Recent content by neilparker62

Diophantus Book II Problem VIII. To divide a square (of a rational number) into two other squares - also of rational numbers. Let the first of these be N and the second an arbitrary multiple of N diminished by the square root of the chosen square. Solve for N.

All the best - can scarcely even imagine what it takes to be a PF admin!

Apologies so long responding. We are using 230 volt contactors and the same for the contactor control coils.

Yes - I have now taken a few pics of the same area of sky and the 'smudge' persists. So it's not some aberration of the camera. Also our light polluted but otherwise clear sky picks out very clearly neighbouring stars which can be identified from Stellarium. The "smudge" seems to be positioned...

Delphinus: 26th July 2025 05:10am Taken from (approx) -26 degrees S, 28 degrees E.

Great pic - yes perhaps this is the direction I need to take. Thanks for the info.

Yes - at the moment all I have is a tripod. And I do get the trails as you say but even so I think Andromeda is visible in this pic albeit 'under-whelming'. Smudgy dot at lower centre if I'm not mistaken. Camera is pointing directly North. 2025/07/05 / 05:42:24. My location: -26.153011...

I had in mind something like we see here: https://www.blog.jimdoty.com/?p=31403 although even here the kit being used is a bit out of my 'league'. I will start by pointing my camera in the right direction and seeing if at least one can pick up a 'smudge'.

Great article - it will take me some time to digest the Maths but the graphs show clearly what is happening 'in transit'.

What should a graph of induced emf look like if you have a relatively short bar magnet falling through a long coil ? Let's say the north pole is first to enter. So as it approaches a North pole will be induced in the coil which then looks like a N-S bar magnet. When the magnet exits , the south...

Wish I had kit to take pics like you guys are taking! Practically speaking I guess the next step for me will be some form of telephoto lens. I might at least get some resolution on objects such as M7, What minimum would I need to resolve Andromeda as a galaxy ? Edit: could you perhaps take a...

The Pointers. 19th June 2025

230 Volt AC contactor control coil(s). I should mention that in post #22 snubbers designed for the direct AC load are working but the switching is a bit "iffy". Contactors are on order and we intend putting them in. So we do need snubbers (or other electronics) to handle the transients from...

The relay set we are working with is the one in the pic above which I will repeat here: Each relay has 3 output terminals: the no, the common and the nc as shown at the top of the board. They are just switches - nothing more , nothing less. Input pins showing at the lower right are driven...

Well here's a very thorough operational explanation from Chat gpt. We've included snubber circuits mainly to protect the relay contacts from arcing and (as mentioned above) we've decided that the relays are not good enough to drive AC motors directly so now they are shown driving control coils...