GB2250901A - Bite indicator - Google Patents

Abstract

A bite indicator composes a sensing member (10) in frictional contact with a fishing line and operative to vibrate in response to line movement, a circuit for producing an electrical signal in response to vibration of the sensing member, and a sound generator for producing an audible sound in response to the latter electrical signal. In order to reduce the risk of positive feedback setting up uncontrolled oscillation, the sound generated in response to sensing of line movement is intermittent under all operating conditions, and means (FET) are provided for inhibiting the operation of the circuit responsive to vibration of the sensing member at any instant during which sound is produced by the sound generator. <IMAGE>

Description

Title Bite Indicator Field of the invention The present invention relates to a bite indicator for sensing the movement of a fishing line.

Backqround of the invention It is known to provide a bite indicator in a fishing rod support, in which the fishing line is arranged to pass over a pulley which rotates as line is drawn out. The rotation of the pulley is sensed magnetically, or by other means, to produce an audible signal. In certain types of angling, for example when fishing for carp, it may take a considerable length of time for fish to take the bait. Anglers therefore use several rods-at the same time to improve their chances of success and a bite indicator is of value to such anglers in that it enables several rods to be watched at the same time.

There has also been proposed a bite indicator which can sense line movement without the use of a pulley. A sensing member is mounted for direct contact with a fishing line and a circuit generates an electrical signal in response to vibration of the member to activate a sound generator, friction between the member and the fishing line serving to cause the sensing member to vibrate in response to line movement.

A problem is encountered with the latter form of line sensor if the loudspeaker serving to produce a sound to alert the user to the line movement is mounted in the same casing as the sensing member because positive feedback takes place with the sound generator setting up vibrations in the line movement sensing member-.

bect of the invention The invention seeks to provide a bite indicator of the type which senses line movement by setting up vibrations in a sensing member but which is not affected by posltrnve feedback from the sound generator.

Summary of the invention According to the present invention, there is provide a bite indicator comprising a sensing member in frictional contact with a fishing line and operative to vibrate in response to line movement, a circuit for producing an electrical signal in response to vibration of the sensing member, and a sound generator- for producing an audible sound in response to the latter electrical signal, characterised in that the sound generated in response to sensing of line movement is intermittent under all operating conditions, and means are provided for inhibiting the operation of the circuit responsive to vibration of the sensing member at any instant during which sound is produced by the sound generator.

Preferably the sensing member includes a piezaeleetric crystal whereby an alternating signal is produced when the sensing member vibrates.

Conveniently, the circuit responsive to vibration of the sensing member comprises a voltage controlled oscillator operative, when the level of the output signal from the piezoelectric crystal exceeds a predetermined threshold, to produce a pulsed signal having a frequency related to the amplitude of vibration of the sensing member The pulsed signal at the output of the voltage controlled oscillator is used to enable and disable the sound generator so that the repetition frequency of the eiritted -sound-indicates the speed of line movement.

Advantageously, the voltage controlled os,, is adjustable so that the frequency of the pulsed signal may be varied. This allows the user to set the repetition frequency to suit the thickness and tension of the line and the anticipated speed of line movement.

The means for inhibiting the operation of the voltage controlled oscillator conveniently comprises a sampling circuit arranged between the piezoelectric crystal and the input of the voltage controlled oscillator which allows signals to pass to the voltage controlled oscillator only when the voltage controlled oscillator output signal disables the sound generator.

It has been found that even after the sound generator has been disabled, resonances set up in the casing can cause accidental retriggering of the voltage controlled oscillator and for this reason is it desirable to include a delay circuit to prolong the time during which signals are inhibited by the sampling circuit from reaching the voltage controlled oscillator.

In certain prior art bite indicators, when the line moved faster than a certain rate, the sound generator would operate continuously to produce an alarm tone. In the present invention, an alarm cannot be produced continuously as this would not allow any time to sense line movement. In order to provide the equivalent of an alarm tone, it is desirable to employ a two tone sound generator and to produce an alternating tone, or warbling sound when the speed of line movement or the repetition frequency of the voltage controlled oscillator exceeds a preset threshold.

In order to enable the sensitivity of the bite indicator to be adjusted, it is advantageous to provide at least one variable gain amplifier to amplify the output of the piezoelectric crystal.

tehX line speed varies the amplitude of vibration of the piezoelectric crystal and it is therefore the amplitude of the AC component of the output signal that is to be sensed. The amplifier may therefore be an AC amplifier followed by a detector or if desired a DC amplifier can be used to amplify only one half of the waveform and act as a combined amplifier and detector.

Brief descriPtion of the drawing The invention will now be described further, by way of example, with reference to the accompanying drawing which is a circuit diagram of a bite indicator in accordance with the invention.

Description of the preferred embodiment In the drawing, the usual symbols and reference numeral prefixes have been used to identify the circuit elements.

In particular the prefix R indicates a resistor, 72 a variable resistor, C a capacitor, D a diode, IC an integrated circuit, TR a transistor, G a gate, L an inductor, LED a light emitting diode, FET a field effect transistor, LS a loudspeaker, SW a switch and SK a socket.

A detailed description of the connections between the circuit elements, beyond what is illustrated in the circuit diagram, is not therefore deemed necessary and the description below will concentrate on the function served by the various parts of the circuit.

Reference numeral 10 designates a piezoelectric crystal 10 mounted in a casing (not shown) which is mounted on a bank stick and has a V-shaped recess for supporting a fishing rod. The line on the fishing rod passes over the end of an elongate stylus secured to the crystal 10. The stylus extends at right angles to the line so that it vibrates when the line moves over it and causes the piezoelectric crystal to emit.an AC -signal.. - R1, R2, IC1, D1, C1 and VR1 form a variable gain AC amplifier for amplifying the output of the crystal 10.

VR1 allows fine tuning of the sensitivity. R3, R4, R5, SW1 and IC2 form a switchable gain amplifier. SW1 allows coarser adjustment of sensitivity for example to allow for different thicknesses of fishing line. The integrated circuits IC1 and IC2 may be an TLC 271.

Following amplification, the signal is half wave rectified by diode D2 and partly smoothed by R6 and C2 before being applied via a sample and hold circuit formed of the FET, R7 and C3 to the input of 1C3. IC3, which may be a 4046, forms, together with R8, C9, R9 and VR2, a low frequency voltage controlled oscillator which produces output pulses having a frequency which depends on the DC voltage across C3 and the setting of VR2. The latter allows the user to set the frequency to pulsate at whichever rate is preferred under the conditions of use. This pulsating signal is used to enable and disable a tone generator so that a sound is produced having the same repetition rate as the output of the voltage controlled oscillator.

The tone generator is an oscillator built around the gate G3 and comprising C8, R14, R15 and VR3. The variable resistor allows the pitch of the tone to be varied by the user so that individual bite detectors can be audibly distinguished from one another. The output from G3 is applied via G5, acting as an inverter, and volume control VR4 to the power amplifier comprising TR2, R17, L1 and D8.

This power amplifier drives the loudspeaker LS which produces the audible sound to alert the user of line movement. Additionally, the output of G5 is applied to a second power amplifier TR1, R18 which can drive a remote loudspeaker plugged into the socket SK.

Assuming the FET is conductive, whenever the line moves an AC signal is produced in the crystal 10. This signal is amplified and rectified to-develop a DC voltage across C3.

If this voltage fez a predetermined value, the voltage controlled oscillator IC3 begins to operate and each purse from it enable gate G3 so that the tone generator codes into operation and produces a signal L for powering the loudspeaker LS.

Difficulty arises in that, if the loudspeaker is mounted in the same casing as the crystal 10, the latter now starts to generate a signal induced by loudspeaker vibration rather than line movement and the circuit includes additional components to reduce the risk of such positive feedback.

The principle on which the circuit operates is that the FET is rendered non-conductive whenever the tone generator is operating. To this end, the output of IC3 is applied via a delay circuit D3, C4 and R10 and an inverter G1 to the gate of the FET. The delay circuit is included to allow for reverberations in the casing after the loudspeaker has ceased to operate.

The output of IC3 is also applied via C6 to G2, which together with R11 C5 and D5 forms a latching circuit. When the output of G2 is high, the LED emits light and continues to do so for some time, typically 10 to 20 seconds, after voltage controlled oscillator has ceased to operate. The need for this is to provide the user with a lasting indication of which bite indicator sensed line movement, if several lines are in use at the same time.

The circuit consisting of IC4, IC5 (parts of a 4013), R12, R13, D6, D7 and C7 is a threshold frequency detector having an output line connected to G4. The latter is arranged in the feedback circuit of the tone generator gate G3 and when conductive connects R16 in parallel with R15 to vary the pitch of the output signal of the tone generator.

The threshold frequency detector receives as its clock signal the output from IC3 which is used to enable the tone generator. It also receives a reset signal from the output of G1 via diode D4. Below a frequency set by R12, C7, the output applied to G4 is off. Above that frequency, G4 receives a pulsating signal and G4 is switched on and off in successive cycles of the output of the voltage controlled oscillator. Consequently, when the line speed reaches a certain level, the single tone from the speaker changes to an alternating warble and provides an alarm indication to alert the user to rapid line movement.

It will be clear that various modifications can be made to the circuit without departing from the scope of the invention as set out in the appended claims. For example, the sensing of line movement can be rendered inoperative while a sound is being generated by shorting the crystal to ground before the signal is amplified. Further, the means for detecting the level AC signal induced in the crystal need not be the voltage controlled oscillator but may be, for example, a Schmitt trigger. The alarm condition can be set up by an analogue technique in which the DC level across C3 is monitored rather than by the digital technique described for monitoring the output frequency of the voltage controlled oscillator. Numerous other modifications may be made in the detail of the construction of the amplifiers and the tone generator and the voltage controlled oscillator.

Claims (9)

1. A bite indicator comprising a sensing member in frictional contact with a fishing line and operative to vibrate in response to line movement, a circuit for producing an electrical signal in response to vibration of the sensing member, and a sound generator for producing an audible sound in response to the latter electrical signal, characterised in that the sound generated in response to sensing of line movement is intermittent~ under all operating conditions, and means are provided for inhibiting the operation of the circuit responsive to vibration of the sensing member at any instant during which sound is produced by the sound generator.

2. A bite indicator as claimed in claim 1, wherein the sensing member includes a piezoelectric crystal whereby an alternating signal is produced when the sensing member vibrates.

3. A bite indicator as claimed in claim 2, wherein the circuit responsive to vibration of the sensing member comprises a voltage controlled oscillator operative, when the level of the output signal from the piezoelectric crystal exceeds a predetermined threshold, to produce a pulsed signal having a frequency related to the amplitude of vibration of the sensing member.

4. A bite indicator as claimed in claim 3, wherein the voltage controlled oscillator is adjustable so that the frequency of the pulsed signal may be varied for a given speed of line movement.

5. A bite indicator as claimed in claim 3 or 4, wherein the means for inhibiting the operation of the circuit responsive to vibration of the sensing member at any instant during which sound is produced by the sound generator comprise a sampling circuit arranged between the piezoelectric crystal and the input of the voltage controlled oscillator which sampling circuit allows signals to pass to the voltage controlled oscillator only when the voltage controlled oscillator output signal disables the sound generator.

6. A bite indicator as claimed in claim 5, wherein a delay circuit is provided to prolong the time during which signals are inhibited by the sampling circuit from reaching the voltage controlled oscillator.

7. A bite indicator as claimed in any preceding claims, wherein the sound generator includes a two-tone tone generator and means for alternating between the two tones when the line movement speed exceeds a predetermined threshold.

8. A bite indicator as claimed in claim 20r any claim appended thereto, wherein in order to enable the sensitivity of the bite indicator to be adjusted, at least one variable gain amplifier is provided to amplify the output of the piezoelectric crystal.

9. A bite indicator constructed, arranged and adapted to operate substantially as herein described with reference to, and as illustrated in, the accompanying drawing.