Tell us about yourself!
Sincere apologies for any offence to you, my concern was directed generally at the education system in the UK which I have worked in. I now run an electrical engineering company. Sadly ed' here is filled with apathy, lack of control, increasing violence. So apologies to you personally and I do not want to get political and keep to the instructable which was good and informative.
Out of interest sir, a tool I find indispensable in my box is the RF cable tracker commonly used by telecom engineers. A quick way to localise the fault without even removing bulbs or invading insulation. Seasons greetings to all.
With due respect, your comment about teaching electricity but not having seen a basic schematic of a series circuit gives me great concern. Series and parallel are something a teacher should know without needing a schematic.
Fair comment sir, it may be that I have seen it before and it is usually the 3rd wire that catches people out. However my comment was about "teachers" these days. My own son is in his final year of school and I find that what they do not learn these days or what their teachers can not answer from pupils leaves the education system lacking. The instructable itself is very informative and useful, a great clear guide to many people of all skill levels.
why do you use 5 turns of wire instead of the primary pins on the transformer base ?