Making slow progress

I haven’t posted in some time as I’ve not made much progress on finishing the electronic system for the new prototype. Life, with all its complications, has interfered and between maintaining my house and property added to some health issues that involved a hospital stay, I haven’t spent much time in my shop. To be honest, as that the last prototype didn’t show even the smallest hint of working, it made it hard for me to maintain my enthusiasm.

However, it setting up the new system I’ve re-examined everything and made more careful measurements. There is a real possibility I didn’t have the phasing correct in my last attempt, and as it blew up after running for less than a minute, I never did get the chance to do anything beyond one quick look.

Phasing is critical, but it’s very hard to get right. Remember, I need to make sure the field coil’s expanding magnetic field is in phase with the increasing current flow in the core. And the only way I have of achieving this is with an oscilloscope looking at voltage changes at various points in the wiring. If I measure the voltage at wrong point or the wrong way, then it can look in phase but isn’t.

When I duplicated my previous wiring, but changed the way I measured things, I got this:

Scope

If these two signals were in phase, their peaks and valleys would appear lined up vertically. As you can see the top signal is following the bottom waveform by almost 90°.  Which means the magnetic field and the current weren’t working together.

I’m not sure this was happening in the prototype that blew up, but as I never got a chance to experiment, it remains a possibility. Getting the phasing right makes all the difference, so I’ll take my time before heating up the new prototype.

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