Tuesday, 18 September 2012

Something Alarming! - Part 1

The official Pike season is only a few weeks away so my thoughts have drifted in the direction of the toothy ones in preparation.
For a couple of years I've been using bobbins fastened to the back rest as drop back indicators but I've been thinking about an electronic version of the same. I've had a quick look around the Internet but with cash being as bit short I couldn't find anything cheap except for the 999 alarm from Zandavan. It works on the principle of a tilt switch as the break in a simple circuit, when the bobbin drops the tilt switch makes contact, completes the circuit and a siren sounds until it's switched off, simple.
(isn't it always the best)
I've always dabbled in electronics, taking things apart and re-soldering to fix something that was broken or finding a way for modifying a circuit to do another job.
I thought I'd have a go at making my own electronic drop back indicator. I had a good grasp of how this circuit works and set about building one, A few simple parts were sorted from my electronics box and purchased from Maplin. After a bit of planning and testing the circuit was ready and put into a project box, I doubled up parts of the circuit so I was able to use two bobbins off the same sounder and save on parts, I ended up just using the one battery and one buzzer.

The cobbled alarm, version one.
The bobbins were the hardest to work out as I didn't want them to be fastened permanently to the box, this would cause a weak point in the cable where it exits the case and could cause problems later should the cable fail at this point, I opted for a connection more commonly found on the back of your hifi, a phono connection. The tilt switch was housed in a section of plastic from a pen with some old line clips glued into the end.

Hi fidelity connections!

Now, where did I put that pen?
I used a couple of Sharon's hair elastics to temporarily fasten the alarm to a bank stick for testing down the canal, it seemed to work fine although I think the alarm could be mounted slightly higher. With regards to detecting bites, they work a treat.

Fastened with hair elastics.
The Zed's I had nibbling the baits gave the bobbins a good shake and after a little adjustment they detached from the line and dropped to the floor with the alarm screaming.

The smaller of the alarm testers.
I missed a couple of takes adjusting the clips and concentrating on the alarms performance and not the fish.
Slightly bigger but not much.
I'm thinking of adding a vibration sensor to the bobbin with an LED that lights up when the bobbin is moved however the wind factor could make this a problem.

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