Posted by not done it yet on 09/01/2020 11:48:15:
Video or pic? Could be a difference between ‘looking at’ and ‘using’. However, eye protection should be the order of the day whenever in that working area – there may be others making flying chips! Most certainly not a good advert.
It was a video ndiy, the chuck was spinning and the young operator had his hand on the controls.
When my son attended a basic electronics course at the same TAFE (prior to joining the Royal Australian Navy) he mentioned that all of the function generator kits that the students were constructing were going up in smoke. As he was yet to complete his I asked him to bring home the circuit diagram and the suspect part.
It was a 50µA analogue meter that had been 'converted' to read to 1A by somebody sticking a new scale onto the face. No shunt had been fitted. The students were also required to pay $20 for this 'conversion'.
I sat down with my son, explained the problem and asked him to calculate the value of the required shunt. It was some fraction of an Ohm and I said that such a low value would be impossible to purchase so we would make one. Went to the workshop, gave him a coil of nichrome wire and showed him how to measure the resistance of about 5m then calculate the required length, This was wound onto a 4.7MΩ resistor and worked perfectly. He also made one for his friend. They were the only two people to pass that phase of the course. (I still have the device in my workshop).
I went to the TAFE to complain, had to make an appointment in writing then went to a meeting a week later with the head of the department, his assistant and the teacher in question. Was served nice coffee and biscuits and told that mistakes happen. I simply requested that the students who had failed be re-tested and refunded for the faulty meters,
It was only after I threatened to visit the local newspaper editor that they reluctantly agreed. I also asked the 'teacher' to explain how to calculate the value of the required shunt resistor. He could not – mumbled something like 'he never had his calculator with him'.
Sorry about the saga but it still makes me mad that such people are out there and protected by the system.
* Danny M *