Auto anchor light

[alahol2]

Many years ago (20?) I made an automatic anchor light from a circuit diagram which, I think, was given in one of the mags. It fitted into a plastic spice jar and used an ordinary torch bulb. It's still going to this day but has always been a bit 'dim'. I would like to make another but utilising a high powered LED and one of the reflectors from a cheapo LED lantern. I've searched for a suitable circuit diagram but not found one that exactly matches what I'm trying to do and I am not well enough up on electronics to modify one. Anyone know where I can get a circuit diagram from?

 

[beserksail]

Buy a circuit diagram from Maplin [ complete with components ] for about £7.00. Ref QP97F.

 

[noelex]

Bebi make a few comercial units. Cheap enough to make it not worth DIY

 

[Salty John]

Here's one a friend of mine used to make 'jamjar' lights to sell to cruising boats in the Florida Keys, many years ago. Maybe adaptable to a regulated LED cluster. Hardly seems worth the effort and component cost when you can get a Salty John automatic LED anchor light for under £40, (commercial interest alert!), but I do appreciate that many derive pleasure from the project itself rather than any monetary saving.

R1 = 10 k-ohm trim pot
CS = phototresistor
Q = 2n2222 npn transistor
Relay = 12v 320ohm 10amp SPDT
SW = Switch, centre off
LED = Red, low current to indicate when light is on.

There are probably simpler versions available; all these bits were available at the time from Radio Shack in the USA. I would think equivalents are available at Maplins.

 

[noelex]

Becarful with some circuits as the power consumption can be more than the saving.

 

[mollyoxford]

anybody know of a battery powered version? The staysail halyard is a long way from any 12 socket on my boat!

 

[TRUNDLETRUC]

Anchor light

With Solar cell LED garden lights selling so cheaply why go to the bother of making a circuit up when you can fix one of these somewhere high on the boat? Sailing as we do, in sunny Greece it usually lasts all night before it runs out of power.

 

[mollyoxford]

I haven't yet found a solar LED garden light that isn't too big or the wrong shape etc... Though that's probably me

 

[RivalRedwing]

anybody know of a battery powered version? The staysail halyard is a long way from any 12 socket on my boat!

sounds like a Salty John commercial opportunity if fitted with an LED bulb

 

[Salty John]

We used to offer a 6v battery powered anchor light which we fitted with an LED 'bulb' but it was discontinued by the US manufacturer.
Originally marketed by Guest many years ago, they had a good reputation because of very solid, waterproof construction. You still find them on eBay from time to time. Quite expensive but worked well.
You can get a 12v 2.2 ah battery from Maplins for about £20 and a charger for about the same price. You can then plug your anchor light into that, if you devise a way of waterproofing it - Tupperware box?

 

[eddie2000]

You could always use a water resistant LED torch, the type which has a pull-out end so the light goes out sideways all round. Mine also has some down light which illuminates the boat a bit so passers by can see the yacht. That's what I use for most mooring situation, just hang it on the forestay. Consumption negligible and probably the cheapest option.
I would probably use something brighter if anchoring near large ship routes though.
Eddie

 

[alahol2]

Thanks all.
Both the circuits suggested (Salty Johns and Maplins) use a relay which, I suspect, would negate the use of a current saving LED bulb. The garden lights are rather large and need to be on deck during the day in order to charge up. The battery torch/lanterns need to have good batteries.
The one I made was VERY simple, probably cost less than a quid (admittedly 20+ years ago) and fitted into a 35mm film canister. So I reckon I could make one now for less than a fiver if I could get the right circuit. Perhaps I'll see if I can dismantle the old one and copy the circuit.

 

[RAI]

Before I fitted a masthead anchor light with LED bulb, I hoisted a slightly modified 12V florescent inspection lamp (I took out the reflector and fitted a long wire). It gave off an indecent amount of light but used very little current. Running out and collecting the wire was a drag but I still retain it for situations where I feel vulnerable to late comers.

 

[vyv_cox]

With Solar cell LED garden lights selling so cheaply why go to the bother of making a circuit up when you can fix one of these somewhere high on the boat? Sailing as we do, in sunny Greece it usually lasts all night before it runs out of power.

Don't fool yourself. Solar powered garden lights give a tiny fraction of the light required for a reasonable anchor light. You are very lucky to see the tiny glimmer these things give at 50 metres, never mind a mile. Especially mounting them high up - do you think Greek fishermen ever look upwards for anchor lights?

 

[William_H]

Anchor light

I think those solar garden lights are amazing but in high ambient light situations they may be too dim.
So the alternative is to run the light off 12v. If it is to be LED then either use a LED replacement bulb set up for 12v or use 4 leds (idividual diodes) in series with a current limiting resistor. You can use one diode but you might as well use 4 as the current from the battery is the same.
The problem with the LEDs is that they are inherently directional in light output so for an anchor light they would need to be wide angle as possible (some are wider than others) and arrayed around in a circle. You might need 8 diodes ie 2 lots of 4 off 12v. Alternatively the garden solar lights use a clever light diffuser so the led diode (bulb) faces downward and the diffuser directs the light out at rightangles and 360degree azimuth. So you could use the diffuser from one with 4 bulbs facing downward.
In the case of the op with an existing light and daylight switch it should be ok to replace the incandescent bulb with LED either as a replacement bulb or a bunch of 4 or 8 individual diodes.
You need to be satisfied that the 12v battery will be about 12.5 volts actual voltage and the anchor light won't be used with engine running charging the battery (or charger on). If you want to use individual bulbs and be able to cope with battery on charge then just use 3 in series with a resistor suitable for 14vsupply.
The series resistor is calculated from adding the voltage of the series diodes usually about 2.4 v so 4 diodes gives 9.6v subtract that from the supply voltage ie 12.5 volts gives 2.9 volts to be dropped at the current required by the leds typically 25 ma R+ E/I 2.9 divided by .025(amps) gives a resistance of aprox 100 ohms. You need to get the actual current and voltage from the data sheet of the diode you buy.

I have to appologise about the naming problem. Originally an LED was a tiny bulb with 2 wires out the bottom and a magnifying lens on top. about 5mm in diameter. Now these bulbs ( diodes) are sold as a replacement globe or bulb with 12v control circuitry built in and they are called LED bulbs and of course light fittings are sold as LED lights so it is all confusing. the individual diode bulbs can be bought from electronic suppliers for a few pence though I have found that buying a string of white christmas lights provides many bulbs very cheaply. They are wored as goups in series so cut out one group about 9 bulbs leaves the rest working OK. olewill rattling on again.....

 

[zzjfawce]

I can vouch for the Bebi lights. I hang one from my backstay and it is the brightest light amongst all the boats moored in our area (local regs dictate the use of an anchor light even when on designated moorings). I would be doubtful of the garden lights fulfilling the Colregs criteria for visibility because they seem quite dim.

The Bebi lights are now marketed with a photosensor but when I bought mine that wasn't available so I bought a light sensing electronics components kit - actually I had to buy several because my soldering skills weren't what they were at school. There are at least three main circuit designs and one of the online companies, AnyKits I think, will sell you a kit containing all three versions so you can make them all and compare their characteristics (but only if your name is Norman Nomates ).

When I finally did make one that worked (it activates a relay), I connected a 12 V input and directed the output to the anchor light, embedded everything in a waterproof box with epoxy resin (and positioned the sensor in a little hole in the side of the box, then sealed over with resin and clear nail varnish which has not degraded yet). A fair bit of effort and I would now def go for the auto Bebi version.

 

[alahol2]

Finally got round to dismantling the old anchor light and copying the circuit diagram which I reproduce here.
I've since made another one using a cheap battery 8 LED lantern (£1.95) + components (about £5.00). Remove the battery carrier and insert the circuit in its place with the photoresistor stuck on the side of the lamp. It works fine and is far more visible than the old one which was only about 3 watts. The new lamp draws about 200mA when on and microAmps during the day.
Just out of interest, if anyone can explain in simple language how it works I would be grateful... It was an interesting project.

 

[Silent Lady]

How it Works

The top transistor is the switch that turns the light on / off . It provides a path to ground for the bulb .

The lower transistor is the control for the other and decides at which point it should switch on and off .

This control is achieved by the resistance changing in the photo cell . The variable resistor is used to set the point that the lower transistor should turn the upper one on .

A transistor will switch on fully when its base voltage is 0.7 of a volt . So what you are trying to do with the photo cell and variable resistor is set up a point when dependant on light the voltage to the base of the transistor is 0.7 volts . This will be as it gets dark . As it gets darker the voltage may well increase past 0.7 volts . As it gets lighter then the voltage at the base of the transistor will fall as it drops below 0.7 volts the transistor will turn off . This then switches the other transistor off . The path to negative for the bulb is broken and the light goes out .

Why two transistors . Well a transistor will start to conduct slowly at first so you would see the bulb start to glow and then start to fade rather than just switch on / off

Hope that helps . .

 

[prv]

I have (but have not yet used) the autosensing Bebi light. Seems like a good piece of kit, is very bright and extremely compact, but I'm not sure it's as cheap as a previous post implied, once you've taken import taxes and fees into account.

Pete

 

[alahol2]

IAN13 very many thanks for that explanation. You anticipated my 2 main queries which were 'Why 2 transistors?' and what voltage switches the transistor on.