After the critical and box office success of its recent series of short films, THe Long Paddock is proud to present its first full-length feature, “Sand Wars”, filmed on location at Lancelin.
All posts by Tim
Fishing at Hamelin Bay
We took our visitors to Margaret River to see the stringrays at Hamelin Bay. Further down the beach a crowd was gathering to watch a group of people circling something in the shallows. Thinking it was a beached whale or dolphin rescue, we went to join them. It turned out to be a team of professional fishers landing a school of Western Australian Salmon they had netted.
Viewers are warned that some fish were harmed during the making of this film. Amateur fishers are also warned that they may suffer size-envy.
Please Don’t Feed the Stingrays
As you know from our previous post “Hamelin Bay, WA, home to giant stingrays”, the stingrays at Hamelin Bay interact with people along the shore line, presumably because they are accustomed to being fed by them. Though not apparently enforced, the advice from the Parks and Wildlife Service varies from feed them fresh fish but not frozen bait to don’t feed them at all because they are getting fat.
Inspired by that, the following video is a sequence of skits made by (somewhat randomly) combining the better clips from our cameras with (silly) audio and visual effects.
Cycling to Busselton Jetty
Staying near Busselton, there was an excellent bike track into town. Sealed with occasional, minor gradients, it was a 23km round trip.
Following the submarine testing of Helen’s new GoPro at Greens Pool, we undertook further testing, this time on land-based, self-propelled-transport. Results follow …
Snorkelling at Greens Pool
While staying near Walpole on the south coast of WA (blog post), when we asked locals about swimming and snorkelling beaches in the area the unanimous answer was Greens Pool. On arrival, it was easy to see why.
“Greens Pool lies on the edge of William Bay National Park and is famous for its turquoise green waters and pristine white sandy beach. Large granite boulders surround the pool, protecting it from the might of the Southern Ocean.” Parks and Wildlife Service
My Mains Monitor 2.0
Problem
Avid readers will recall a previous post My Mains Monitor, which described a simple circuit designed and built to alert us to mains power failures.
Every so often, the mains power circuit breaker in the van trips for no apparent reason. Sometimes, it even trips for a good reason (air-conditioner + hair dryer + microwave oven + etc. >15 amps). Keeping an absorption fridge at temperature in very hot weather can be challenging. We went to bed one night expecting the relative cool overnight to help get the fridge temp down to something reasonable but woke the next morning to find that the van and hence the fridge had lost mains power sometime during the night.
You may also recall a number of limitations of that design:
- If you leave the monitor turned on when travelling, it flashes and buzzes continuously. If you turn it off but forget to turn it on when you are next connect to mains power, it is a waste of space.
- Depending on the internals of the AC-DC adapter you use, there may be a delay before loss of mains is indicated by the monitor (mine takes about 30 seconds).
- When the input signal is not present, LED1 may be dimly lit.
Needless to say, My Mains Monitor 2.0 solves all of these problems.
- It alerts us to the loss of mains rather than the absence of mains. Whilst the lights indicate the presence or absence of mains, the audible alarm is triggered when previously present mains power becomes absent and can be muted by pushing a button. The mute is then disabled the next time that mains is present so that the next loss of mains will again trigger the alarm.
- The delay before loss of mains is indicated by the monitor is reduced to 2-3 seconds.
- There are no erroneous glimmering LEDs.
THe Big Lap Takes a Detour
It was timely that we did our Great Barrier Reef snorkelling trip at Port Douglas when we did because, shortly afterwards, THe Big Lap took an unexpected detour southward.
The day we got back to Cairns from Port Douglas, Helen was diagnosed with a detached retina by the excellent staff at Cairns Base Hospital’s Emergency and Ophthalmology departments. We flew to Brisbane the next day and Helen had surgery that evening.
Fortunately it was detected and repaired when it was “only” partially detached and so far the results are encouraging; unfortunately the recovery is slow and not conducive to travel or significant activity. We will be in and around Brisbane for the next couple of months, expecting to resume THe Big Lap in early September. Meanwhile, with the whale watching season now here, we hope to bring you some blowing and breaching from the lookouts at Byron Bay and Stradbroke Island.
Regards,
-Tim & Helen.
Port Douglas
Arriving from Cape Tribulation late morning, Helen and I discovered it was the final day of a food festival and that today was Seafood Day. Stalls were set up along the marina wharf, operated by local restaurants etc. We were in time for a late lunch of salt & pepper calamari and marinara pizza. For dinner, we bought cooked prawns at the seafood market to end an altogether fishy day.
My Mains Monitor
Problem
Every so often, the mains power circuit breaker in the van trips for no apparent reason. Sometimes, it even trips for a good reason (air-conditioner + hair dryer + microwave oven + etc. >15 amps). Keeping an absorption fridge at temperature in very hot weather can be challenging. We went to bed one night expecting the relative cool overnight to help get the fridge temp down to something reasonable but woke the next morning to find that the van and hence the fridge had lost mains power sometime during the night.
Solution
I built a simple mains power monitor to alert us to mains power failures. It uses old technology: lights and buzzer. Maybe one day its successor will use Twitter (or its successor) to send us the bad news.
In summary, it:
- is powered from the van battery (even when van is connected to mains);
- lights a green LED to show that both battery power and mains power are present;
- takes its “mains on/off” signal from an off-the-shelf AC-DC power adaptor;
- lights a red, flashing LED and sounds a buzzer when mains power is not present.
It has not yet experience a real life mains failure but it is tested regularly: every time we decamp I forget to turn it off before I remove the mains power lead and the monitor always reminds me!
Details
For those interested, here is the circuit I used.
Operation
In essence, it is just two transistor switches in series, each driving an LED, and with the first transistor inverting the input signal for the second transistor.
- The monitor is powered from the van’s 12V system and therefore, importantly, from the van’s 12V battery when mains is not connected. I use a short cable between J2 and one of the van’s “cigarette lighter” sockets.
- An 240V AC to 12V DC adaptor (not shown in schematic above) is plugged into J1. It provides safety isolation of the monitor from the high voltage AC mains supply as well as a conveniently low voltage DC signal that indicates the presence or absence of mains power (note 2).
- The voltage divider R1 & R2 reduces the input signal voltage from 12V to approximately 2V, which saturates T1 without cooking it.
- R3 & R6 are current-limiting resistors for LED1 & LED2, respectively.
- Jumper JP1 is normally shunted; removing the shunt mutes the buzzer.
- Both transistors operate as switches rather than amplifiers, i.e. they are either fully off or fully on (note 4).
- When input signal is present:
- voltage applied to base of T1 is significantly more than 0.7V above its emitter;
- T1 turns fully on and current flows through LED1;
- base of T2 is pulled down to ground by T1;
- with its base voltage less than 0.7V, T2 is fully off and no current flows through LED2 or B1.
- When input signal is not present:
- base voltage of T1 is pulled down by R2 to less than 0.7V above its emitter;
- so, T1 is fully off and no current flows through LED1 (note 3);
-
- T1 is not pulling down the base of T2;
- so, R5 pulls the base of T2 to significantly more than 0.7V above its emitter, turning it fully on;
- With T2 on, current flows through LED2 and B1.
Notes
- If you leave the monitor turned on when travelling, it flashes and buzzes continuously. If you turn it off but forget to turn it on when you are next connect to mains power, it is a waste of space. A future redesign could indicate the loss of mains rather than the absence of mains (i.e. trigger on a falling edge rather than a low level).
- Depending on the internals of the AC-DC adapter you use, there may be a delay before loss of mains is indicated by the monitor (mine takes about 30 seconds). The monitor draws very little current from the adaptor so the smoothing capacitor in the adaptor on the DC side takes that time to discharge to a voltage low enough to trigger the monitor. This is not necessarily a bad thing: it allows deliberate short term disconnection without setting off the alarm.
- When the input signal is not present, LED1 may be dimly lit. T1 is off, but a small amount of current flows from the positive supply (VCC) through LED1, R3, R4 and T2’s base-emitter junction to ground. This could be avoided by a more complex circuit, probably using two more transistors. In practice, with LED2 flashing red and B1 buzzing, a faint, green glimmer in LED1 goes unnoticed.
- For a discussion of transistors operating as switches, I suggest http://www.electronics-tutorials.ws/transistor/tran_4.html.
Parts
- J1 is a socket chosen to suit your AC-DC adaptor, in my case J1 is a 2.1mm socket
- J2 is a socket chosen to suit the cable that you use to connect to 12V battery power: I used a cable with a cigarette lighter plug on one end and a 2.1mm plug on the other so my J2 is also a 2.1mm socket
- my B1 is a 3-30V DC buzzer (Jaycar part AB3458); any noisemaker that works from 12VDC and does not draw more current than the maximum collector current of T2 should do it
- for LED1, I used a green, 5mm LED (Jaycar part ZD0150)
- for LED2, I used a red, flashing, 5mm LED (Jaycar part ZD1785)
- for each of T1 & T2, I used a BC237 because I had them on hand, but any NPN transistor with sufficient collector current to drive an LED plus the chosen buzzer should work (e.g. 2N2222)
- the value of R3 should be chosen to suit your choice of LED1 when used with a 12V supply
- the value of R6 should be chosen to suit your choice of LED2 when used with a 12V supply
- the values of R1 & R2 should be chosen to reduce the input signal voltage to a voltage that will saturate T1 without cooking it. I used a 240V AC to 12V DC power adaptor to generate the input signal because I had one on hand, not because it was 12V. I then choose R1=10K and R2=47K, which reduces that 12V DC by a factor of 10/57 (approximately 1/6), resulting in approximately 2V begin applied to the base of T1 when mains is present (and 0V when it is not)
- the other resistor values (R4 & R5) are not as critical: I settled on them after experimenting with values that minimised the issue noted above whereby LED1 glimmers dimly when LED2 is on; different transistors may require different resistor values for R4 & R5 to minimise this effect;
- for the enclosure I used an ABS plastic box (Jaycar part HB6120)
- the board was cut from a piece of Pre-Punched Experimenter Board (such as Jaycar part HP9550).
Construction
If you read this far, you probably know how to solder all of that onto a board and put it into a box. Here is a picture of the insides of mine before it was screwed together.
Notes
- The white, cylindrical component is the buzzer. At 25mm in diameter it is relatively large; fitting it into the box in a way that avoided the board’s mounting screws was a bit of a squeeze.
- The LEDs are glued using epoxy-resin into holes drilled in the lid of the box.
- Pairs of breakaway header pins on the board and wire pairs with female sockets on one end are used to connect the LEDs and sockets to the board. (I used female-female breadboard wires cut in half.)
- The ink doodling on the board itself should be ignored!
Next Episode
Coming up (hopefully), is a Three-Way Fridge Monitor …
-Tim.
Portable Potable Pumping
We have come to enjoy so-called “free camping” in National Parks and similar locations. Whilst often not free of fees, they are are certainly free of mains electricity and mains water to the van. Some have one tap with drinking water but many do not. Our van’s water tanks are good for 5 days or so if we don’t shower. Beyond that, we have three (3) 20 litre jerry cans with which we drive to the nearest town or location with a publicly accessible drinking water tap where we fill them, then drive back and empty them into the van’s tanks.
We use a hose to fill the jerry cans without removing them from the back of the tug, but emptying them into the van’s tanks is another matter. Whilst 20kg is an acceptable weight for one person to lift, holding it on the angle that gets the water into the tanks without spilling it or dropping the jerry can or pulling off the spout is tricky. Being mindful of this and our ageing backs, a “no lift” solutions is needed.
They key objective was to transfer the water from the jerry cans into the van tanks without removing the jerry cans from the tug. A 12 volt, self-priming pump that tolerated running dry and was not of the submersible variety for less than say $50 was first sought. We tried numerous camping stores, aquarium suppliers and hardware stores but without success. Pumps on offer were not certified for use with drinking water, or were submersible, or both. (A submersible pump is not suitable because you can’t get it down the jerry can’s neck!)
We ended up buying a pressure pump like those used in caravans, but with the lowest rating available: 4 litres per minute. This size of pressure pump is used in camper trailers that have a small tank and one tap, and sells for approximately $100. Whilst this application does not need a pressure-switched pump, that turned out to be the most suitable, albeit expensive, type available.
The pump’s inlet and outlet are barb fittings to suit 10mm hose. We purchased a 6 metre length of clear, beverage-grade plastic hose from the pump supplier for a couple of dollars per metre. You can buy this type of hose at camping or hardware stores but be sure that it is beverage-grade. Cut into one 2 metre length and one of 4 metres, we have one short hose from the jerry can to the pump inlet and the other from the pump outlet to the tank fillers. In the interests of hygiene, we first sterilised the hose with Milton and, when not in use, store it in a zipped plastic carry bag.
The pump’s electrical connectors out-of-the-box are two insulated wires with stripped, bare ends. I crimped four (4) pairs of bullet connectors like so:
- one pair to the bare leads on the pump,
- one pair to the bare cable ends of a 12V “cigarette lighter” plug (e.g. Jaycar PP1995); and
- one pair to each end of a length of insulated twin-core cable.
Our current tug (Ford Territory SZ, 7 seater) has a 12V outlet in the boot compartment so the overall cable did not need to be very long. This arrangement is more complex than necessary and was based on what I had on hand at the time. Simpler solutions include:
- a cigarette lighter plug with a long tail (e.g. Jaycar PP1998) joined with crimped barrel connectors or screw terminals to the pump wires; and
- a cigarette lighter plug with a short tail (e.g. Jaycar PP1995) joined to the pump wires together with an off-the-shelf 12 volt extension lead (e.g. Jaycar PP1992).
As expected from the 4 litre/minute specification, one 20 litre jerry can is emptied in about 5 minutes. To get out the last couple of litres, we found it necessary to tilt the jerry can on a 45 degree angle and manipulate the hose to the bottom corner. There is no manual lifting, and the manual tilting occurs when the jerry can is near empty.
The pump and cables are stored in a sealed plastic box. The hoses are stored in a soft plastic carry bag with zip closures (which originally contained an awning shade).
Hints and Tips
Hygiene
Note that:
- flushing the pump and hose by running some water through them before inserting the outlet hose into the tank filler seems like a good idea;
- the outside of the hoses will come in contact with the water in both the jerry cans and the van tanks and so giving them a clean before each use also makes sense.
- residual water will be left in the hose and pumps regardless of how hard you shake them, so if the most recent use was not recent, consider sterilising them before use.
Pumps
A pump for this purpose should:
- be self-priming (since it will not be gravity fed from the jerry can);
- be able to run dry for a short time without damaging itself;
- have a maximum current demand that is less the 12 volt accessory sockets in your vehicle can supply;
- be certified for use with drinking water.
Note that these pumps:
- are not able to run dry indefinitely, so don’t leave it running unattended whilst it tries to pump out of an empty jerry can;
- are not designed to run continuously, so give the pump a rest every so often (check the specifications for “duty cycle”).
Water Connections
Naturally, your hoses should be sized and adapted to suit your pump’s inlet and outlet. Our pump has 10mm barbed connectors over which we push 10mm tubing. Hose clamps could be used but we have not found them necessary (the pump is only ever run with someone present).
Some larger pumps have a male threaded inlet and/or outlet, which would support a more robust, though complex, fitting. If your pump has a threaded inlet or outlet, it will most likely be of the BSP thread standard for which a variety of adapters are readily available in hardware and plumbing supply stores.
I suggest taking your pump to a self-serve hardware store and playing with their hoses and fittings to invent the simplest, cheapest and most effective arrangement. Use only BSP fittings for a BSP thread or you will suffer leaks and/or use a lot of teflon tape. BSP connections should not need teflon tape (one or both sides of a join has a tapering diameter, which gives a water-tight joint). Alternatively, take the pump to a plumbing supply store, tell them your application and they should easily do the same. If you are buying the pump from a plumbing supplier and describe your application, they should be able to supply all the “wet” parts required for an optimal end-to-end solution.
Electrical Connections
If using crimped spade or bullet connectors, remember that a connector supplying +12V should be female to avoid shorts and blown fuses (or worse) when it accidentally touches a metal part of the vehicle. (Hence the connector receiving +12 volts is male.) I use opposite genders for the earth (a.k.a. ground or 0 volts) connectors. This prevents accidentally connecting one cable to the other with polarities reversed and hence reverse polarity being applied to the pump motor, though it does allow the 0V supply male to be inserted into the +12V supply female, which is also not good.
If using connectors (e.g. screw terminals) that leave any live +12V points exposed, wrap them with electrical tape.
If using insulated crimp connectors for the first time, it helps to know that the colour of the insulation on this type of connector corresponds to the diameter of the copper in the wire to be crimped (red is smaller than blue is smaller than yellow) rather than to the size of the spade, bullet, etc. The spades and bullets themselves are the same size, for example, a red male bullet fits a blue female bullet.
Soldering of these electrical connections is not recommended unless care is also given to the “mechanical connection”. When the ends of two flexible wires are soldered together, the two points at which the flexible copper meets the less flexible solder are subject to extra stress when the wires flex and will eventually break.
Some cigarette lighter plugs have an internal fuse; this can cause confusion if it blows and you don’t know it is there.
If you are not confident in choosing appropriate connectors and cables to suit the current draw of your pump, and/or in making reliable connections, you should use off-the-shelf components or engage an auto-electrician.
Water Containers
Given that the jerry cans no longer leave the tug’s boot, at least not when full, they do not need to be limited to a gross weight that can be manually lifted. You might consider using fewer but larger and more efficiently sized and shaped containers. Your choice!
Water Sources
For accessible drinking water taps in country towns we have found the following locations fruitful:
- around the back of community halls;
- at fish cleaning stations next to boat ramps;
- RV Friendly Towns – the conditions of “RV Friendly Town” certification by CMCA mandate access to of potable water and encourage the existence of an Information Centre (e.g. to tell you where that water is).
We always remove any existing hose from the tap, run some water to flush the tap, and connect our own hose to fill the jerry cans (being sure, of course, to replace the pre-existing hose before leaving!).
Estimating the length of the two hoses can be fraught. Consider where the pump will be located when operating to help decide the length of the inlet hose; don’t forget the metre or so needed to get to the bottom of the jerry can. The outlet hose length depends on how close to the tank fillers you expect to be able to get the vehicle; think about how to route and secure it so that it doesn’t fall out of the tank filler and doesn’t trail in the dirt.
Postscript
A couple of weeks after buying and setting up the small pump described above, we had to replace the larger (11 litres/minute) pump installed in the van. Whilst the old pump worked OK in the forward direction, it developed a slight flow in the reverse direction. Because the van is plumbed in a way that relies solely on the pump to prevent mains water entering the tanks, this resulted in the tanks overflowing when mains water was used.
As a result, we now have a spare 11 litres/minute pump that would be quite suitable, and indeed quite fast, for transferring water from the jerry cans into the tanks!