Hi.
I sent a PM to @crutschow asking about his footnote that says "KISS is my design goal". As he didn't respond me, I summon him here to answer publicly, maybe that's the thing, he doesn't like talking in PMs.
What is "KISS" supposed to mean? The band? The rest of your footnote talks about electronics, so I guess it's another mention to electronics, but I never heard about it.
Can you clear that out for me/us?

 

Hi.
I sent a PM to @crutschow asking about his footnote that says "KISS is my design goal". As he didn't respond me, I summon him here to answer publicly, maybe that's the thing, he doesn't like talking in PMs.
What is "KISS" supposed to mean? The band? The rest of your footnote talks about electronics, so I guess it's another mention to electronics, but I never heard about it.
Can you clear that out for me/us?

Keep It Simple Stupid.

 

In plain English, there will always be more than a single solution for a given problem. Some will be simple, some will be complex. The "KISS principle" dictates that you should select one of the simple ones.

 

What is "KISS" supposed to mean?

It's an acronym for Keep It Simple Stupid.

https://www.bing.com/ck/a?!&&p=71e5...53aWtpcGVkaWEub3JnL3dpa2kvS0lTU19wcmluY2lwbGU

 

Thank you, everyone.
I didn't google it because it was missing one word for me to understand I could search about it: principle.
I couldn't think other than the band LMAO.

 

If your audience is too easily offended (which is increasingly the case, these days), then the alternative is "Keep it Sweet and Simple".

The example that comes to my mind of the KISS principle being applied in the extreme, were the wing root switching valves on the F-15.

The idea was to reduce vulnerability of the hydraulic systems to combat damage. In a typical fighter aircraft of the time, you had three hydraulic systems, FC-1, FC-2 and Utility. The FC systems (Flight Control) powered the primary flight control surfaces with each of them powering the surfaces on one side of the plane, while the utility powered everything else, including the flaps. To provide back-up power to the flight controls, one of the other two systems would also go to the actuator, with a check valve to allow the backup to take over if the primary was lost. This resulted in a lot of hydraulic lines going out into each wing, making if much more likely that a single shell coming though the wing (or other damage-inducing event) would compromise multiple lines. Plus, if the actuator itself was damaged, it could cause the completely loss of both hydraulic systems connected to it.

So with the F-15 they sent out a single pair of lines (pressure and return) into the wing and tapped off it for the flaps and aileron. To provide backup, they have a switching valve at the wing root that has one of the FC lines (called PC -- power control -- on the F-15) and the utility going to it. The switching valve normally sends PC power into the wing, but if PC pressure is lost, it has to test the integrity of the lines in the wing to determine if they caused the loss of the PC system, in which case you don't want to send utility pressure out there because you'll just lose it, too. It does this by sending backup pressure out into both the pressure and return lines in the wing to see if they both hold pressure, but through a small orifice such that, if the lines are severed, it only results in a slow leak. If pressure builds up adequately, then full-flow utility is provided.

So, that's what it does. It's how it does it that is the epitome of KISS. The first versions of it (ground development, I don't think these ever flew) had all kinds of pressure sensors and some electronics to control various valves to make this happen. But now you have concerns about what happens if electrical power is lost (after all, this is for dealing with combat damage). So they made it so that things were all mechanical, with linkages moving valve pistons in response to things. They kept working at it until they ended up with a completely self-contained unit that fits in the palm of your hand and that is nothing more than a block of aluminum with three holes bored in it and drilled passageways connecting them to the ports. Within each hole a piston (called a spool) moves back and forth under the influence of the internal pressure differences. The three spools, which are nothing more than precision-machined cylinders with grooves turned into them, are the only moving parts. Not even any springs involved. Under normal operations, the spools are held in place by the difference in pressure between the primary pressure line and its return line. If primary pressure is lost, the backup pressure moves one of the spools to the other side, which routes pressure from the backup to move one of the other spools so that it cuts off the primary source and connects the backup pressure to both the pressure and return lines going out into the wing, but through controlled leakage around the spool. This combined pressure is used to move the third spool to connect the backup pressure/return lines out to the wing. But that can only happen if pressure can build up enough to move it, since pressure from the back up source is pushing it the other direction to keep it closed. If it can't switch, the backup system continues to drip fluid into the wing at a couple drops a second. The entire process takes about two to three seconds.

Every time I overhauled one of them (which was very simple, it was a matter of carefully removing the spools, cleaning everything, putting it back together with new end seals, and testing it -- we never had one fail test, either), I would just look at it in amazement of how such extreme engineering could produce something that was so elegant and simple.

 

My meaning for the KISS acronym is dl324's in post #4.
It goes along with Einstein's dictum "Everything should be made as simple as possible, but not simpler."

 

Another polite meaning would be "Keep it Short and Simple".

 

Lets face it, adding unnecessary complexity IS stupid.

 

The fewer parts you use to do the exact same thing the fewer there are to fail... Or, Don't over-engineer. You don't need an atomic clock to tell you when it's teatime...

 

My biological clock is far more accurate than any atomic clock when it is time for coffee.

 

Lets face it, adding unnecessary complexity IS stupid.

More or less.
But it's common for newbie designers on this forum to make a circuit a lot more complex then necessary due to lack of design experience.

 

To be fair, the KISS principle is also often misapplied and solutions that really are too simple to be truly adequate are accepted and bad things can and do happen as a result.

 

To be fair, the KISS principle is also often misapplied and solutions that really are too simple to be truly adequate are accepted and bad things can and do happen as a result.

So we just need to find the right amount of "Goldilocks" simple.

 

So we just need to find the right amount of "Goldilocks" simple.

Yep, and when you think about it, that's what a true engineer's job really comes down to -- not just solving other people's problems, but finding an appropriate solution to their problem.

 

Yep, and when you think about it, that's what a true engineer's job really comes down to -- not just solving other people's problems, but finding an appropriate solution to their problem.

One of the most important lessons I learned in my professional career was to always first figure out what the end result was that the customer expected.

A lot of times I fell into the trap of following the customer's lead and waste a lot of time in the process instead of me leading them to an optimal solution.

 

One of the most important lessons I learned in my professional career was to always first figure out what the end result was that the customer expected.

A lot of times I fell into the trap of following the customer's lead and waste a lot of time in the process instead of me leading them to an optimal solution.

The first step in the engineering problem solving process is to understand what the problem is -- and it is also frequently the hardest step in the process. It is not at all uncommon to be dealing with a customer that thinks they know how to solve the problem and just want you to implement their solution, when in reality, they don't really understand what the problem is that actually needs to be solved and, in fact, are sometimes not even close. Depending on the customer, that can either be some of the most rewarding experiences as you educate each other to tease out the real problem and what would constitute an acceptable solution, or it can be some of the most frustrating and aggravating experiences as they insist that they know everything you need to know and refuse to give you critical information because they are scared you will steal their idea. Fortunately, I had a lot more of the former and only a couple of the latter.