Warning Do not get a qualification with ICS Learn in the UK (BTEC L3)

[Simon]

Yes that is pretty much what I would of said but I would not have been as succinct. When the question of the video was raised on the ICS learn forum and the course administrator basically said the video was not necessary she was in effect trying to drop the inconvenient bit. When we challenged her she never clarified as to which circuit the video was supposed to be of. So as for comprehension of the assignment I rest my case.

[rexxar]

It doesn't tell you to build that circuit, only to explain it. However, there is the instruction to record a video of yourself building it, but that bit of text is pasted at the end of every section, it's not hard to imagine that it got put there by mistake. Considering that you weren't supplied with a FET, nor given any part numbers or values, it seems clear that you're not supposed to build that circuit.

I've only skimmed over the assignment, but it seems to be fairly reasonably done. Certainly not the outright scam you seem to think it is.

I get that it's easy to see every little problem as a huge fatal flaw when you're pissed, but really every time you've talked about this, you seem to get really defensive when anyone points out that it's not actually that huge a deal. Surely you realize how preposterous it sounds when you say that the whole course is completely broken and unpassable? If it weren't possible to even pass this course, surely someone else would have noticed.

[G0HZU]

Here's the transfer characteristic of a small N channel depletion mode MOSFET.
You can see it does self bias at 0V Vgs so figure 1c will work with small signals but I doubt you would get much voltage gain from it. Maybe it could be used as a (fairly crude) Hi Z to low Z buffer for small signals?


It's not anything like as common as the N channel enhancement mode MOSFET that most people know and understand (and use in industry in vast qty)

[IanB]

Surely the key thing is that in the course you are not supposed to get caught up in details of N channel or P channel, depletion mode or enhancement mode? Those are advanced concepts for the future. At this level I think you are only expected to recognize that other kinds of transistor exist, such as the FET, and these other transistors can be used as an amplifier in much the same way that a BJT can be used. Details of their design and operating characteristics can come later.

[G0HZU]

Surely the key thing is that in the course you are not supposed to get caught up in details of N channel or P channel, depletion mode or enhancement mode? Those are advanced concepts for the future. At this level I think you are only expected to recognize that other kinds of transistor exist, such as the FET, and these other transistors can be used as an amplifier in much the same way that a BJT can be used. Details of their design and operating characteristics can come later.

I completely agree and that's why I see question 1c as a poorly worded question that will trap and confuse. Especially those hobbyists who use the commonly available enhancement mode devices. The circuit symbol for each type is very similar and this will trap a lot of people. I doubt many will ever buy an N channel depletion mode mosfet for use in general hobby projects. Radio hams commonly used them in preamps many years ago though.

[Simon]

The depletion mode mosfet was never mentioned, like i said only MOSFET and JFET and while biasing of the BJT amplifier was roughly explained this was not done for the FET variants so can lead to confusion, like i keep saying you are all thinking way over the level of this course. Personally I think the author may infact be knowledgeable but totally incapable of writing things in a simple enough way to get simple concepts across, instead he makes an utter pigs ear of explaining some things either alluding to a more advanced concept when not necessary or simplifying to a degree that makes the explanation pointless. The whole explanation of the FET and it's amplifiers lasts exactly 3 pages, that's it.

At the end of the day you would hope that rather than gloss over everything less topics would be covered to a level where the information is actually useful for something. None of the information in the course is sufficient to design anything from scratch. Even the BJT explanation lacked an explicit mention of gain never mind a proper explanation. I think the word gain featured once.

[Simon]

The other problem is that when in doubt a tutor was totally unavailable, it took 6 weeks to get hold of someone and patchy contact from then on. Totally not as advertised.

[Simon]

Here's the transfer characteristic of a small N channel depletion mode MOSFET.
You can see it does self bias at 0V Vgs so figure 1c will work with small signals but I doubt you would get much voltage gain from it. Maybe it could be used as a (fairly crude) Hi Z to low Z buffer for small signals?


It's not anything like as common as the N channel enhancement mode MOSFET that most people know and understand (and use in industry in vast qty)

check my video toward the end, it shows you exactly what you get. the transfer characteristic as you show is certainly not linear, I think the basic concept of an amplifier as you would want to explain it in a simple BTEC L3 course is that the in/out relationship is linear. My video shows that you cannot consider the circuit presented a linear amplifier at all although the bit above 2V in the signal could be considered sort of linear, it's hard to tell when the rest of the signal is not being amplified because the circuit lacks biasing.

Of course let us not forget that the course teaches that I can use a crappy non RMS multimeter to measure inputs and outputs....................

[G0HZU]

My video shows that you cannot consider the circuit presented a linear amplifier at all although the bit above 2V in the signal could be considered sort of linear, it's hard to tell when the rest of the signal is not being amplified because the circuit lacks biasing.

For your version of the circuit, yes. Because you used an enhancement mode device that is pinched off at 0V Vgs. But of course, the circuit in figure 1c (as drawn in the assignment) 'will' give linear operation for small signals because it uses a depletion mode device that self biases at 0V Vgs. So at 0V bias at the gate it will operate with an idle drain current of somewhere around 10mA to maybe 100mA depending on the device that is chosen.

[Precipice]

Of course let us not forget that the course teaches that I can use a crappy non RMS multimeter to measure inputs and outputs....................

If the output isn't distorted, then the gain will show as the same on both a crappy non-RMS meter as on a spiffy RMS meter.
If the wave is distorted, then no multimeter is going to show you much of interest (except maybe that the DC bias is wrong enough to be the cause of the distortion).

Relying on the 'RMS-ness' of a meter, and telling yourself it says very much about an amplifier, would be a bad choice. I'd suggest that a crappy old meter is fine for this sort of poking around, and that an oscilloscope is the next step up, not a better meter.

[G0HZU]

In my opinion some of your course material appears to be based on older technology in days when single gate N channel depletion mode MOSFETs were quite common.

Try and buy one today and it will probably have the wrong transfer characteristic because it will probably give a very high idle current at 0V Vgs.

If you want to get hold of a suitable N channel depletion mode MOSFET 'today' you might be best to get hold of an old dual gate mosfet and tie the gates together to replicate the circuit in figure 1c. The chances of finding an old school single gate device are quite slim and they could be quite expensive.

I've got some dual gate devices here that might work OK with the gates tied together. Ideally you want to find a device that has about 2mA to 5mA drain current with 0V Vgs applied.

[G0HZU]

I'm a bit bored so I built this circuit quickly.

It uses an old school BF981 dual gate N channel depletion mode MOSFET transistor which is probably older than most forum users... 

By tying the two gates together it effectively becomes the circuit in figure 1c in the assignment. I used a 1k resistor in the drain and something 'big' in the gate (220k ohm?)

The supply is 12V and it runs at about 6mA drain current. See below for the crudely built circuit and the waveforms on my scope. It gives a reasonable amount of voltage gain and is fairly linear. Basically, this circuit in figure 1c would have been an exam question in the 1970s or maybe the 1980s.

I'd probably be asking the tutor where I was supposed to buy a suitable device in 2014 because I doubt there will be much choice especially if you want a device that biases with just a few mA at 0V Vgs.

[zapta]

Hello everyone and you may remember a while ago I was complaining about my BTEC level III course in electronic engineering. After a lot of arguments they have mostly refunded my employer. Basically because I became such a thorn in their side that they did not want me to have access to their forum any longer where I was leading the discussion on how bad the course is.

Simon, I am sorry to hear that you failed the BTEC L3 program.

This calls for an honest introspection on how come an intelligent person such as yourself failed and will not get the diploma while others students will.  Probably this is not the first time this patterns occurs but you can try making it the last.

BTW, the long justifications are meaningless, if you need to explain you failed. Period.

[ejeffrey]

BTW, the long justifications are meaningless, if you need to explain you failed. Period.

That kind of rudeness is just uncalled for, and a mark of poor character.

[zapta]

BTW, the long justifications are meaningless, if you need to explain you failed. Period.

That kind of rudeness is just uncalled for, and a mark of poor character.

No, this is a sincere reality check. The long explanation is a distraction. Lesser students will get the diploma but he will not.

[Simon]

My video shows that you cannot consider the circuit presented a linear amplifier at all although the bit above 2V in the signal could be considered sort of linear, it's hard to tell when the rest of the signal is not being amplified because the circuit lacks biasing.

For your version of the circuit, yes. Because you used an enhancement mode device that is pinched off at 0V Vgs. But of course, the circuit in figure 1c (as drawn in the assignment) 'will' give linear operation for small signals because it uses a depletion mode device that self biases at 0V Vgs. So at 0V bias at the gate it will operate with an idle drain current of somewhere around 10mA to maybe 100mA depending on the device that is chosen.

again you assuming the course material taught all of what you are talking about. If the course does not teach the student cannot use untaught knowledge to pass an assignment.

[Simon]

Of course let us not forget that the course teaches that I can use a crappy non RMS multimeter to measure inputs and outputs....................

If the output isn't distorted, then the gain will show as the same on both a crappy non-RMS meter as on a spiffy RMS meter.
If the wave is distorted, then no multimeter is going to show you much of interest (except maybe that the DC bias is wrong enough to be the cause of the distortion).

Relying on the 'RMS-ness' of a meter, and telling yourself it says very much about an amplifier, would be a bad choice. I'd suggest that a crappy old meter is fine for this sort of poking around, and that an oscilloscope is the next step up, not a better meter.

Well I don't know the finer points of multimeters, it just strikes me as a bad idea and does not allow for circuit diagnosis like a scope does. Fact is without my scope I could not have demonstrated the problems and my circuit would have had a lower output than input and had i been a student who had studied from scratch I'd have been non the wiser. We keep assuming here that your average student knows all that you people know when infact the course material teaches next to nothing and then the assignment needs the sort of knowledge that you gain from higher qualifications just to fix it.

[Simon]

I'm a bit bored so I built this circuit quickly.

It uses an old school BF981 dual gate N channel depletion mode MOSFET transistor which is probably older than most forum users... 

By tying the two gates together it effectively becomes the circuit in figure 1c in the assignment. I used a 1k resistor in the drain and something 'big' in the gate (220k ohm?)

The supply is 12V and it runs at about 6mA drain current. See below for the crudely built circuit and the waveforms on my scope. It gives a reasonable amount of voltage gain and is fairly linear. Basically, this circuit in figure 1c would have been an exam question in the 1970s or maybe the 1980s.

I'd probably be asking the tutor where I was supposed to buy a suitable device in 2014 because I doubt there will be much choice especially if you want a device that biases with just a few mA at 0V Vgs.

you are still assuming the course was going to teach me all you know, like i said, the sum total on mosfets and mosfet amplifiers was 3 A4 pages - with big diagrams.

[Simon]

Hello everyone and you may remember a while ago I was complaining about my BTEC level III course in electronic engineering. After a lot of arguments they have mostly refunded my employer. Basically because I became such a thorn in their side that they did not want me to have access to their forum any longer where I was leading the discussion on how bad the course is.

Simon, I am sorry to hear that you failed the BTEC L3 program.

This calls for an honest introspection on how come an intelligent person such as yourself failed and will not get the diploma while others students will.  Probably this is not the first time this patterns occurs but you can try making it the last.

BTW, the long justifications are meaningless, if you need to explain you failed. Period.

you obviously got very distracted. I did not fail, I refused to continue with the farce. Remember, you have not seen the actual course material yet, it is an insult to anyones intelligence. It would have been much more productive if they had just sold my employer the assignments and a list of topics I'd need to study in order to do the assignment. The actual course material is poppy cock! every topic ended with a section telling the student to go online to read the same thing again but written in a competent fashion even if it is joe bloggs hobby blog. They also supplied a text book just to make sure they had it covered.

Fact is the guy that will fail is that poor sod that is studying while working at sea with no internet access or to alternative components in the kit, tell him to solder wires onto a potentiometer so that it can be used. Whoever chose the parts for the kits was totally incompetent and had no understanding of what they were ordering, infact the pot turned out to be a double one.

[Simon]

BTW, the long justifications are meaningless, if you need to explain you failed. Period.

That kind of rudeness is just uncalled for, and a mark of poor character.

No, this is a sincere reality check. The long explanation is a distraction. Lesser students will get the diploma but he will not.

If you want a long explanation would you like to see the reels and reels of emails I have ? I raised concerns about the accuracy of the material soon after receiving it.

[bwat]

That kind of rudeness is just uncalled for, and a mark of poor character.

No, this is a sincere reality check. The long explanation is a distraction. Lesser students will get the diploma but he will not.

I have to agree with zapta.

This calls for an honest introspection on how come an intelligent person such as yourself failed and will not get the diploma while others students will.  Probably this is not the first time this patterns occurs but you can try making it the last.

Nail hit firmly on the head.  Put your engineering hat on and see it as negative feedback.

There is an aspect of learning which involves reading comprehension and carefully following instructions.

Again, someone else who is spot on. I see a lot of people on these boards who seem to either

i) have a problem with reading comprehension, or
ii) they "read" what they expect to be written and not that which actually was written.

Either way it's a serious limitation.

[Simon]

except this is not a diploma, it's a playschool certificate. It's just a L3, L5 gets you a decent certificate, L8 is the only one called a diploma - HND - Higher National Diploma

[Psi]

There is definitely a link between having pre-existing electronics knowledge and finding electronics qualifications difficult, i've seen this first hand. 

It's quite often necessary when teaching to flat out lie about how something works, or at least bend the truth, in order to make the concept simple and easier to understand. Once the concept is understood you can build on it.
Only much later does the lie become obvious, but you need all the "semi-true" concepts in your head in order to grasp the big picture.

And that approach causes problems with people who already know the big picture when starting the course.

[AndyC_772]

I agree. My A-level electronics course was pretty bad; the course material was outdated and full of mistakes, and the teacher I had was clearly learning the same material from the same course books at the same time, albeit a bit more slowly.

But: passing that course was a tick in a box that got me into university, which in turn was another tick in another box that got me my first job, and subsequently, a career in the industry. I wouldn't be where I am today if I hadn't passed that course at school over 20 years ago.

That's why I think it's a big mistake to drop out of a course before completion, regardless of how bad you think it is. Pass the exam, get the tick in the box, THEN complain about it if you still feel it's necessary.

Prospective employers will not, I absolutely guarantee, care why you failed to pass the course. "If at first you don't succeed, destroy all evidence that you tried" may be good advice.

[bwat]

Prospective employers will not, I absolutely guarantee, care why you failed to pass the course. "If at first you don't succeed, destroy all evidence that you tried" may be good advice.

Depends. If he goes on to get a higher qualification or can demonstrate competence with either a good portfolio or an ability to confidently answer technical questions, then not many would hold it against him. He can easily argue that failure to finish is a case of getting out of a bad situation, and not because of an inability to learn.