Electronics - Breadboard multimeter adapter

For some time now I've been looking for a convenient way to probe around my breadboard with my multimeter. It can be a little tricky, because the probes are too thick to get into the little holes on the breadboard.

I had a bit of an idea today.

I came up with this...

It's a stereo headphone jack with a long length of header pin (sturdy wire used as a plug) soldered to the legs.

I added some insulation in the form of heatshrink, and...


The 120 Things in 20 years multimeter breadboard adapter.

Handmade fishing lures - Mold making - Prototyping plastic

I just discovered my new favourite substance.

It's even better than PVC.

Maybe it is PVC.

I don't know.

I was in my local electronics store checking switches, and was sold some of this stuff.

It's plastic that you can warm up and shape.

You need to get it to around 65 degrees c before it melts into itself.

Once hot, you can shape it into anything you can think of.

Pictured here is a bit I squeezed.

It retains fine detail like fingerprints, and when dry, it sets white like the beads again.

It sets to a strong plastic with a little flex, a lot like a soft drink (soda) bottle cap.

My first use was to make a very specific battery pack that didn't exist as far as I could tell.  It's great to work with, and totally recyclable. You just drop it back into hot water, and it re-melts.

I would guess you have around a minute to work with where you can press two bits together and they form one. And perhaps another minute where you can still shape it, but pressing two bits together wouldn't quite become one.

If you need more time to work it, you just put whatever you've half made back into hot water and it softens again.

Very cool stuff that I think I'm going to need to buy in bulk.

120 Things in 20 years is excited about making handmade fishing lures, and just general prototyping  In reality, I have no idea what I'll do with it, but it's exciting just knowing about it. I'm easily excited.

Electronics - Aquaponics - Demand feeder fish lever build

I spent some time in an electronics store testing long buttoned momentary switches.

They all seem to work when you tilt the button to the side as well as when you press the button normally. Perhaps they are designed to work that way after all.

Thanks button maker.

I had a bit of a breakthrough with the entire lever, and not just the switch part. I found this fishing float had a white plastic bit that almost fit over the momentary switch's button.

That's the switch lower right.

The white plastic thing was hollow, but needed a slight enlargement with a hand held drill.

The button went in with a snug fit, and the white thing was really their just to give me some surface area glue onto.

The new lever incorporated a second fishing float as the stem, and as a nice bulb for the fish to hit.

The float stem has a bit of flex to it, so it should be forgiving if a fish hits it hard.

It looked lie this when built.

I glued it in place with super glue, and held it while it dried with what to me looks like a naked chicken with a fist for a head.

So now my device looks like this.

It also works.

I turned it on, and while I was putting a cover over the fish tank, the bigger of my two fish hit the lever and got a feed.

I did have the camera running, but the video was too dark to post, but the switch and lever worked perfectly.

I count this as a success!

120 Things in 20 years suggests you never try to take your electronic aquaponics demand feeder on a plane with you, unless you feel like explaining it for a few hours.

Electronics - Aquaponics - Demand feeder lever

Probably the most difficult single thing to deal with in making my demand feeder has been working out the lever.

But as usual I called upon chance to solve it for me.

Thanks chance.

For some reason I remembered playing with a switch I bought when I was making the first version of this demand feeder. The switch was one that is a button, and turns on then off again after you lift your finger.

It's sideways click seemed nice to the touch.

The one pictured (centre front) is the same, but is on an old circuit board. I cant find my original version.

It's quite long for a momentary switch.

The interesting thing about these particular, particularly long momentary switches, is they they do their switching thing if you tilt the button to the side rather than just press it. I just tested this one and it works.

They also work if you press it, but it's the sideways switchyness that interests me. It should be perfect as the lever the fish hit, because they can hit it from any direction and it should trigger.

Now all I need to do is figure out which brand they are, and if they all work like that. It might be the case that only some of them do this. It might be a manufacturing error rather than a feature.

Perhaps manufacturing error is too harsh.

Perhaps manufacturing  tolerance would be better.

Either way, I might be able to use it.

120 Things in 20 years - As luck might have it, for the next few days, you might find me in electronics stores with a multimeter, trying to find a switch for my electronic, aquaponics demand feeder lever.

Heliostat - What's a heliostat?

I want to start building a heliostat, with the eventual goal of making a solar tracker, but for now, I really want to just build something that will send light through my window.

Why? You may well ask.

And "What's a heliostat?" you may add.

A heliostat is the kind of thing someone with a water drop lensed microscope might have used to get some light on the subject*. Early models involved humans, who were forced to point shiny things in such a way as to reflect the light to shiny men's laboratories. Later versions incorporate wind up mechanisms. For a single day device, all that's required is that it turns 15 degrees every hour, as long as you are willing to manually adjust the elevation for the particular day you are using the device,
a heliostat will track the sun so that a mirror will always reflect to the place I want the light.

The solar tracker is like a heliostat, except that the place it's pointing at is always moving. (that point being directly at the sun wherever it is. But the solar tracker is for another day. Actually all of this is for a great many days.

For now, I'll be working on a small digital device that controls the direction a small mirror is pointing, to make it always reflect light to a fixed point. Basically a way to bring some natural light through a window that doesn't see a lot of light.

There seems to be a few different ways to create some linear movement. Linear movement being required to lift a side of the mirror to adjust the direction of the reflection in the up and down aspect.. I figure if I can raise or lower one side, and make the entire device pivot around a mast, I should have all the degrees of movement required.

According to the invention engine, one way to create the required angle might be to glue a hinge to a mirror, and mount that to a mast to support it. Tie a string to one side of the mirror, then wrap it around a tiny winch mounted half way up the mast, then tie the other end to the other side of the mirror. That would give me up and down, and then all I need is a way to rotate the entire device, perhaps using a geared motor, and a pulley.

I haven't really tackled this bit of the design, but the control of the motors could be done via a PICAXE chip similar to that used in my demand feeder. and some light dependant resistors (LDRs).

If two LDRs were arranged so that when the device was pointing correctly, they were both in full light, but when one became shaded, the motor could be turned in the correct direction to make the adjustment.

A similar arrangement could be made for both the up and down, and rotational movements.

I'm off to an electronics store to buy some stuff.

*may not reflect reality.

120 Things in 20 years is busy finding bits of heliostat. 

Thinking - Fresh produce

Is it just me or is everyone crazy?

Don't answer that, it was a rhetorical question .

I just picked a stack of cherry tomatoes from my aquaponics system. They represent only the second batch that has made it back to the house. All the others were devoured before the back door. But this time, some made it.

Looking at them in my kitchen has me wondering why we insist on having all our fresh produce being uniform in size, shape, and colour. This is a very "developed world" kind of issue, so if you are more sensible than this where you live, just ignore this post, but in this part of the world, almost everywhere we buy fresh produce only sells perfect looking produce.

I wonder what would happen to prices if they just left out one of the criteria for A grade produce.

For example, size.

The size of a fruit is by far the least relevant thing.

The tomatoes harvested were all ripe, all delicious, and all different sizes.

So why would the four on the right be classed as second grade.

It's because...

We are all crazy.

120 Things in 20 years - Where thinking and forming opinions about everyone regarding fresh produce, is often presented as fact.

Aquaponics - Cherry tomatoes

Those crazy cherry tomato plants I have growing directly in my fish tank water are producing some really nice fruit.

This bunch looked like a likely candidate for some photo's so here they are...

Electronics - Aquaponics - Demand feeder hits

It turns out the fish have been hitting the lever, but the switch hasn't been working.

It should be an easy fix, but for the time being, this will have to do.

[edit from the future - I fixed the switch and got a few proper hits with feed delivered within a few hours]

Electronics - Infinite battery life camera

I've had to make a few compromises with version 2.0 of the demand feeder.

One is that I've re-written the code and made it a lot more simple than it was originally. I've still got the old code, and I'll use it and post it when I make it a little better, but the full version resets each day at dawn as one of the overfeeding protection measures. I only have two silver perch in a 100L fish tank, with 300L of filtration media, so they can have as much feed as they like. To encourage the pressing of the button, I've made it so that they only get a small amount of feed each time, but they have the opportunity of more feed after only eight minutes since the last feed. The point of making a simpler version of the software was so that it would keep a running total of all events like the number of times the fish have hit the feed lever when the light is lit, and the number of times when the light isn't lit.

The fish pressed the lever only once in the 24 hours since I added it to the system. This may have just been a tail swipe, but it would have delivered feed, so some reinforcement of the behaviour of getting at least near the lever has begun!

It wont take them long to get the hang of it.

I ran the camera until the batteries were dead last night, but the hit must have happened some time since dawn while the camera was on charge. To solve this two hour filming limit, I created this.

It's a camera taped to it's battery charger, that is in turn taped to a tripod.

I plugged it into the earth leakage safety switch that the rest of the system is plugged into.

It blends in a bit with the actual feeder, but that's the feeder with the birds nest of wires sticking out of the back of it. The orange looking light under the camera is the LED that tells the fish feed is currently available. The red light at the top is the power on LED, and the yellow one is flashing out the number of feeds allowed in a day (even though the thing no longer resets after a day, so really it shows the number of feeds allowed ever). There are also LED's that flash out the number of feeds so far, the feeds remaining, the number of attempts made at the lever when food isn't available. That is when the feed LED isnt lit, because they just fed recently. And one more that flashes out the size of each feed that's delivered. The size is measured by how long the motor is on for, and doesnt actually represent the amount of feed, but on average, should spill a predictable amount each time. Currently, they would get around 5-8, 3mm pellets each time they hit the lever.

Hopefully, I'll have some video soon.

120 Things in 20 years - Electronics - Infinite battery life camera - This project is far from finished.

Aquaponics - Silver Perch update

I recently ran out of fish feed, so I've been hand feeding them worms, and what ever they call fly larvae in whatever part of the world you live.  They are called "gents" here when bought as bait, or stored in a fridge shared with people who don't want maggots in their fridge. "Maggots" when found in smelly stuff.

The point is, as a result of feeding them live food like worms, gents, and caterpillars, they are venturing a bit further up the water column to the point where they are now easy to photograph.

This guy is pretty big.

And heavy looking.

It looks like this up close.

I have no idea how big or how heavy it is, but I'll try to get a photo next to a ruler.

I wont try to weigh it because I cant think of a way to do it without stressing it.

I'll weigh it if I ever eat it.

120 Things in 20 years - Sometimes your aquaponics silver perch get quite big when you're not looking.

Electronics - Zero K breadboard resistor

I always try to not just "take" when it comes to learning a new thing, but this electronics caper has really been worked out already by a whole stack of really clever people.

I cant seem to come up with anything to offer the world, so I came up with this as a forlorn attempt to quench my karmic debt.

It's the zero K breadboard resistor.

It's a wire with a knot in it.

It works just like a wire, but is easier to handle.

It's all I've got at this stage.

My karmic overdraft doesn't seem to have changed.

120 Things in 20 years says, "When thinking electronics, a zero K breadboard resistor can be simultaneously just right, and not quite enough.".

Electronics - Motor repair success

I fixed my broken motor that is meant to power the auger via the tiny gearbox that will deliver the fish food in my demand fish feeder.

Normally I prefer less complicated sentences.

But I'm all excited.

It turns out, the problem was there were simply too many parts.

Or more accurately one too many parts, and one that was simply in the way.

The silver bit was the one too many. I think that broke off the bit where the wires connect, and fell into the motor, generally clagging things up.

The little nylon washer creates part of the front bearing, but it made getting the brushes back on impossible, because it had to be put on after the brushes. That's an impossible path through the plastic front. I don't have the kinds of quantum tools that walking through walls requires. And if I did, I wouldn't waste my time with motor repairs. I'd do much more interesting stuff, like poking my head through the fridge to see if the light really does go off when the door is closed.

So be leaving out those two small parts, I managed to make my motor work.

Only two parts.

And they were tiny.

Those that know me will realise that's a pretty low number of excess bits after a repair. I think I did quite well.

So well in fact, that it looks like this when it's running.

That should do nicely.

What this all means, is that there is really no reason why I cant put this thing together today, and actually finish something.


120 Things in 20 years - If I keep repairing them, one day an electronic motor repair might leave me with enough parts to eventually build another motor. I should fix cars.

Electronics - Aquaponics - Demand fish feeder software

As far as I know, the software is all working on my demand fish feeder.

It's a bit of a mess, with a few goto statements and a few unused variables. I'll fix it in time, but for now I'm going to move onto getting a finished product up and running. As far as I can tell with the software simulator everything works, but the real world might be a completely different story. (the breadboard version also works)

A switch lever extends down into the water. If a light near the lever is lit, the fish can press the lever and feed is delivered. Feed can also be offered with an override button that sets the light on and the feed on if the fish hit the lever (so you can show people how it works)

Dawn detection seems to work. In the end I went with two startup options.

1. A human who holds down the FeedNow override button during startup, then taps out the approximate number of hours since dawn. This skips the code that searches for a new dawn.

2. An abnormal restart with no human. This stops all feeding (there might have been a blackout, and subsequent ammonia buildup) (note to self - add code that flashes some lights to indicate the device is in abnormal start mode so a human can reboot it if they desire). Feeding resumes after night time is detected, and a dawn is detected.

The user can select (via a screwdriver to resist little finger making their own adjustments) ...

 - the feed amount per day in tenths of a second of motor on - from 0 to 65 (I'm guessing I'll use 1/2 a second per feed event) The motor turns an auger under a hopper full of feed. So there is another adjustment available

- The number of feeds in a day that are offered (0 - 255 per day)

- The level of light at which dawn is detected. This allows for a system built in the glow of a streetlight or whatever. At dawn each day, all the numbers reset. This is a bit of a problem as far as reading how many feeds were delivered in a day, but for now I'll leave it as it is. My fish feed like crazy at dawn, so I want to give them the greatest opportunity to feed. Eventually I'll add a data logger, so it wont matter when it resets.

The system reports...

- the number of hours since dawn

- the number of feeds since dawn

- The number of false hits to the feed lever when the FeedIsAvailableLED is NOT lit (these will go down to near zero once the fish learn they can only get food when the light is on)

I ran out of feed a while back, and have been feeding my two big silvers on duckweed, lettuce, and worms, so I will need some pellet food before I can test it in the real world. (I still have the PVC device from the first version).

I'll also need a motor as my original one is no longer with us.

The feeding regimen isn't very intelligent at the moment, but I'll do a bit of research, and add some code that tries to deliver the maximum amount of feed in a day that the system can handle. This will probably involve allowing 3/4 of the feed to be dumped at will, with the rest being spaced out over the day ... or something. I haven't given it enough thought because I don't really know what the fish need. My experience in fishing for wild fish indicates that the feeding pattern is far from a constant grazing all day long. I'll work it out.


It's going to work. In fact, it already does.

120 Things in 20 years That's all. Just 120 Things in 20 years.

Aquaponics - External Tomato growing in fishtank

I've been away for a few days.

It was nice.

One of the best things about aquaponics, is the fact that it takes care of itself. I came home to a system overflowing with produce, and with lettuce that was ready to eat, where when I left, it was nowhere near ready. It's amazing what a few days can do.

Also, not seeing my system for a few days made me realise just how big my tomatoes were getting.

That's them hanging off the side of the little grow house.

I'm calling this experiment a complete success. I had to tie the foliage to the growhouse to support it, because it was starting to pull the roots out of the water.

There's fruit forming everywhere, and in spite of the late start due to pruning it all back to only a few leaves, I think it will be a good season. Once the capsicum season is over, I think I might just pick up the tomato, and move it back inside for winter.

The tomato grows through a PVC pipe to stop it growing inside the growhouse, and the roots are all just hanging inside the fish tank. There is no media involved, and it relies on the water being oxygenated by the water movement, and the nutrient it gains from the fish.

This has been a lack luster post.

I'm sleepy from too much driving.

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