1st Year Tafe Rant - Electrical and Communications - Page 1
Forum section: electronics / general

author: TravisD
author_rank: Newbie
timestamp: November 14, 2016, 12:28:34 pm
content: Hello everyone, First I'll start off introducing myselfMy Name is Travis 24I have been playing around with electronics for quite a few years now and currently employed as a Radio Frequency Technician Apprentice/ Bench Technician working for a Radio Communications company/ repair agent for GME and several radio brands.I know this is only just a Tafe coarse and I am not trying to be mean towards the Tafe or my Teachers and I am only sharing my view.I am down in Brisbane undertaking Tafe training for my 1st year in Electronics and Communications.I well knew I was going to pass this course in flying colours as I have lived and breathed this stuff since I was young and knew what I was in for this year at Tafe since everyone else at the company has already done completed the 4 years with satisfactory marks without even having knowledge of the basics like Ohms law. (they're more labour type guys. Climbing towers and stuff)So I completed a whole two weeks of the six at Tafe and to be honest I haven't ever cringed so hard before in my life on what we're being taught...We no joke did a whole week doing resistor colour codes and resistor series circuits. the whole class of 8 guys are falling asleep by this point.2nd week, now that is over our first project is to make a Linear PSU using the LM78** and LM79** seriesSure easy enough to design and make. oh wait.. check out that schematic and PCB already supplied for us (See images attached)I have designed several boards before and I noticed many things wrong with this. Can You?Notice the floating ground pour? its not even neg but FLOATING sure this ins't too bad as its not much of an issue here but all the components are all over the shop and the complete wrong pitch for every component except the T0-220 packages on the regulators so I asked the teacher who designed this PCB and he told me its all auto-routed! This explains it!WHY I asked, He then asked If I flew to Brisbane or drove a car? I responded "flew" and he replied "see you take the easy route to get better result, computer do all the work like airplane"... I just...Ummmm what? I couldn't even.This does explain a lot I guess about the PCB but what about that Schematic? Are you trying to make this hard to read? (see images)Sure okay I'll work with this board but i'm not happy with it.So do we get to solder yet?no. lets first learn how to make a chair in AutoCAD since its not something no on the test.. No joke 2 hours wasted watching my teacher figure out the program and extrude 3 squares.Okay soldering time!"Before you can solder you have to work on test boards"sure okay fair enough, some people haven't soldered before and this is a good idea. So we have to desolder the last year students board and clean it up and reuse it.. now we have to form the leads of the resistor for the pitch of the test PCB but wait... We have to do methods of stress relief by adding fancy loops or silly methods causing more work for us but as explained by our teacher "if you dont do this the legs of the component will snap when the solder dries". So here we are added loops to each resistor making sure they're all in line and right height and such, has to be perfect (pictured board isn't mine). I add my resistors into the PCB and go to start soldering when the teacher stops me and tells me I am doing to wrong as my leads are bent outwards (to hold the resistor in place) and how this will make the solder flow sideways and wont work as it needs to be straight? umm okay so I straigten them all up and use masking tape as recommended and complete all the loops and bends and solder the entire board and takes no joke like 3 days just to find out we have to do it all again on our own TEST BOARD! RAGE!!! but hey, practice makes perfect right?Have you ever seen this method or stress relief performed on components before? also in order to get true 90deg bends he told us to pull tight the legs.. wouldn't this cause more stress then the contraction of heat? I'm actually asking!So we spend 2 more days on this test board to then be presented with an exam board. yep another board EXCEPT it also has DIP packages!except everything is the wrong pitch AGAIN! not only are we doing thought-hole DIP but also SMD DIP? yep! so we're made to force out the legs of the IC to make them fit the board and pads. "this is correct" the teacher insures us. I asked if we had some Flux and he said use some isoproyl alcohol? what? By this time I'm pretty fed up with the whole thing and just want to start on the PSU already and go home.Check out my teachers soldering skills on the PCB and I have so many problems with this design etc. He's confident the 12v and 5v rail can supply 1A without problems. ummm yeah I expect fire.. our heatsink is just a bar of aluminium and they're isn't a single air source in the PSU box we've made. its practically sealed! also why dont we move all the LM78** regs onto the heatsink and the LM79** to its own heatsink instead of it being the LM7809 all alone with its own heatsink? (sorry I didn't supply the component layout) then we wouldn't have to insulate the Bar heatsink as it wouldn't conflict with the pinouts of the 7912 reg... just saying?I know I have a lot of things I can add to this but its getting late and Im pretty tiredTafe is what you'd expect I guess. I am having fun in the end and the guys are learning quite a bit being here so its not all badWow that was a big rant... but yeah I have 2 weeks of stuff to talk about. I'm most likely going to keep adding stuff to this as my time at tafe goes on.Remember I'm just having a rant and have nothing against the Tafe or my Teachers and I'm only just posting for giggles.</rant>

author: ovnr
author_rank: Frequent Contributor
timestamp: November 14, 2016, 12:57:18 pm
content: Eh, expecting education to not be terrible was your first mistake.Also, schematic was done in Multisim and thus I'd be shocked if the board wasn't made in Ultiboard; if so, that's not auto-routed, because the Ultiboard autorouter is much shittier than that.The strain relief loops are a thing, but not really done very often.

author: snarkysparky
author_rank: Frequent Contributor
timestamp: November 14, 2016, 01:05:13 pm
content: Why does multisim draw such crappy schematics. It's the worst user interface imaginable. They should take a look at LTSpice for how its done.

author: madires
author_rank: Super Contributor
timestamp: November 14, 2016, 01:40:39 pm
content: Bending leads outwards makes manual soldering easier, but it's not done usually. When you repair stuff, you'll understand why. For some applications, like avionics or space, bent leads might be required. There are some interesting videos on youtube about this topic.

author: dmills
author_rank: Super Contributor
timestamp: November 14, 2016, 03:42:40 pm
content: The loops for strain relief are a thing in IIRC one of the MIL or NASA PCB assembly standards.You don't see it often, but there is nothing inherently wrong with teaching it.As a soldering practise board I see nothing wrong with that cascade of regulators, it will be easy to Go/NoGo test as part of marking.Yea it is not what a working engineer would design, but that is not really the point.

author: vk6zgo
author_rank: Super Contributor
timestamp: November 14, 2016, 03:43:07 pm
content: The idea of the looped component leads is for heat dissipation,& for some degree of strain relief on larger components---it has nothing to do with the leads "snapping when the solder dries",Can you think of some problems such loops would cause?---Think HF!I think TAFE is pretty much beyond repair----the idea that Techs might actually learn about Electronics in these courses seems to be totally foreign to their thinking.The intention is apparently to produce people with a limited number of "monkey see,monkey do" abilities.as we are told Industry requires.I have run into people with a "Certificate 2 in Electronics" to whom Ohm's Law is a new & startling concept!

author: TravisD
author_rank: Newbie
timestamp: November 14, 2016, 08:06:45 pm
content: Thanks guys for clearing up a bit about the stress relief concept. Makes a lot more sense than what ever he was explaining. Nothing really gets explained so Yeah i see why its turns us all into monkeys.