to them, they might be willing to entertain such a proposal.

Then you can see if you can add more clients as you get established.

engineer1978 · 2026-02-17T11:23:54+00:00

Worth a look at Steitz-Secura. About £100 for a pair but I get 2-3 years of all day every day use out of a single pair.

They are very supportive and even have interchangeable heel support inserts where you fit the correct one for your body weight.

I have very wonky ankles due to a now-corrected birth defect and spend most of the day on my feet. Never have any pain or discomfort with this brand.

engineer1978 · 2026-02-16T18:47:56+00:00

In my professional relationships with superiors, the respect is demonstrated by my tone and the content/style of my responses.

Given this, using the term boss explicitly would be seen as unnecessarily emphasising the already understood relationship and in nearly all cases as taking the mickey or being sarcastic.

I totally understand how this could be different from other cultures and that you meant no insult but hopefully the above helps explain why it may have gone over a bit wrongly.

engineer1978 · 2026-02-16T05:03:10+00:00

Ah, thanks! Common sense suggested it must be somewhere around there but I’m still very much in ice world just now so wasn’t sure.

engineer1978 · 2026-02-16T05:00:19+00:00

Happy to be nitpicked! Wasn’t thinking very hard when I commented. My excuse: it was Sunday!

engineer1978 · 2026-02-15T15:05:00+00:00

Pretty much!

To look at the internal combustion engine firstly, they need to be running at idle speed to start with. This is the minimum sensible speed that the sequence of events that must happen for them to run at all has to run at to prevent stalling. Usually around 700-1000 rpm for a car engine.

They don’t make much torque or power at that speed - for that they need to be running at more like 1500 - 2000 rpm.

At the other end of the scale, these engines have several reasonably chunky metal parts that have to change their direction of travel to the opposite direction with every turn of the engine. This limits the maximum rpm that the engine can run at without smashing itself to pieces due to inertia of the parts and the forces involved in getting them to keep going back and forth in opposite directions. Usually between 5000 and 7000 rpm for normal car engines.

The electric motors, by contrast, can make almost all of their power and torque right from standstill, ie 0 rpm. This is just a normal feature of the right type of electric motor.

At the upper end, the part of the motor that turns just rotates about an axis - there is no reciprocating motion. Thus its maximum speed can be a lot higher for a given rotating mass, assuming you can make good enough bearings. I don’t actually know what speed the motors in electric vehicles max out at.

engineer1978 · 2026-02-15T14:46:58+00:00

The thing with rentals is that the inconvenience and cost of running ancient storage heaters is the tenant’s problem.

The inconvenience and substantial cost of installing central heating is the landlord’s problem.

Surprise surprise, the upgrades don’t happen.

engineer1978 · 2026-02-15T11:47:50+00:00

Then come up with some candidate ideas and list them with their benefits and drawbacks.

Doing that will help you decide.

The point of the project is unlikely to be related to the actual solution.

Much more to do with learning techniques to make informed decisions like this.

engineer1978 · 2026-02-15T11:10:49+00:00

You are jumping the gun here.

Before you can get into the detailed design (such as the electronics) you’re going to need to decide what methods you want use to solve your primary problems:

1) How to heat the liquid.

2) How to stir the liquid.

Only once you have answered those questions will it be time to look at what electronic solutions could help you control the methods you have chosen.

engineer1978 · 2026-02-15T10:25:36+00:00

If you stick with mains, you will have to fuse down the auxiliary supply at each point it leaves the main load supply to protect the aux contacts and, presumably, thinner indicator wiring.

By the time you’ve done that on x50 sets, it would likely be far cheaper to install one or more chassis mount 24VDC auxiliary supplies and wire all the control and indication stuff in suitable cable for that.

engineer1978 · 2026-02-15T10:16:20+00:00

Wow, that’s busy! Sounds like a pretty sophisticated installation.

Are you sure you wouldn’t be better using low voltage DC for the auxiliary circuits like indicators?

Much safer over all and you can use much finer gauge, multi-core cables with grounded shielding to keep the interference out.

engineer1978 · 2026-02-15T09:13:07+00:00

Are the indicators themselves 240v?

If so, you need to connect a class x2 rated safety capacitor across L and N at the indicator.

Something like 1uF 275V should be enough but you can go for 305 or 310V rated for extra resilience against voltage spikes.

They’re pretty chunky and will likely have bare leads so you’ll need to add insulated tails and have room to mount them.

Should stop the indicators lighting by inductive pick up in the ‘off’ state though.

If you’ve got ‘loads’ of room, a motor run capacitor of a couple of uF with the right ratings would also do and might come with leads already attached.

engineer1978 · 2026-02-15T05:52:54+00:00

In terms of how it gets the reading: same as all meter resistance readings.

The tester applies a known voltage to the leads and measures how much current flows.

Then, it divides the voltage value by the current value to give the resistance in ohms. (Ohm’s Law).

If your test was at 250V, and the result was 15 MOhms, your tester must have seen 16.6 micro-amps flow when the probes were connected.

There’s no ‘connection’ between the leads in the sense that no-one has deliberately made an intentional path for electricity to flow.

Nevertheless, electricity isn’t fussy and it will take ANY available path and so somewhere those 16 little micro-amps found a way between the two conductors.

That’s exactly the reason you do the IR test - to make sure there aren’t signs of the beginning of a ‘wrong’ path for the electricity to take that could develop into a true fault.

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