Tricks of the Trade - knowledge for every day life

[KE5FX]

Here is one:
PCB Cleaner spray (the usual isopropyl and ethanol mix) used to clean flux off your boards is excellent at removing hot glue from pretty much any surface.

Just soak the blob of hot glue in the stuff, leave it sit for a few seconds than pry at it a bit while its still wet, the hot glue suddenly looses all adhesion and just falls off, but it doesn't seam to dissolve the hot glue at all so it does not make any mess.

Pro Tip #1: Instead of hot glue, use UV-cure adhesive, available at most hardware stores and stores that sell fishing supplies.  Apparently it's used for fly tying, or something like that.

Then, throw away the LED light that comes with the adhesive and replace it with a 405-nm Chinese laser pointer.  These are sold on eBay by the dozen for around US $1 - $3 each, and range from 5x more powerful than they're supposed to be to 20x more powerful.  Unlike the LED, the laser can penetrate some distance into a large blob of the material, making it a good substitute for hot glue.

Pro Tip #2: Wear a good pair of sunglasses when performing Pro Tip #1.

[jogri]

Pro Tip #2: Wear a good pair of sunglasses when performing Pro Tip #1.

Please don't do this unless you want to experience what permanent blindness feels like. You have no idea if and by how much sunglasses reduce the intensity, and with 405nm being visible i don't think that sunglasses will block it. If you are stupid enough to stare at the spot long enough you will probably fry your cornea, and for what? A faster way of curing epoxy that sucks because you can only hit a tiny spot? If you want it to cure faster get a UV lamp... More power, and it isn't nearly as stupid as using a laser.

Btw, you can get decent laser goggles for 60-70 bucks, and with those you know excatly which part of the spectrum they block to what extend. Using sunglasses because they "block light" is just beyond stupid, those things are absolutely NOT designed to handle extremely strong, collimated light.

PS: Rule No.1 of laser safety: If you can see the laser, you done f**ed up.

[bsfeechannel]

Pro Tip #2: Wear a good pair of sunglasses when performing Pro Tip #1.

Please don't do this unless you want to experience what permanent blindness feels like. You have no idea if and by how much sunglasses reduce the intensity, and with 405nm being visible i don't think that sunglasses will block it. If you are stupid enough to stare at the spot long enough you will probably fry your cornea, and for what? A faster way of curing epoxy that sucks because you can only hit a tiny spot? If you want it to cure faster get a UV lamp... More power, and it isn't nearly as stupid as using a laser.

Btw, you can get decent laser goggles for 60-70 bucks, and with those you know excatly which part of the spectrum they block to what extend. Using sunglasses because they "block light" is just beyond stupid, those things are absolutely NOT designed to handle extremely strong, collimated light.

PS: Rule No.1 of laser safety: If you can see the laser, you done f**ed up.

That would be Pro Tip #3.

[Berni]

Here is one:
PCB Cleaner spray (the usual isopropyl and ethanol mix) used to clean flux off your boards is excellent at removing hot glue from pretty much any surface.

Just soak the blob of hot glue in the stuff, leave it sit for a few seconds than pry at it a bit while its still wet, the hot glue suddenly looses all adhesion and just falls off, but it doesn't seam to dissolve the hot glue at all so it does not make any mess.

Pro Tip #1: Instead of hot glue, use UV-cure adhesive, available at most hardware stores and stores that sell fishing supplies.  Apparently it's used for fly tying, or something like that.

Then, throw away the LED light that comes with the adhesive and replace it with a 405-nm Chinese laser pointer.  These are sold on eBay by the dozen for around US $1 - $3 each, and range from 5x more powerful than they're supposed to be to 20x more powerful.  Unlike the LED, the laser can penetrate some distance into a large blob of the material, making it a good substitute for hot glue.

Pro Tip #2: Wear a good pair of sunglasses when performing Pro Tip #1.

I have a bright 18650 cell flashlight with a Uv LED in it. It has plenty of power behind it, enugh to feel a bit of heat from the light if you shine it on your hand.
Do have some UV glue to go with it, but the resin used for those resin SLA 3D printers works great as glue too, especialy the transparent kind(That also seams to give best results in the printer).

But i still use hot glue quite a bit:
Pro tip: You don't need to wait for a hot glue gun to warm up, you can just take a chunk of hot glue, place it on whatever you are glueing and heat it with a hot air rework station for a few seconds until it looks moten. Once i found out how easy hot glue is to remove with PCB cleaner i just started using it even more.

Pro tip 2: You can also use a hot ait gun to smooth out a hot glue joint into a nice clean looking smooth blob by simply heating it up after it is glued, the surface tension takes care of the rest. I use this a lot for encapsulating connectors on the end of a cable such as 0.1in pin headers, keeps wires from breaking off over time, makes it look smooth and fancy while giving you a good place to grab it when unplging to avoid pulling on the wires.

[tooki]

Used lithium button cells make quick THT LED testers. No current limiting resistor required.

They don’t have to be old. New ones work too!

[retiredfeline]

Used lithium button cells make quick THT LED testers. No current limiting resistor required.

They don’t have to be old. New ones work too!

I think he was just being frugal.

[DrG]

/--/
Pro tip 2: You can also use a hot ait gun to smooth out a hot glue joint into a nice clean looking smooth blob by simply heating it up after it is glued, the surface tension takes care of the rest. I use this a lot for encapsulating connectors on the end of a cable such as 0.1in pin headers, keeps wires from breaking off over time, makes it look smooth and fancy while giving you a good place to grab it when unplging to avoid pulling on the wires.

Thanks for that. Didn't know it and tried it today. Those little two screw terminal blocks do not fit on my breadboards, but they would come in handy if they did. I snipped some jumpers, soldered them on to snipped leads on the terminal block and then "potted" them with hot glue and the hot air gun reflow that you mentioned.

Worked well. The hot glue lends some support, insulation and serves as a spacer so the terminal block fits flush with the breadboard.

[KE5FX]

Please don't do this unless you want to experience what permanent blindness feels like.

Sunglasses are just fine for this application, thanks.  Specular reflections from the beam are uncomfortable to look at, but not particularly hazardous, except possibly to melatonin production.

Blue light is actually pretty safe, optically speaking, because it doesn't focus well at the retina.  The 10x-overpowered 532 nm green pointers from the same vendors are a very different story.  They scare me.

[Berni]

/--/
Pro tip 2: You can also use a hot ait gun to smooth out a hot glue joint into a nice clean looking smooth blob by simply heating it up after it is glued, the surface tension takes care of the rest. I use this a lot for encapsulating connectors on the end of a cable such as 0.1in pin headers, keeps wires from breaking off over time, makes it look smooth and fancy while giving you a good place to grab it when unplging to avoid pulling on the wires.

Thanks for that. Didn't know it and tried it today. Those little two screw terminal blocks do not fit on my breadboards, but they would come in handy if they did. I snipped some jumpers, soldered them on to snipped leads on the terminal block and then "potted" them with hot glue and the hot air gun reflow that you mentioned.

Worked well. The hot glue lends some support, insulation and serves as a spacer so the terminal block fits flush with the breadboard.

No problem.

For that application tho there might be a Pro tip 3:
You can add kapton tape around the thing to make a mold for the hot glue to flow into. As you heat it up with a hot air station it flows out to fill the mold and make a square shape. Same goes if you are potting something with hot glue that has holes that you don't want it to ooze out of (For example some RJ45 connectors need this or the glue will ooze into the conector and ruin it). Regular scotch tape most likely will not handle the temperatures involved, but can sometimes work for just covering small openings.

[Kasper]

/--/
Pro tip 2: You can also use a hot ait gun to smooth out a hot glue joint into a nice clean looking smooth blob by simply heating it up after it is glued, the surface tension takes care of the rest. I use this a lot for encapsulating connectors on the end of a cable such as 0.1in pin headers, keeps wires from breaking off over time, makes it look smooth and fancy while giving you a good place to grab it when unplging to avoid pulling on the wires.

Thanks for that. Didn't know it and tried it today. Those little two screw terminal blocks do not fit on my breadboards, but they would come in handy if they did. I snipped some jumpers, soldered them on to snipped leads on the terminal block and then "potted" them with hot glue and the hot air gun reflow that you mentioned.

Worked well. The hot glue lends some support, insulation and serves as a spacer so the terminal block fits flush with the breadboard.

No problem.

For that application tho there might be a Pro tip 3:
You can add kapton tape around the thing to make a mold for the hot glue to flow into. As you heat it up with a hot air station it flows out to fill the mold and make a square shape. Same goes if you are potting something with hot glue that has holes that you don't want it to ooze out of (For example some RJ45 connectors need this or the glue will ooze into the conector and ruin it). Regular scotch tape most likely will not handle the temperatures involved, but can sometimes work for just covering small openings.

Pumping hot glue into heat shrink works too.

[Cerebus]

Pumping hot glue into heat shrink works too.

Oy! Keep it clean, this is a family friendly forum. 

[Berni]

Oh one more simple one:

PCB cleaner is really good at removing permanent marker marks (The solvent used in permanent markers in generally alcohol based, so no wonder it works so well)

[sandalcandal]

Pro Tip #2: Wear a good pair of sunglasses when performing Pro Tip #1.

Please don't do this unless you want to experience what permanent blindness feels like. You have no idea if and by how much sunglasses reduce the intensity, and with 405nm being visible i don't think that sunglasses will block it. If you are stupid enough to stare at the spot long enough you will probably fry your cornea, and for what? A faster way of curing epoxy that sucks because you can only hit a tiny spot? If you want it to cure faster get a UV lamp... More power, and it isn't nearly as stupid as using a laser.

Btw, you can get decent laser goggles for 60-70 bucks, and with those you know excatly which part of the spectrum they block to what extend. Using sunglasses because they "block light" is just beyond stupid, those things are absolutely NOT designed to handle extremely strong, collimated light.

PS: Rule No.1 of laser safety: If you can see the laser, you done f**ed up.

Sunglasses are required by law to block UV, in Australia at least. Even most untinted safety glasses (with "O" outdoor marking) have UV blocking in Australia. Another option cheaper than laser googles are welding googles/lenses which are good enough for low power lasers due to their need to block intense UV radiation and visible light from welding.

Even the lowest shade 1.2 to only allow 0.0003% 313nm UV but 50% 365nm.  A shade 5 typical for gas welding only allows a maximum transmittance of 0.0003% 313nm and 0.3% 365nm. Outdoor untinted safety glasses are a maximum transmittance of 0.25% >380nm. Some spectrums for US ANSI welding googles here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5000543/

Edit: For reference 0.3% transmittance is an OD of 2.5. The recommended minimum OD For 200mW 380nm continuous is 2.32 = 0.47% transmittance. https://www.lia.org/evaluator/od.php That's shade 10 and over for visible.
Also not trying to say you shouldn't use appropriate safety gear where required but people are often ignoring readily available and adequate options e.g. using welding googles and instead putting themselves at greater risk. Safety needs to be both accessible and adequate.

[KE5FX]

Sunglasses are required by law to block UV, in Australia at least. Even most untinted safety glasses (with "O" outdoor marking) have UV blocking in Australia. Another option cheaper than laser googles are welding googles/lenses which are good enough for low power lasers due to their need to block intense UV radiation and visible light from welding.

Even the lowest shade 1.2 to only allow 0.0003% 313nm UV but 50% 365nm.  A shade 5 typical for gas welding only allows a maximum transmittance of 0.0003% 313nm and 0.3% 365nm. Outdoor untinted safety glasses are a maximum transmittance of 0.25% >380nm. Some spectrums for US ANSI welding googles here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5000543/

Edit: For reference 0.3% transmittance is an OD of 2.5. The recommended minimum OD For 200mW 380nm continuous is 2.32 = 0.47% transmittance. https://www.lia.org/evaluator/od.php That's shade 10 and over for visible.
Also not trying to say you shouldn't use appropriate safety gear where required but people are often ignoring readily available and adequate options e.g. using welding googles and instead putting themselves at greater risk. Safety needs to be both accessible and adequate.

I measured a couple of pairs of sunglasses against the ~405 nm LED that comes with the Bondic adhesive kit.

Reference plot (no attenuation):


Ray Ban 8301:


Serengeti Drivers, sadly no longer sold but probably about 1995 vintage:


Normal polycarbonate eyeglasses for comparison:


The Ray Bans exhibit about 3% transmittance at 405 nm, good enough for use with a blue laser pointer IMO unless you plan to aim it directly at your eyes.  The Serengetis are OK, too.  They have the effect of simulating a pointer that actually meets the rated 5 mW limit. 

Bottom line, if you wouldn't use eye protection with a properly-manufactured and marketed laser pointer -- not saying you shouldn't, but I somehow doubt that many people do -- then you don't need to use anything beyond sunglasses with these overclocked Shenzhen specials.

That being said, I'm not crazy about the lack of IR filtering on these lasers.  The sunglasses do a good job of cutting down on UV and near-UV transmission, but they aren't as effective at 800 nm.  A big chunk of the power output from these pointers is invisible IR, which is arguably more optically-hazardous than the blue light:



Not enough to make me reach for a welding helmet, but it is a bit sobering.

[jogri]

Sunglasses are required by law to block UV, in Australia at least. Even most untinted safety glasses (with "O" outdoor marking) have UV blocking in Australia. Another option cheaper than laser googles are welding googles/lenses which are good enough for low power lasers due to their need to block intense UV radiation and visible light from welding.

The problem is that 405 nm doesn't really count as UV, it is just a deep purple... You really have to look at the wavelength, you can't just assume that just because it says UV it will block a laser (and are we talking about UV-A, B or C?). I'm willing to bet that sunglasses don't provide protection against 405nm, just because that would distort the colours. As you have already mentioned, the transmittance increases quite a bit with the wavelength, if you have 50%@365nm, then what do you have at 405? And let me just quote the product safety page of the australian government regarding UV blocking sunglasses:

The mandatory standard requires that sunglasses must protect users from ultraviolet radiation (UV) within the range of 280 and 400 nanometres.

405 > 400 nm... And 5 nm can make quite the difference for laser goggles as they tend to have rather sharp absorption edges.

But let's tackle the most important reason why both sunglasses and welding goggles are NOT suitable for lasers: LASERS EMIT COHERENT LIGHT
Both the sun and the arc from a welder won't do that and thus won't even come near the obscene photon/energy densities of a "small" 100-500 mW laser. Combine that with the fact that blue (and probably 405nm) light is by far the most dangerous wavelength for your eyes as it will instantly boil the blood in your retina -> not great. Just to really pronounce the difference between a laser and a "normal lightsource": If i project the full output of my 300 W 30 mm mrad laser at a wall 10m away i will get a spot with a power density of 240 kW/m^2. If i switch on a 300 W lightbulb i will get 1 W/m^2... Same power, yet the laser provides a spot with 10^5 times the power density. The intensity of non-coherent sources correlate with the distance cubed, but lasers don't follow that rule... In that example, the 40mm spot from 10m away just becomes a 130mm spot at 100m.

Blue 445 and 405 nm are just on the edge where the lens of the eye is transparent and where light will get focused on the retina-> tiny spot (the diameter is in the um range as the incoming light is coherent [nature never expected such light in the first place]) with extreme energy density that can already be in the kW/cm^2 range with a 5mW laser.
UV-A to C (380-100 nm) get blocked by the lens, so they don't get focused and can dispense their energy over a wider area (still NOT recommended) as exposure will lead to cataracts.

So should you use welding goggles or sunglasses that where never designed to block neither coherent light nor light over 400 nm to look at a 405 nm laser? Absolutely effing not.

The Ray Bans exhibit about 3% transmittance at 405 nm, good enough for use with a blue laser pointer IMO unless you plan to aim it directly at your eyes.  The Serengetis are OK, too.  They have the effect

That's a OD rating of 1.something... Aka: A joke, especially with unknown 100+ mW diodes. You really shouldn't go below 4 or 5.


(Sorry for the rant, but saying that it is safe to look at a laser with anything other than proper laser goggles just doesn't sit well with me)

[KE5FX]

That's a OD rating of 1.something... Aka: A joke, especially with unknown 100+ mW diodes. You really shouldn't go below 4 or 5.

How is it a joke?  The data shows that sunglasses have the effect of attenuating the overpowered laser pointer output to levels that international regulatory agencies have deemed acceptable for use without specialized eye protection. Your argument is evidently with those agencies, not with me.

If there's a villain here, it's the shady Chinese vendors who are selling hazardous items for $3 each on eBay.  I can measure the power and spectral output from these lasers and treat them accordingly, but most of their customers can't or won't do that.  I'm not complaining -- hey, cheap lasers are cool! -- but I wouldn't be surprised if governments step in at some point and ruin the fun.

(Sorry for the rant, but saying that it is safe to look at a laser with anything other than proper laser goggles just doesn't sit well with me)

I hear you, but the fact is, there are just not a lot of people walking around with eye damage from indirect viewing of laser pointer output without $100 goggles.  Either everyone else is a reckless moron, or you're overly risk-averse.

(Although, to be honest, the more I think about that IR line, the more I'm tempted to swap out the RayBans for my Thor Labs safety glasses that make everything look like it's being viewed through the atmosphere of Venus. They are rated OD 4 at 808 nm, no problem there.)

[richard.cs]

But let's tackle the most important reason why both sunglasses and welding goggles are NOT suitable for lasers: LASERS EMIT COHERENT LIGHT
...
That's a OD rating of 1.something... Aka: A joke, especially with unknown 100+ mW diodes. You really shouldn't go below 4 or 5.

I am fairly sure the darker arc welding lenses would be "safe". A shade 14 has a visible-band transmission of at most 0.0012%, so min OD 4.9 which is probably OK, but note that it is not nearly so attenuating in infrared (assuming those are percentages in that column it's OD 2.5). The doubling lasers without IR filters are scary.
https://qph.fs.quoracdn.net/main-qimg-63d2b2785a54da76ef6f8efae0ba72e6-c
It's still a crap idea, welding goggles this dark are as good as a blindfold unless you are outdoors in full sunlight.

(Sorry for the rant, but saying that it is safe to look at a laser with anything other than proper laser goggles just doesn't sit well with me)

I am inclined to agree.

I hear you, but the fact is, there are just not a lot of people walking around with eye damage from indirect viewing of laser pointer output without $100 goggles.  Either everyone else is a reckless moron, or you're overly risk-averse.

Of course you unlike many people seem to have the ability to measure the OD of your pair of sunglasses. Saying "I've measured these specific sunglasses and I am comfortable with their attenuation" is very different from other people pulling a random pair out of the drawer and trusting them.

[sandalcandal]

405 > 400 nm... And 5 nm can make quite the difference for laser goggles as they tend to have rather sharp absorption edges.

But let's tackle the most important reason why both sunglasses and welding goggles are NOT suitable for lasers: LASERS EMIT COHERENT LIGHT

The suggestion is the possibility of using broadband protection with safety glasses and welding goggles for general radiation protection so sharp transmittance edges on laser goggles is irrelevant.
The required OD 2.32 at the end of my post is using a laser protection guideline so it is considering coherent light specifically at 405nm CW and the shade 10 is 2.64 OD over visible and 2.80 OD above 365nm. 2.64 OD at x wavelength is 2.64 OD at x wavelength regardless if sharp transmittance materials are used.

I appreciate your concerns though. Laser safety goggles are the go for laser safety. Particularly for anything substantial (Class 3B). I've done research in photonics labs with class 4 lasers as a student.

[DrG]

Drill a small hole in a Ping-Pong ball to make a good LED light diffuser.

[jogri]

How is it a joke?  The data shows that sunglasses have the effect of attenuating the overpowered laser pointer output to levels that international regulatory agencies have deemed acceptable for use without specialized eye protection. Your argument is evidently with those agencies, not with me.

Where did you get those facts? Do you mean that it is eye safe because the output is less than 5 mW when it reaches the eye? that number is only valid for IR filtered 532nm green lasers, a 5 mW 405 is a class 3 laser... You can't just assume that just because the output is lower than x mW it has to be safe... The rating heavily depends on the wavelength:

I hear you, but the fact is, there are just not a lot of people walking around with eye damage from indirect viewing of laser pointer output without $100 goggles.  Either everyone else is a reckless moron, or you're overly risk-averse.

(Although, to be honest, the more I think about that IR line, the more I'm tempted to swap out the RayBans for my Thor Labs safety glasses that make everything look like it's being viewed through the atmosphere of Venus. They are rated OD 4 at 808 nm, no problem there.)

How do you know that? I know a couple of guys with permanent eye damage from a laser, the damage also depends on the wavelength... It can either fry your lens or retina, the guys i know screwed around with 500 mW lasers and got a couple of dark spots in their vision. You only notice that sort of thing when you are staring at a white paper.

And what IR line (your post has no pics)? A 405 nm diode laser shouldn't have a 808 nm line, those kind of diodes are only used in green laser pointers to excite the NdYAG crystal that emit at 1064.

[Cerebus]

On cleaning permanent marker off of things.

Alcohol usually does the trick, but sometimes there will still be a residual shadow left after the bulk of the ink is gone. I've successfully removed the shadows, without any apparent damage to the surface, by using a melamine sponge (sometimes sold as 'magic eraser' sponges or under a very similar name) with a little alcohol.

I've done this on second hand test equipment, that had asset numbers or department names in permanent marker, and I couldn't tell you now where the markings were from examining the kit as it is now.

[Sorry, I realise this has nothing to do with quibbling about 'laser' safety.]

[Ranayna]

Not so much electronics, but Fran's little trick for re-seating self-tapping screws by starting in reverse first until it finds the groove. So simple, yet effective.

At some point this became intuitive for me. I dont know if someone showed this to me or if i figured it out myself. But i remember several messes i made with self tappers in cheap plastic 
For similar reasons i also try to organise unscrewed self tappers in a way to be able to put them back into the same hole they came from. Especially cheap screws are so inconsistent that even if you hit the groove, you still do damage with another screw.

[Cerebus]

A suggestion.

I was pleased to see this topic. A discussion that gradually gathered a collection of 'tips and tricks' sounded like an excellent thing. I could see how it might, in time to come, form the basis of a very useful repository of knowledge.

It seems to have been taken over for yet another disputation between the 'safety zealots' and the 'safety libertines'. I wonder if the members of both groups would consider:

1) Starting a new topic to debate the safety issues in, and having done so, taking that discussion there.
2) Once they have done that, deleting their own contributions on the subject from this topic to preserve its nature as a helpful repository.

Thank you for your consideration.

[richard.cs]

Alcohol usually does the trick, but sometimes there will still be a residual shadow left after the bulk of the ink is gone. I've successfully removed the shadows, without any apparent damage to the surface, by using a melamine sponge (sometimes sold as 'magic eraser' sponges or under a very similar name) with a little alcohol.

I am familiar with the residual shadow problem, but not the 'magic eraser' - I shall have to try it.

Not so much electronics, but Fran's little trick for re-seating self-tapping screws by starting in reverse first until it finds the groove. So simple, yet effective.

At some point this became intuitive for me. I dont know if someone showed this to me or if i figured it out myself.

Same, I do this, but I can't remember when I started. And not just on self tappers either, any awkward screw that "wants" to cross-thread.

[DrG]

There may be a few people who still don't know this one

Use your digital camera (night setting if you have it), to see if your IR LED (remotes etc...) is working.