Electronics - Final board layout

At last it's decided.

I've settled on a hybrid between the two previous designs for my demand fish feeder circuit board layout.

Now we have a small extra board set at 90 degrees for the two momentary (press them on then they go off when you let them go) switches, and the power switch will be on the battery pack.

The board also extends below the main board to allow room for some labels.







There will be three trim pots for in-field adjustment, and this will create settings for the maximum number of feeds per day, the size of those feeds, and the last will be to calibrate when dawn is detected.

I'm not really sure how I'll implement the dawn detection, but it will probably rely on some kind of requirement for an increase in light levels over an hour or something.

Due to the fact that I'm running out of pins to use on the PICAXE 14M2 chip, I only have room for two LED's (lights) to flash out the values for the 3 trim pot settings. This will be dealt with by by having the mode button switch between each 3 trim pots, and the normal operating mode.

The two internal lights will indicate the values by flashing.

• When the "Feeds" trim pot is being adjusted, the green LED behind it will report it's value.
• When the "Size" trim pot is being adjusted, the red LED behind it will report it's value.
• When the Dawn trim pot is being adjusted, both the red and green LED's will flash out it's value.

In experimentation, this has proven to be quite intuitive, and easy to read. 

The dawn setting will probably never have to be adjusted once it is calibrated to local conditions to take account of street lighting etc, so was the obvious choice for not having it's own light.

The other two settings might be changed one a month or so, and as a result were deemed to be more important.

The placement of the buttons on the new circuit board, also allows for my absurdly clever water proof switch idea, allowing the "Feed Now" button to be pressed from the outside.

Which is nice.

The "Feed now" button will light the lever indicator light, telling the fish if they hit the lever some feed will be delivered. This function is in anticipation of the user (me) being overly excited about their new fish feeder, and wanting to see, or show others, the fish triggering the lever to receive feed. It will override the forced wait between feeds, but the feed will still be counted and deducted from their total allowed feed for the day.

120 Things in 20 years, not just Electronics - Final board layout, but also absurdly clever waterproof switch ideas!