The times when hydraulic systems were purely hydraulic are long past now, and modern hydraulics and electronics are inseparable, which is why every respectable hydraulic technician should know at least basics electronics and industrial automation if he or she wants to succeed in this profession.
Standard industrial solutions are well known and explored. Every respectable hydraulic firm chooses a couple of known brands (Schneider Electric, Siemens, etc...) and the respective tools and tends to stick with them for all emerging electric control and automation needs, both complex and simple.
There is nothing wrong with this approach, but I am sure that a lot of engineers and technicians who fancy DIY electronics (and it is no secret that most people who choose mechanics and its variations for a profession, like oil hydraulics and mechanical engineering, are makers at heart) often come across automation or control problems that can be solved with means much simpler than PLC based or other standard industrial-component-based solutions.
Like, for example, when you have to channel a proportional signal from a joystick to several actuators based on simple binary logic (the pin is out - enable rotation, the pin is in - inhibit rotation, or the button is pressed - the joystick controls function "A", the button is depressed - function "B").
An industrial engineer envisions a standard electric cabinet with rail mounted components inside, or a PLC with several analog inputs, or something else...) but a maker inside him looks at the task in hand and says something like "Dude, a couple of solid-state switches and a 30 cent binary to decimal decoder can do all this!". And then the maker thinks about how many dozens of ICs he could buy with the price of a single cheapest PLC...
For a long time, I thought that, yes - making is fun and all, but there's no place for DIY hand-made electronics in industrial projects. DIY is for your garage, and it is good to make that flushing light bulb or something that will look extremely makeshift and maybe once in a while you will show it to your friends who will say "Yeah... this looks nice! It almost looks like a real deal!" And then they will pat you on your shoulder and think to themselves: "This guy clearly has too much free time on his hands..."
Nowadays, however, things are different. Modern "DIY electronics" has nothing to do with what it used to be even 10 years ago, and here are a few key improvements:
I guess in this day and age this can be said about everything. The internet has made tons of information and tutorials on DIY electronics available to everybody. So you don't learn electronics only if you don't want to.
Programs like EasyEDA or the KiCad (which I use all the time) lift the design process to a professional level. Free of charge! And - to top it off - there are tons of free tutorials online, so you don't need to draw your designs "on a napkin" anymore, and any DIY project gets the ability to be professionally documented.
Modern components and suppliers.
Due to companies like Mouser, Digikey or TME (Europe) and others, it's never been easier to source electronic parts. When I was tinkering with electronics as a kid - getting parts was a lot trickier. I would have to spend a whole day hunting for parts on the electronic components flea market. Also - modern SMD stuff is much smaller and much tougher than the through-hole components I used back in the day. It's only going to get better.
JLCPCB, PCBWAY, PCBGO and many others (these three are the ones that I tried personally, and I can say that I was satisfied with the results that I got) will make you 5-10 professional looking PCBs for just a few bucks. I still remember etching my own PCBs at home...
The same places that sell you components will also offer a selection of enclosures for your project. So, not only your design will be soldered on a professional-looking PCB, but you will also serve it in a professionally looking "package".
Properly selected SMD components can be easily soldered by hand with a quality soldering iron, hot plate, and a hot air station - all of which can be sourced very easily, and is not that big an investment if you choose wisely. You would not believe how much you can do with a TS100 iron (60 bucks for the iron plus another 20 or a couple of tips), an 858D hot air station ($30), and an electric skillet ($30)...
All right, you say, this stuff is great! But even if a hand-soldered PCP in a nice IP67 enclosure can have a professional look, what are the advantages of going the DIY route? Isn't it just too much fuss for nothing? Well - here's a few for you:
Cheap and compact.
You can assemble a much cheaper and much more compact solution in comparison to standard industrial rail-mounted components. This is especially true for small projects. In fact - I am defending the opinion that choosing this solution only makes sense for relatively simple tasks. Of course, what's "relatively simple" for you is only defined by your expertise and the level of your skill.
Just imagine a PCB with your company logo displayed in the silkscreen. Instant success! Are you guys manufacturing electronics now? Wow!!
By the way - most of the times you can by-pass the fact that "unique solution" equals "no spare parts" by ordering (and factoring in your quote) twice as many parts (for PCBs it is usually a given since minimum order quantities start at 5 to 10 units). Very often the low cost of components will allow it. Now try doing that with industrial relays that come at 50 bucks a pop!
Useful skill and lots of fun.
When you embark on such a project - you are polishing a useful skill and, in general, such projects are a lot of fun. That is - if you are into making!
And, of course, I should mention the other side of the coin:
Skill is indeed needed.
The only way to get there is through practice. A lot of practice. And a lot of mistakes. So DIY electronics in industrial projects can only be applied by those who know what they are doing. There's a silver lining though because if making is your hobby, the learning process is more fun than hard work.
So, modern electronic DIY has come such a long way, that with a proper skill - the use of hand-mounted SMD-component-based projects has become a viable solution for certain industrial automation and control demands.
And to conclude - here's a list of what I can recommend, should you ever decide to go the DIY way:
* Always buy more components than you need. You never know when you accidentally burn something. Ideally, you factor in your quote twice as many parts as you need.
* Always oversize your components' voltage and current rating. If you work with hydraulics - you are already used to it.
* The same goes for the PCB design - the wider a track is the better! (Within reason).
* Always include input, reverse polarity protection, high current protection, and transient voltage protection. Especially for mobile. (A simple diode is a good place to start).
* Now - the biggest advice of all. Always document everything, and make a nice file with user instructions. This is the one step you can't skip. Not for something that you sell for money. Things break, operators change, notes get lost - industrial projects are to last. Never forget about it.
From my personal experience - this "risky business" (example) takes some time and effort to master, but like any investment in knowledge, which I believe it is, it pays off.
The more tools you have and know how to use - the better!