Sunday, April 22, 2012

Not for the faint hearted

P1060019 (1024x944)

Blimey, what a tangle.  My latest project for a Herbie gadget is much less complicated than it looks.  This is just a first prototype. That little black chip has 18 things connected to it, hence the tangle, but all it really amounts to is four switches to turn on the four green LEDs when those five  loose dangly wires pass a small current.  The danglies  are all submerged in water.  The dangly on the right connects to the plus side of a little pack of four AA batteries.  The others pick up the current through the water and as they do, the switch lights up the lights.  Dipping  the wires in a jug of water it appears to work.

If I ever get it finished it might look more like this

water gauge

Its a water tank gauge.  The wires will be cut to lengths so as to contact when the tank is 1/4 full, 1/2 full and so on and the little lights will come on accordingly. Its really an electronic dip stick.

The hard bit comes in trying to get a neat circuit layout on a bit of copper strip board.  I’m thinking of attaching the danglies to a bit of thin plastic pipe to keep them straight, it only needs to be about half an inch diameter.  Then I have to decide whether just to drop it in via the filler cap, or permanently fix it through a hole drilled in the top of the tank. The latter would be better as I wouldn’t then have to withdraw it all when we are filling the tank.

I imagine it will end up costing about £2.50 for the bits.  Add labour costs at the minimum wage and the end cost will be about £500!!  I am a slow worker.

Still, it keeps me off the streetsSmile


Halfie said...

I like it! I suppose with the minute currents involved the effect of electrolysis will be negligible. Any chance of publishing the circuit diagram?

Will you poke it down the filler, or fix it inside the tank?

One strange thing about Jubilee is that the water tank has, apparently, a plastic liner. The access is via a small (6" square) plate bolted to the well deck.

Anonymous said...

I'm ignoring the strange spaghetti above....
Are you two thinking of going along to the Little Venice cavalcade this year? If so, be good to meet for a pint.

Neil Corbett said...

Halfie - I'll try and tidy one up

Carrie - providing we're not out boating (we're finding it very difficult to fit in much boating lately so will grab a chance when we can), we'd love to meet up at LV. We'll let you know.

Roger Smith said...

Some thoughts on your depth gauge, seriousness may vary.
Firstly it might be a good idea to bend the bare ends away from the carrying tube otherwise the damp on it could give a false reading.
Secondly if your water is pure enough it isn't that good a conductor so your gauge might work better if you add salt to the tank when you top up.
Third thought you could use a variation of this as a depth gauge, tow the current feed wire beneath Herbie on the bottom of the cut then mount the dipstick on a pole from the bow (like a bowsprit) then as the depth changes you will get a warning.