Golborne Meeting 8th April

[Keithstv]

It's under 2 weeks to the Golborne swapmeet. I'll be going, with my name badge , aiming to arrive around 10am.

I'll be giving a talk titled "An Introduction to Semiconductors part 1 - Diodes and Rectifiers" in the side room at around 11:30. This is the talk I intended giving last November before domestic issues got in the way. I'll be giving part 2 of the talk on transistors and ICs at the November meeting.

If anyone has any diodes they'd like to see the characteristics of please bring them along and I'll put them on my simple curve tracer.

Last year I asked if anyone had any metal rectifiers I could borrow for the talk and received several diodes and rectifiers which have proved useful for the talk but I have mislaid a few of the labels I put on them to identify the owners. If you have sent me any diodes and can identify them you can have them back after the talk. Alternatively I can take them to NVCF to return them to their original owners.

There's no need to book a seat at the talk just turn up around 11:30.

Keith

[Terry]

The BVWS site says on its events location page: "Some information about the venue with a map is available here." but, unfortunately, the link produces a 404 error.

[Diabolical Artificer]

I'd love to go, but won't be able to so will unfortunately miss your talk. Any chance of someone filming your talk Keith and bunging it on Youtube? I'd happily upload it if some can do the filming.

Andy.

[Keithstv]

That has been suggested by a friend of mine but it does require a bit of preparation which unfortunately I don't have the time to do. However I will be publishing the notes for the talk on this and the UKVRRR forums.

Keith

[Keithstv]

Although the talk was slightly delayed due to the room being used to store the left over decorations for an anniversary party the previous night which needed moving, the talk went ahead.

I've attached the notes for the talk which is part 1 covering an introduction to diodes and rectifiers. At the next Golborne meet in November I'll give part 2 covering transistors and integrated circuits.

Keith

[ppppenguin]

What a great and wide ranging set of notes. You obviously did a lot of research and hard work to put that much useful information into a few pages of clearly presented information. When preparing talks like this you've obviously thought hard about your likely audience. Lots of information about the practical characteristics of diodes with a minimum of quantum physics.

[Keithstv]

That's probably because any quantum physics I ever learnt has been lost in the mists of time so keeping it simple makes it easier for me!!

Keith

[ppppenguin]

Band gap: The separation between the London Symphony Orchestra and the Berlin Philharmonic Orchestra

Dope: This is a family friendly forum

Germanium: Ask at your local garden centre

LED: A toxic element. Commonly found in airships

[Crackle]

An excellent article Keith. even I could understand it, some useful knowledge gained.
Thanks
Mike

[Terry]

The first varicap tuner I encountered was in late 1969 - a special VHF tuner covering 45 - 230MHz - using the BB105 varicap diode and designed/manufactured by AB Electronics.

This was before the TAA550 was developed (I'm not sure when varicap tuners started to appear in domestic TVs).

In this case, the problem of producing a stable varicap tuning voltage was to use a zener string with an overall temperature coefficient designed to match that of the varicap diodes. It consisted of three 6.8V zeners in series with three 3.3V zeners. As can be seen from Keith's graph, the temperature coefficient of these two values straddles the zero line, resulting in a small overall positive temperature coefficient.