PICAXE reliabililty


Senior Member
Last year, our daughter and son-in-law had their basement flooded because of a blocked drain at the bottom of the outside stairway to the basement. Seeing an opportunity to use a PICAXE, I built a device to monitor the water level near that drain. <A href='http://www.picaxe.us/WaterLevel-08.html' Target=_Blank>External Web Link</a>
It was installed in July, 2006, and has been silently hiding in a corner of the basement until this week.

My daughter called to tell me that after weeks of dry weather, they had serious rain during the night and were awakened around 1:30AM by a &quot;beeping noise&quot;. On investigation, the beeping noise was coming from the Sonalert on the water alarm because the drain was blocked with leaves - but the water level was still below the threshold, so no water had entered the basement. They cleared the leaves from the drain and went back to bed.

Thank you to a reliable little bit of magic smoke encased in plastic ;-)



Senior Member
Exactly what I'm looking to do in conjunction with the SimpleLAN for a house I will be leaving vacant in a couple of weeks. What parts did you use for your float switches, and where did you find them available. Also, what was the purpose of having a &quot;minor&quot; and &quot;major&quot; float?
This isnt the same thing, but it proves the reliablilty of picaxes for those sorts of applications.

A few years ago my Dad built some solar panels to heat water using the sun. He wanted to reduce his heating bill by allowing sun warmed water to flow into an immersion heater.

He asked me to make a control system to control the water flow by turning a solenoid on and off depending on the temperature differential between the solar heated water supply and the cold water supply.

I ended up using a picaxe 18 for that. Its been running without issue for about 2 years now.


Senior Member
Minor alarm to indicate water is present (at a not-yet-problematic level). Major alarm to indicate water is high enough to cause problems and/or turn on a optional solid state relay that controls a sump pump.

One of the float switches was obtained from <A href='http://www.skycraftsurplus.com/index.asp' Target=_Blank>External Web Link</a>
Float Switch Part#: SK1468 $2.95US in 2006.

The other float switch was found on Ebay (don't remember the details). I'm using inexpensive switches with plastic floats. The dealer on Ebay also had some in stainless steel.



Senior Member
Australian monthly &quot;Silicon Chip&quot; <A href='http://www.siliconchip.com.au' Target=_Blank>External Web Link</a> featured a Picaxed water level circuit in their July 2007 issue. The paradox of course is that much of Oz. has mega water <b>shortages </b> ...

D n T

Senior Member
Another source for the float switches.
Try an auto wrecker, the switches are often used in the bottom of diesel fuel filters, they screw into the bottom of the disposable cannister and they float on water but not diesel, thus providing an alarm ( once again) for the water level.
Or you could get them from a parts store, I think if you ask about the fuel filter sensor in a Toyota Land Cruiser (Australian) the parts bloke will know what you are talking about. While you are there get a new fuel filter and spark plugs for your car, because if these foul up they cause your car to use more petrol$$$.

Jaycar have a float switch as well, it pivots up although it appaers more suited to the side of a tank.


Senior Member
What about to build one, with one small tilt-switch (mercury bubble, quiksilver) attached to one small fishing buoy?



Senior Member
With the current prejudice about mercury I suggest using a reed switch capsule and magnet on a float....


Senior Member
Two problems with mercury switches:
1. pollution if the glass breaks - ingested mercury can cause neurological damage
2. mercury switches don't have a positive switch point - there is a lot of &quot;slosh&quot; when the switch is moved.

The float switches which use a reed relay as the contacts and a magnet in the float itself avoid both these problems. Nothing liquid to pollute the liquid being sensed and the magnetic reed switch has hysteresis, so the float must drop below the &quot;turn on&quot; position to turn the switch off.