Tricks of the Trade - knowledge for every day life

[Sal Ammoniac]

Yep, I used to use ferric chloride to etch the date back on a certain type of US 5C. The dates were at a high point for wear and "dateless" nickels of this type were common. You could, however, etch the date using ferric chloride. To keep the ferric chloride right around the date area, I would use a permanent marker to make a border. After the date was revealed, acetone would remove the marker.

The same technique is used to reveal the serial number on guns where the number has been filed down.

[VK3DRB]

Best thing I learnt in electronics that helps with everyday life is CONTROL THEORY. It is part of all engineering degrees and it is arguably the most useful subject of all. We use it in electronics design, but control theory maps out to most things we do in life. During COVID, applying control theory increased my wealth significantly. Control theory has helped me understand the spread of the virus and predict the lock downs a lot better than most people. It is unfortunate that most politicians and their advisers in Australia do not apply control theory to their decision making. In fact there are instances where they clearly have demonstrated they do not understand it.

I don't overreact to negative feedback, and positive feedback is neither here nor there .

[EEVblog]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

[IDEngineer]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

REALLY? That could be exceptionally useful....

Escaping (really, expanding) gas drops in temperature, of course, but I didn't know that inverting the can would make a difference. Must try that immediately!

[AlfBaz]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

LOL.
Just  saw this this thread and as I was reading through it I thought to myself no one's mentioned the upside down can trick yet, I'll add it.

Just to add to that, freeze spray upside down can be used as compressed air

[langwadt]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

REALLY? That could be exceptionally useful....

Escaping (really, expanding) gas drops in temperature, of course, but I didn't know that inverting the can would make a difference. Must try that immediately!

when you invert it it spray liquid instead of gas, so it evaporates on the part instead of in the can

[Kasper]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

REALLY? That could be exceptionally useful....

Escaping (really, expanding) gas drops in temperature, of course, but I didn't know that inverting the can would make a difference. Must try that immediately!

when you invert it it spray liquid instead of gas, so it evaporates on the part instead of in the can

I've done this with 'air duster' cans marketed for cleaning computers.  People were using them to get high so they added a noxious scent to it.  That scent lasts a long time, transfers from surface to surface and tastes bad.

I know we are not supposed to taste our electronics.  I am pretty clean and fairly neurotic about washing my hands when working with electronics but somehow it got passed my defenses.

[Kasper]

I've done this with 'air duster' cans marketed for cleaning computers.  People were using them to get high so they added a noxious scent to it.  That scent lasts a long time, transfers from surface to surface and tastes bad.

I know we are not supposed to taste our electronics.  I am pretty clean and fairly neurotic about washing my hands when working with electronics but somehow it got passed my defenses.

For the record, I did not huff it.  I live in BC, we have much better stuff to puff out here.

[Psi]

Just be aware that a small number of airdusters/compressed air cans use a different feed system inside, which does not work to get freeze spray when upside down.
(Same tech used in those spray paint cans that can spray upside down.)

[Cerebus]

In the vein of "knowledge for everyday life":

When making flaky pastry, after combining the fat and the flour, chill the combined fat and flour mixture with the mixing bowl and the water you're going to add to it in the fridge for an hour before moving on to the final mixing stage. This minimises the formation of gluten when you wet the flour and makes for the lightest, crumbliest pastry.

(Not too hard to guess what I'm spending my Christmas Eve doing.  )

[tooki]

There’s a reason some recipes specify using ice water.

[Cerebus]

At the moment I'm more minded to be following the medieval recipe for meringue that I once encountered "Beat the egg whites until you have exhausted three servants". In this case the bit I'm minded to be following is the "having servants" bit. [Flops onto sofa.]

[langwadt]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

REALLY? That could be exceptionally useful....

Escaping (really, expanding) gas drops in temperature, of course, but I didn't know that inverting the can would make a difference. Must try that immediately!

when you invert it it spray liquid instead of gas, so it evaporates on the part instead of in the can

I've done this with 'air duster' cans marketed for cleaning computers.  People were using them to get high so they added a noxious scent to it.  That scent lasts a long time, transfers from surface to surface and tastes bad.

the nonflammable kinds used to be (and some still is I think) R134A, the refrigerant they are facing out because it is 1500 times worse than CO2

[Berni]

Here is another trick i use freeze spray for: Recharging cans that ran out of air only.

We use various canned stuff stuff like PCB Cleaner or WD40, but we all know when the you run out of air so the can won't spray but you can clearly hear the liquid still inside. What i do is stick the straw of the freeze spray into the other can (Sometimes it just fits, something it needs to be held against it) then press down on the freeze spray, then the empty can. This starts transferring the freeze spray over into the empty can, all you need is to hold it for a few seconds. Now that can of WD40 sprays like new again.

I tried this before with an air compressor, and it does work too, but since the air can't be liquefied in there means that you get a lot less gas volume to fit so the air runs out again fairly quick.

when you invert it it spray liquid instead of gas, so it evaporates on the part instead of in the can

I've done this with 'air duster' cans marketed for cleaning computers.  People were using them to get high so they added a noxious scent to it.  That scent lasts a long time, transfers from surface to surface and tastes bad.

the nonflammable kinds used to be (and some still is I think) R134A, the refrigerant they are facing out because it is 1500 times worse than CO2

Yeah the KontaktChemie freeze spray had quietly changed at one point. Branding it as a new improved formula when in actuality they just got banned from using the older refrigerant gas. The advertised cooling temperature also changed slightly, you can use that to find what refrigerant boils at that point at sea level.

[coppercone2]

careful with freeze spray I broke precision op amps before with condensation. You need a dry environment don't do it when its humid.

[Psi]

You can push the ground spring attachment onto the end of the scope probe with a wire trapped under it.  Very useful when you want to probe something that needs a very short GND connection and you need it to be soldered for 'hands free'.

[armandine2]

Real and Imaginary

which is which

https://www.amazon.co.uk/Metrix-MTX3291-Digital-Multimeter/dp/B01M61RW39

especially in purchasing

[Kasper]

bicarbonate of soda/baking soda and super glue make an instant drying hole  filler

Put the powder in the hole first, then drip superglue on, don't try and make a paste and push the paste in, it sets in seconds. Also it gets HOT!.

Just came across a video that reminded me of this one.  They do a bit of destructive testing, repair stripped head of screw and even mold a wrench. 

Another trick here is to use WD-40 as a mold release spray.

Super Glue and Baking soda! Pour Glue on Baking soda and Amaze With Results

[xmris]

Make bases for small bottles - like flux/lubricants - using foam packaging sheets.
It will keep them stable and no more mess on your workbench

[eti]

Always *twist* a stranded wire and then solder saturate it into a solid end (and then clean off any flux) and then cut it flush and clean at the tip, before screwing into a terminal block. If possible use captive terminal types, the ones with the ridged moving flat clamp which rides up and down with the screw and applies even pressure across the wire end, otherwise excess tightening causes screw-shaped pits in the wire end, and if it’s not been soldered as above, you get little copper strand ends falling out everywhere, which not only means short circuit risk but means the cross-sectional amperage rating of the end has decreased.

[eti]

Especially pertinent to consumer goods servicing:

ALWAYS ALWAYS thoroughly clean a piece of equipment before returning it to the customer. It’s a matter of pride in one’s work, and shows the customer you pay attention to the little details. We used to use “Ambersil” foaming cleaner to give our TVs a good scrubbing of tar and grime, before sending them back into their dirty homes to pick up a fresh lot. 😄

If your a subscriber to “Mr Carlson’s Lab” on Patreon, he has an excellent video on how to run a repair business, and his ethics PRECISELY align with mine.

[KE5FX]

Always *twist* a stranded wire and then solder saturate it into a solid end (and then clean off any flux) and then cut it flush and clean at the tip, before screwing into a terminal block. If possible use captive terminal types, the ones with the ridged moving flat clamp which rides up and down with the screw and applies even pressure across the wire end, otherwise excess tightening causes screw-shaped pits in the wire end, and if it’s not been soldered as above, you get little copper strand ends falling out everywhere, which not only means short circuit risk but means the cross-sectional amperage rating of the end has decreased.

The problem with that is that solder will cold-flow, potentially enough to loosen the connection over time.  When clamping stranded wire into a terminal block or wrapping it around a screw terminal, I prefer to twist the strands together and then apply solder only to the end of the wire, using just enough to keep it from fraying.  Haven't had trouble with the strands breaking, myself.

[eti]

Always *twist* a stranded wire and then solder saturate it into a solid end (and then clean off any flux) and then cut it flush and clean at the tip, before screwing into a terminal block. If possible use captive terminal types, the ones with the ridged moving flat clamp which rides up and down with the screw and applies even pressure across the wire end, otherwise excess tightening causes screw-shaped pits in the wire end, and if it’s not been soldered as above, you get little copper strand ends falling out everywhere, which not only means short circuit risk but means the cross-sectional amperage rating of the end has decreased.

The problem with that is that solder will cold-flow, potentially enough to loosen the connection over time.  When clamping stranded wire into a terminal block or wrapping it around a screw terminal, I prefer to twist the strands together and then apply solder only to the end of the wire, using just enough to keep it from fraying.  Haven't had trouble with the strands breaking, myself.

Good point re only the end. But the gold standard of stranded wire termination for terminal block insertion is crimp ferrules

[mikeselectricstuff]

Don't know if it's already on here, but turning a can of compressed air upside down turns it into a handy freeze spray for detecting faulty components.

And often vice-versa- can of freezer upside down can give an air blast, depends on type though

[mikeselectricstuff]

1mm pitch ribbon cable crimps nicely into RJ45 and RJ11 connectors - handy if you need some short, very flexible ethernet cables.