Electronics - New revised layout

After a great deal of re-thinking (the shop didn't have the stock so I went with the old plan) I've decided against adding a second section of board at 90 degrees to the first.

My demand fish feeder will have to have it's original layout after all.

But I did manage to buy some 10k trim pots.

When you fry around in a plane, there is a way to make the plane do things like turn to the right, and a way to set the plane so it always turns a bit to the right. This allows you to keep the plane pointed slightly into the side wind so you keep going straight. This is called adjusting the trim.

I think.

I read that somewhere.

I cant fly planes or anything.

I just read about trim.

I think.

Anyway, I also think that's the kind of reason trim pots are called trim pots.

The pot bit is potentiometer (volume knob, variable resistor) and what they do is change the amount of resistance they offer depending on the position they are set at. These ones are set with a screwdriver and are normally used to fine tune or trim something before you close up the case and use the controls designed to be used by hand rather than a screw driver.

The 10k stands for 10,000 ohm.

Ohm is a measurement of resistance.


Wire has a low resistance, air has a high resistance, and people have a resistance somewhere in between. That's why we use wires to carry our electricity, and try to keep some air between the power lines and the people.

So when I set the dial on my trim pot with a screwdriver, my PICAXE chip sees a value based on the amount of resistance. The chip translates that into a number between 0 and 255. And then I write some software that says something like...

if its 0 to 9 then theNumberOfFeedsPerDay is 1

if its 10 to 19 then theNumberOfFeedsPerDay is 2

if its 20 to 29 then theNumberOfFeedsPerDay is 3

etc

This gives the user the option to set up to 25 feeds per day.

So the device can be told that the user wants their fish to be fed, say, twelve times a day. As the user turns the dial, a light flashes out the value with a long flash for 10's and a short flash for units. So 12 would flash..

    Long   short  short

The device knows what the human wants, and the human knows where the device is at.

As for the new layout, it looks like the original planned layout.

The three trim pots are on the left with their LED's behind them.

Next is the mode button to switch between normal operation, setting the number of feeds in a day, setting the size of each feed, and setting how much light will be named as dawn, where the user happens to live.

Dawn will be the reset time each day based on light levels.

The last of the new components will be the power switch seen standing upright in the centre at the front.