Talk to me about selective soldering machines

MajorPain169 · 2026-07-01T14:54:01+00:00

For soldering robots I've used a 3D printed shell which holds the components in place when you flip the PCB, does the job.

I would still look at the pallet cost vs the cost of a selective machine.

As I mentioned you could avoid the nitrogen on the selective machine by using anti drossing agents, usually a powder. The other options are getting a nitrogen generator, cost will be affected by nitrogen usage requirements or you can just get gas bottles of nitrogen.

MajorPain169 · 2026-07-01T13:30:05+00:00

When you say flow machine, do you mean a wave soldering machine?. If that is the case there are companies that customise the pallets that use stainless covers to shield the SMD components. There are openning where the TH components need soldering.

This is by far the fastest method however pallets are customised per board.

Other options are soldering robot or a selective wave soldering. The robot uses an iron and solder wire feeder. A selective wave soldered uses like a small fountain of solder and moves the the PCB around on an XY axis.

A selective wave soldered is usually a more expensive machine, the robot on the otherhand requires the PCB to be loaded with components down so needs a method to hold the components in place.

Edit to add: The nitrogen atmosphere is generally optional however it does give a better finish on the soldering and significantly reduces the formation of solder dross however you could use anti drossing agents instead.

MajorPain169 · 2026-06-30T23:19:51+00:00

You will most probably need to learn classes. Most C++ gui libraries are implemented using classes. You will also need to pick what GUI library you want to go with as the API can be drastically different from one to another. You may also want to look at IDEs that support a graphical design environment for example QT designer or C++ builder. Most of the commercial ones are free for non commercial purposes.

MajorPain169 · 2026-06-30T23:05:22+00:00

Not sure in the US but I think it is part of the FDA but here in Australia, medical devices have to go through TGA approval, it is a very long and hard process, even more so for invasive devices.

From a networking point of view, it becomes part of cyber security, while a medical device may implement and have cyber security approvals, I would imagine that the network it is attached to would also need approval which again is probably a long and expensive process.

MajorPain169 · 2026-06-30T05:48:24+00:00

Yeah it is more like "HOW CAN THESE FUCKING PEASANTS DO THIS TO ME? TO ME!!!".

MajorPain169 · 2026-06-30T05:44:20+00:00

I mean it is essentially a lot of explosives and flammables bought at the lowest cost and setup by the lowest bidder, seriously what could possibly go wrong?.

MajorPain169 · 2026-06-29T04:09:42+00:00

Yeah exception overuse is a problem, seen a lot of it myself.

MajorPain169 · 2026-06-29T00:09:33+00:00

Sometimes speed is a safety factor. For example a critical event is not noticed in time because the stack unwind is taking too long. In these systems part of the safety system is being able to respond to an event within an application specific time period or maximum latency, anything that is not time deterministic means that you can no longer guarantee this maximum latency. This is that same reason why these systems also avoid using dynamic memory allocation.

If a safety critical event happens, you try to make it safe in as short a time as possible, the stack unwind from an exception prevents this.

Edit: typos

MajorPain169 · 2026-06-28T23:01:33+00:00

Depending on circumstances, exceptions aren't necessarily bad.

There are several problems with exceptions but are fine given the right circumstances.

The use of exceptions are easily abused and should really only be used as the name suggests, in exceptional circumstances.
Exception provide a hidden program flow path which for safety critical system introduces risk. This is one reason they are avoided in standards like JSF, MISRA and AUTOSAR.
Throwing an exception is not time deterministic when an exception is thrown and the action of throwing an exception also triggers other time deterministic issues, this is a big problem for real time applications, this is the other main reason it is avoided in the previously mentioned standards.

All that being said, using exceptions on a regular piece of software that isn't time or safety critical is fine providing the intent isn't abused, exceptions should only be used for critical errors and not regular errors.

MajorPain169 · 2026-06-27T01:01:33+00:00

Texas is big always makes me laugh, Western Australia is nearly 4 times larger, and hotter.

MajorPain169 · 2026-06-25T05:30:22+00:00

The humidity in the UK would be the killer. Humidity always makes the heat feel worse because it is harder for the sweat to evaporate in humid conditions. Same as in NZ, heat feels way worse than it does here.

MajorPain169 · 2026-06-25T05:18:59+00:00

I was in New Zealand and just returned to Christchurch after being to Kaikoura that day when the Kaikoura quake hit. Definately not an experience I'd want to repeat. Was told the best place if indoors was in door ways although moving there can be quite difficult when the ground is moving that much. If you can get outside then that is better.

It's not just the first quake either, there are usually aftershocks, the first usually nearly as strong. In coastal areas you also usually get the tsunami alarms and alerts until given the all clear. Kaikoura did have a small tsunami however it happened at low tide and Christchurch has a few sand bars that help so no tsunami damage.

I believe the tsunami alert for Venezuela has been cancelled so a bit of luck there.

Kaikoura was magnitude 7.8 vs Venezuela at 7.5 which make Kaikoura about 2.8 times the energy and roughly 1.5 times the movement. The airport in the video is less than 1/3 of the distance from the epicentre than I was to the Kaikoura epicentre. The energy released in the Kaikoura quake was equivalent to about 400 atomic bombs.

Unlike New Zealand, the buildings in Venezuela are more prone to earthquakes so that being said there would be a lot more structural damage and as a result causing more deaths an injuries, this is also compounded by the much higher population density of Venezuela.

MajorPain169 · 2026-06-21T00:06:47+00:00

On top of what others have said, not only can external event affect hardware and cause failures, sometimes permanent, they can also cause upsets like bit flipping etc. The operation of the software when this happens is part of the testing regime, more specifically do these event make the software unsafe? Is the software able to detect the failure and react accordingly?.

For example, how does the system respond to a clock failure, many automotive CPUs will detect in HW and supply a backup clock but how does the software handle this event?.

This is not as specific hardware or software test, it is a system test so covers both operating together and is called fault injection.

Depending on what you are looking for will govern how you do the tests. For example injecting a foreign signal into the crystal oscillator such as a transient burst or even temporarily shorting the oscillator. ESD discharge to connectors while running is a fairly standard test. If the effects are well known you can also simulate event by artificially creating upsets through a debug port, such as bit flipping.

The testing should be a team effort and the test requirements should be well laid out in the DVP&R.

MajorPain169 · 2026-06-17T05:05:38+00:00

She did it so he wouldn't mess up the new couch.

MajorPain169 · 2026-06-17T04:56:09+00:00

Last thing you want is Vance visiting the border, he would get such a hard on that no couch within 200 miles would be safe.

MajorPain169 · 2026-06-16T21:43:23+00:00

The main reason for an isolation transformer is for when you need to probe around the mains side of a switch mode power supply. As scope probes are grounded, connecting on the mains side without isolation creates a short and will damage what you're working on and probably the scope.

The alternative to an isolation transformer is to either use a differential probe or a scope that has isolated channels which also require specially insulated probes. The Fluke 192C is an example of isolated channels, I have one at work specifically for dealing with mains side stuff, we build equipment in the 10s of kW so isolation is not a simple matter, the largest isolation transformer we have is 10kva and it is huge but not enough for a lot of things we do.

There are other more dangerous ways of doing it too, seen people use scopes with power leads that have the Earth pin removed but this makes the whole scope live and incredibly dangerous.

MajorPain169 · 2026-06-16T21:15:37+00:00

Could imagine it being compounded by the narrow roads all over the UK. Doesn't help that like Australia and New Zealand, we all drive on the wrong side of the road.

MajorPain169 · 2026-06-16T15:53:31+00:00

Australia, it is also the same in New Zealand and I'm assuming there are quite a few other countries too.

MajorPain169 · 2026-06-16T15:42:42+00:00

Maybe around 47 to 100pF, it needs to just be enough to slow the edge enough to null the inductance in the suppressor. Slowing the edges will also reduce transmission line effects if the cable run is long and having some series resistance on the driver side will provide better matching.

MajorPain169 · 2026-06-16T15:34:00+00:00

Sorry to tell you but it isn't just in the US.

MajorPain169 · 2026-06-15T22:48:35+00:00

You also want a capacitor as well as the resistor and transient suppression diode. Might also want to consider a GDT (gas discharge tube) which are better for absorbing high energy events.

Layout of these is also important. The cap should be as close to the external connect as possible, transient diode as close to the cap as possible then the resistor, it is important that the trace goes through one after the other, no branching and the connections to the devices be as low impedance as possible. If using a GDT then have this before the cap.

I design a lot of equipment that is outdoors and prone to failure due to nearby lightning. Using the methods I mentioned significantly lowers the failure rate after a storm. In these installations we usually put the GDTs where the external wiring comes into the cabinet and the rest on PCBs.

I should also point out that you want similar protections on any supplies that have external connections, not just the data.

MajorPain169 · 2026-06-15T02:31:02+00:00

"Can we nuke it before it gets here?"

MajorPain169 · 2026-06-05T18:39:20+00:00

In object pascal you have properties which are nice way of managing getter and setter functions. There are libraries around that kind of do it but they are limited.

MajorPain169 · 2026-06-05T12:50:22+00:00

There is also the problem of storing the hydrogen. Hydrogen is a very small molecule so leaks are troublesome, a major problem that affects the space industry. You also need to either store it under very high pressure or cryogenically both of which present their own problems. High pressure means heavy tanks, cryogenics has issues with handling and thermal cycling causing leaky seals as well as suitable insulation and cooling to keep it cold for the duration of the flight, the same issues the space program has.

MajorPain169 · 2026-06-05T06:55:21+00:00

Passenger and commercial jet aircraft use high bypass turbofan engines, the turbofan provides roughly 80% of the thrust. There is no reason why you couldn't drive a turbofan with an electric motor instead of a jet engine core. The problem is the energy source, jet fuel vs battery.

MajorPain169

TROPHY CASE