One more question- were I to use PNP BJT and N-MOSFET how would the connections differ?

These two configurations based on H1 activating and H2 resetting.

Using a N channel mosfet switching the low side of the solenoid.

 

Using a step down buck with I/V control, circuit will be running at 18v / 1A for now.
planning to step it up to some 80v and probably more current though as this will work better (shorter on time)
Prototype need not use such high voltage.

One more question- were I to use PNP BJT and N-MOSFET how would the connections differ?

Same circuit in concept but all devices reversed- but the hall-effect devices can't be reversed so will require additional parts. Better to stick with P-channelMOSFET

 

Were it a "scam" where's the profit to be had??

In selling the idea to gullible investors.

 

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Awesome @Irving and @sghioto thankyou for the help.
That REALLY clears things up for me. Favour owed - could I pay it back I would.

 

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Yeah ok what happens then?

You’d have to study physics to find out for yourself. The Big Bang theory says the universe started as a singularity. There are theories that state once the universe loses sufficient energy, then it will collapse unto itself… to a singularity. And the cycle begins again.

Of course, this is with respect to our universe. String Theory has projected that at any point in our time, there are multiple universes co-existing. I found it easy to understand based on other theories that our universe doesn’t exist in four dimensions, but rather as much as eleven.

This isn’t my opinion. It has been stated by many, including Nobel prize physicist Stephen Hawking.

But I’ve co-opted your thread enough…

 

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For the second diagram with the N MOSFET what resistor values do I use?

 

View attachment 287916

You Sir have gone above and beyond to help. Thankyou for the info

 

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Try changing R4 to a 10K.

 

Try changing R4 to a 10K.

Changed it for a 10k, still no latch.. maybe I have mis-wired something.
the 10k goes between sensor #2 + and digital output, right?
Supply to H2 being on the left, and its output coming out the top?

 

Supply to H2 being on the left, and its output coming out the top?

Supply on top, output on left for H2

 

Supply on top, output on left for H2
View attachment 287924

Now having done that, neither sensor has any effect.
Does it matter if I'm using different switching devices than are listed?
Surely their turn on requirements are different?

EDIT I had the PNP C-E Hooked up back to front. however, same result, no latch.

 

Surely their turn on requirements are different?

Usually. Change R2 to 10K also. Are you sure you have it connected correctly especially concerning the pins on the transistors?
Do you have a solenoid connected? Do you have any other smaller transistors you can use for Q1 and Q2?

 

Usually. Change R2 to 10K also. Are you sure you have it connected correctly especially concerning the pins on the transistors?
Do you have a solenoid connected?

No solenoid connected atm, yet to wind it. Is that needed for it to work? Does the MOSFET require an inductive load to latch, that an LED can't provide?
I do have a coil to hand, if any will do, 8.0 ohm with .3mm wire on it. the real thing will have .8 wire.
I had the PNP back to front (C+E were the wrong way around)

EDIT I have some 2n2222A's (not 2n222A's as stated earlier)
No small PNP's though.

 

Don't need the solenoid to work but need some kind of indicator to see that the circuit is working.
What are using to check that the circuit is working?
Replace the 2N3055 with the 2N2222, keep all resistors at 10K

 

Sensor 1 now latches the FET "ON", But Sensor two acts a "proximity dimmer" which is cool, but still not quite right.
Any ideas?