For about half the price of a basic, shop-bought buzzer, anyone with a rudimentary understanding of circuitry and a well stocked tool-box can make his own sight-and-sound indicator the antenna trigger and should sup-port a piece of silver paper between the first and second ring . When pulled, it moves the antenna, so closing the relay con-tacts. This makes the diode glow and speaker sound.
A daunting list?
Many anglers feel unable to make an electric bite indicator as they are baffled by unfamiliar components and all the symbols used to identify them. But the indicator described here is easy to make. The components are shown as they really look, not as obscure symbols.
I call the indicator the ‘Minitector Monitor’. It is a self-contained unit which screws on to a standard bankstick without additional wires or boxes on the bankside. Diagram A is a general view with the front removed to reveal the insides. It is used as a top rod rest, with the butt of the rod supported by a second, taller rest. The line is taken round l10in spacing Vero board; 20 or 22 SWG piano wire (obtainable from model shops); a relay contact set comprising six Paxolin insulation pieces, a centre insultation tube, two relay blades, and two 6BA bolts, washers and nuts; a plastic case with a screwed-on top; a PP3 battery and connector; a small piece of strong card; two 4BA cheesehead screws plus two sizes of plastic sleeving to fit their threads and heads; a fin BSF cadmium-plated bolt, nut and washers; a small piece of foam block; a small piece of metal mesh or nylon cloth; a piece of fine plastic tubing—about l10in bore; plastic-covered fence wire of 316in diameter, and some red and black fine electric wire.
You will need the following tools: a miniature soldering iron and cored solder; a hand or power drill and a small selection of drill bits; a fin BSF and a 6in BA spanner; a 4BA thread tap; a smaller round file; a small hacksaw; a pair of pliers; Vaseline or MS4 silicone grease; fine emery paper; Evostick or similar adhesive and an epoxy resin adhesive such as Araldite; insulation tape or Copydex adhesive; and some paint.
Do not be put off by the length of this list. Assuming you already have most of the tools, such as the soldering iron, drill and file, the rest of the components can be purchased for about £4.50. Most cannot be found in High Street electrical shops—the sort that sell £600 colour TV sets—but can be obtained easily from shops specializing in parts for radio builders. The staff are generally helpful and knowledgeable.
Room to spare
The case needs special mention. Radio shops sell many sizes of case with lids attached by cadmium-plated screws. Buy one bigger than strictly necessary—about 4in long, 2An wide, and l?in deep is fine.
With plenty of space, there is less risk of shorting out the components, or of the antenna system fouling another part. If you are confident that you can fit the parts into a smaller case, modify the details.
The first thing to do is make the electrical circuit [see Diagram B). Vero board is a plastic laminate with holes drilled in it. Underneath the holes are thin strips of copper foil which conduct electricity. The strips of copper can be broken at any hole with a small drill. In this design, only one hole needs drilling.
Wiring up the Vero board
Cut a piece of Vero board 14 holes by 5, with five strips of copper running along its length. Now, looking at Diagram 3, locate hole W8 and push a bit of wire through it from the top (non-copper) side so that you can identify it when you turn the board over to cut the copper strip. Then drill the copper away from this hole by twisting a drill bit back and forth between your fingers. Make sure all the copper has gone—use a magnifying glass if necessary.
All the electrical components will have little wires protruding from them. These are used to fit them into place. Start from the left-hand side of the board, with the copper strips underneath. Bend the wires down on resistor Rl and insert one into hole Wl, the other into hole Zl. Using a little tag—which should face upwards—on its side to locate the wires, push the E wire of transistor Tl into hole V3, the B wire into W2, and the C wire into hole X3. Push the capacitor wires into holes W6 and W10.
Transistor T2 is fitted in the same way as Tl, except that the little tag faces downwards. Fit wire C into Wll, B into X12, and E into Zll. Finally, fit the resistor R2 into holes V13 and Y13. When properly fitted, all these components should be soldered into place.
Next take two pieces of electrical wire, each about 5in long, and solder them into holes V14 and W14. Solder the other ends of the wires to the two solder tags on the speaker. Solder similar lengths of wire into holes Y14 and Z14. Now cut two pieces of plastic sleeving long enough to insulate the legs of the light diode, and slide one down each of the wires.
Then solder the legs of the diode to the wires, and slide the sleeving back up the wires to cover the bare diode legs. Finally solder a short piece of wire into hole VI and bare its loose end. This will connect to the antenna contacts when the circuit is eventually fitted into the case.
Test and solder
You can now connect the battery to test the circuit. PP3 battery connec-tors already have red (positive) and black (negative) wires attached, so you do not need to add these. Solder the other end of the black wire into hole Z2. Then bare the end of the red wire, fit the battery connector on to the battery, and touch the bare end onto the bare end of the wire soldered onto VI. The speaker should emit a low-frequency sound of about 300 cycles per second and the diode should light. If the speaker 4 sounds but the diode does not light, you have got the diode the wrong way round. Just unsolder the leads at Y14 and Z14 and reverse them.
Case and rod rest
When the circuit is built and tested, you can press on with the case and its attachments. Start with the rod rest. This is made from a piece of plastic-covered fence wire about 18in long. Bend it to form a narrow ‘U’. Then wrap a bit of rag or card- s board round the wire to protect it | and squeeze the bend with pliers to 2 make it really tight. The ‘U’ is the £ line slot of the finished rod rest. As £ described, the indicator is suitable for lines of 5-10 lb, but by adjusting the relative positions of the line slot and antenna trigger it can be modified to suit lines as fine as lV&lb or as heavy as 30lb. But do not attempt to span this range with just one indicator.
When the line slot has been made, bend the ends of the ‘U’ back on themselves to make the ‘M’ shape shown in Diagram A. Cut the surplus off each side, but leave %in to enter the holes in the case top.
Drill four holes on the right-hand side (looking from the front). Holes 6 and 7 are for the screws which hold the antenna relay blades. (The positions shown are for the offset contact screws; if you use a different type, vary the holes accordingly.) Holes 5 and 8 are for the adjusting screws. Tap these with the 4BA tap so that the screws can be screwed into the case. If you do not have a 4-BA tap, drill the holes slightly small and screw in the screws. They fy will cut their own threads in the plastic.
The eighth hole should be drilled in the centre of the base to take the fin BSF bolt which holds the case to the bankstick.
The next drilling job is to make the speaker grill in front of the case. You can either drill a lot of small holes or make one large hole (slightly smaller than the speaker) and fit a fine metal mesh over it. To make a large hole, draw a circle on the case and then drill a series of small holes around its inside circumference. If the holes are close enough, the centre of the circle will fall out and the circle can then be filed down to make a perfect shape. Bevel the lower edge so that it slopes down and out to help any water run away.
Cover the holes
If you decide on several small holes, drill them in a regular pattern from the outside, with the drill pointing slightly upwards. Then glue a piece of fine nylon or other synthetic material on the inside of the case to cover the holes.
The next task is to fit the relay contacts to the case. The parts of 12 these are shown in Diagram A. Put a thin coat of MS4 silicone grease or Vaseline on the insulation plates, and roughen the inner surface of the inner relay blade with fine emery paper. Then push the two 6BA bolts through the holes in the case from the outside.
When this is done, push a centre insulation tube on to each bolt. Then push on to both bolts two insulation plates, the outer relay blade, two more insulation plates, the inner relay blade, and finally two more in-sulation plates. Add a nut to each bolt and tighten with a spanner.
The next job is to make the battery holder. Cut a piece of strong card, the same width as the case, and bend it into a flat ‘U just big enough to hold the battery and its connector. Glue it into place in the base of the case. A piece of foam stuck on to the case front opposite the battery will also help to hold the battery firmly in position.
The case is now ready for painting. You can paint it by hand or use an aerosol spray. I use one coat of primer and three coats of finish to give a good result. Screw the case on to the bankstick to make it easier to hold while painting. Paint the piano wire for the antenna. Left un-painted, it will rust.
When the paint has dried, fit the antenna wire. You can either Araldite it in place, or solder it. Roughen the end of the antenna wire and the inner relay blade with emery paper and pre-tin them if soldering. Then lay the indicator on its side—relay contacts at the bottom—feed one end of the antenna wire through the waterlock tube and rest the other end on the inner relay blade. Then, without touching it, solder or Araldite the wire into place. When finished, the antenna assembly should make a ringing noise when the case is tapped. If it does not, tweak the wire until it does. Finally, clean the silver contacts with fine emery paper.
When you are satisfied that the antenna system is working correctly, drill a £in diameter hole in the back, just below the antenna trigger and the waterlock tube. Then cut a piece of thin metal into a very shallow ‘V about lin long by £in wide. Bend it slightly at the bottom of the ‘V which will make it tilt. Now Araldite it to the back of the case just below the hole, tilting slightly backwards. When the in-dicator is in use, the ‘V acts as a baffle. Any water which enters through the waterlock collects in it and runs out of the hole.
You can now fit the electronics into the case. Solder the red wire from the battery connector to the inner relay blade, and the wire from hole VI on the circuit board to the other relay blade. Stick the diode, the circuit, and the speaker lightly into place with Evostik or a similar adhesive. Coil any loose wires towards the lower left-hand side away from the antenna system.
Apart from sealing the case, the only job that remains is fitting the adjustment screws. Cover each screw with two plastic sleeves to form a ‘shoulder’ and a larger head . The sleeves prevent the bolts being screwed too far in, thus damaging the contacts, and also makes turning the small bolts much less fiddly.
Test it first
Before sealing the case, test the in-dicator to see if everything works properly. Fit the battery connector, tighten the upper (contact gap) screw until the relay blades are just open. Then tweak the antenna. The diode should now light up and the speaker sound.
All you need to do now is fit the front, and the indicator is finished. The joint between the front and the rest of the case needs to be waterproofed. You can run a strip of plastic insulation tape round the joint, but a better method is to apply Copydex round the lid. Screw the lid into place and wipe surplus adhesive away before it sets. Copydex does not adhere to plastic, it simply seals the joint. As the bat- tery will last between 1 and 2 years with average use, this method is a neat and perfectly acceptable way of sealing the case.
When you are not using the in-dicator, the adjustment screws should be slackened off. They can be tightened to suit conditions at the bankside. To adjust them properly, place the rod in the two rests and connect the line round the antenna trigger; screw the top screw in until the indicator sounds continuously; adjust the bottom screw until the sound stops; readjust the top screw until the indicator sounds again, then ease-off a fraction to stop the sound. Finally, test the indicator sensitivity by tweaking the line in front of the antenna. With practice, it takes only a few seconds to follow this routine. If wind or drag increase, making the indicator sound, simply readjust the screws.
The waterlock, the baffle plate and the foam speaker backing— which soaks up water—are all Minitector developments which pre-vent the circuitry becoming wet and unreliable. Your home-made, and sensibly priced, indicator should provide you with many years of trouble-free service.