Intro to coding

No. you just need a large capacitor, See my explanation earlier

I'm going to say yes.

In a way, old fashioned buzzers are just a relay wired through itself.

Add a capacitor a resistor and you should be able to make it oscillate at other (lower) frequencies.

Indeed.

That still leaves hydraulics :)

I might have a play later, if I can find a suitable DC relay and big enough capacitor.

Back in the early 1970s (before most subscribers to this NG were even a twinkle in the milkman's eye?), the challenge was to produce a bistable flipflop with just two relays.

I don't remember the exact solution, but ISTR that it involved trying to prevent re-triggering when a steady level of excitation was present.

Useful, yes, thank you. This course has three "Assignments" that have to be completed and submitted for marking by the distance learning company and the the certification comes from Edexcel. So I guess it's a reduced course of some sort.

He is finding some of it hard going as he has yet to do, at GCSE, what the course is assuming as knowledge from finished and passed GCSE's... As I say he's only in Year 10 (fourth year in old money) so working at or near A-Level is pretty damn good.

Now I know how non-IT geeks feel when us IT types start yammering away in the pub.

a 1/2) - I got the daughter to build an full adder out of 74 series logic...

e) Turn it into a wood working project:

AOL:-)

Mind, I helped my daughter develop a *brake lamp failure* indicator for her GCSE.

Impressive! How many bits? Extra points for having it read 10-position rotary switches to represent the input decimal numbers, and drive a display showing the decimal result.

What, no resistors or diodes? Thankfully, the question posed seems to invite the use of 'relays' in the plural.

You *can* used "special" relays like the GPO used in telephone exchanges. A classic type that comes to mind for this use are the 'slugged' types which can provide a delayed operation as well as delayed release. However, by using more than just a pair of cross-linked relays, it's possible to gain modest 1/2 to 2 second delays[1] using 'ordinary' relays by arranging the coil windings to be in series with a resistor or another relay coil winding whereby a similar effect can be had by shorting the winding to achieve a delayed release.

It's been well over quarter of a century since I last clapped eyes on any N diagrams but I'm pretty certain it's quite possible to create a multi-vibrator from just two relays with pulse cycle times in the region of 1 or 2 per second.

Oh that is so cool!

I love the cascade to the overflow bit :)

I have to do both!

;-)

Just the three to start with...