Any Experts here? Vibration Pulse Device for attracting predatory fish idea..

[quentinsaunders1]

Can any1 give me an idea of creating this device, or perhaps explain how you would go about it... See details below...


Overview:

-A smallish stand-alone circuit (preferably the size of a cigarette pack or hopefully much smaller) that either plays a low frequency sound, or, produces a low frequency vibration.
-It will be used underwater in a thin waterproof casing, plastic or metal depending on which works best or cheapest. I assume that sound should get through easily if speakers/vibrator directly face the casing. It will be used to attract predatory fish.
-I assume it should run on a small 9V battery.
- Apparently most tiny speakers go only as low as 200hz, this is the maximum hz I would want in that case.

- The cost of the components themselves (not referring to the labour/design costs of course) should be cheap


The Sound/Vibration needed is quite specific: (It is the sound made by struggling/wounded fish underwater)

-Intermittent, low frequency, pulses. Around 25-200Hz. (Not khz or mhz)
-It will have to be irregular pulses,not a continuous tone, lets say 2-15 rapid pulses per second.
-Does not have to be very loud, as sound travels really well underwater. But quality should be reasonable to produce the correct tone/frequency.
-"Sound Track" or "Vibration Timer" of lets say 10 seconds can simply loop until battery is removed or runs flat.
-Im assuming sound playback is the best solution (opposed to a vibrating motor), as the specific sound needed can then be created digitally for simple playback.

Then again, a vibrating motor would be a far smaller and simpler circuit. if it can be made to send out a low frequency intermitted pulsed vibrations (like a low tone cellphone vibrator which randomly pulses…

 

[Externet]

As the sound must be "quite specific" to fit your needs; I suggest you record such sound and replay with a MP3 player inside a 'baby food' jar, with earphones or piezoelectric speaker, all in the jar. It will propagate to the wet outside.

 

[dr pepper]

Very low freq's are tricky to reproduce with a small device as the wavelength is long compared to the device.
A cheap 3" speaker might so the trick if driven reasonably hard, and might be improved by adding some weight to the cone, a solenoid might be a better idea, but that'd probably onyl go to 50hz or so.
The idea kinda calls out for a microcontroller, if you have any programming experience that is, I have a thrown together pic micro powered signal generator that uses a r-2r ladder and goes to around 60kc with low distortion.

Oh yes welcome here.

 

[cowboybob]

Welcome to ETO, quentinsaunders1!

I like your idea. Didn't know if you had heard of these guys: **broken link removed**

They have some incredible lures that incorporate your idea, and they are cheap **broken link removed**.

 

[chemelec]

Just use a 555 to Produce a Slow 1 or 2 Hz Pulse, through a 100 uF cap and into a Speaker. (Thump, Thump, Thump ........)
It will help to attract fish.

 

[quentinsaunders1]

Thanks for the information thus far guys! Appreciate it...

Would someone mind to draw me a small basic diagram of a circuit idea plz? Or perhaps just explain what the circuit would need...

Perhaps a cost estimate?

Would really appreciate it.

Thanks thanks

 

[dr pepper]

A 555, 3 resistors, 3 capacitors, piece of veroboard, speaker, case, bits of wire, battery & connector.
Probably under 10 quid.

 

[chemelec]

MANY, MANY YEARS AGO, this was published in a Electronic Magazine. (I Think in 1960's or early 70's)

These parts are probably hard to find now, Especially a Crystal Earphone.
But it can be done quite Simple with a 9 volt battery, a 555, a few resistors and capacitors and a small speaker.
Cost depends on what parts you may already have.

I can post you a circuit a bit later today.

 

[dr pepper]

The trans is sometimes refered to as a lt77, ebay probably has some.

 

[chemelec]

This is as Simple as you can get.
Just Use a Small Speaker 2 or 3 Inch Diameter.
Impedance Not Important, This was Tested with an Old 8 Ohm Speaker.

It Goes: Tick, Tick, Tick, Tick .................
For a Slower Ticking, use a Higher Value Capacitor in place of the 33uF.
Examples 47uF or 100uF

For Faster Ticking, use a 22uF or 10uF.

Or Change the Resistor Value

The Faster the Ticking, the More Current it will draw from the Battery.

 

[chemelec]

The trans is sometimes refered to as a lt77, ebay probably has some.

I have Many of these transformers also.
("Mouser", Part Number "42TL009")
I Even have those OLD Crystal Earphones.

 

[Tony Stewart]

Considering the vibration would stem from the tail frequency, I think 10Hz with harmonics of that from a coin size offset mass vibrating motor with a CR123A Lithium battery.
**broken link removed**
$10 plus battery $2 3V
for fancy, one can make it burst in noise with some counter timer to switch the power and be encapsulated with a waterproof switch. or waterproof micro-connectors.

 

[Tony Stewart]

Is there any research to indicate efficacy?

 

[dr pepper]

you can still get lt77's in the uk, but they are drying up, I have non left, lt44's which were used for transistor drivers were also common, they are dissapearing too, but then they havent been in commercial stuff for, dunno decades?

 

[Tony Stewart]

HEP230 replacement
NTE104 TRANSISTOR PNP GERMANIUM 50V 10A TO-3 AUDIO POWER AMP

 

[chemelec]

HEP230 replacement
NTE104 TRANSISTOR PNP GERMANIUM 50V 10A TO-3 AUDIO POWER AMP

This is a Very Old Design, when Germanium Transistors were the Most Common.
A 10 Amp Transistor is a HUGE OVER KILL in this circuit.

Considering this circuit uses Two, AAA Batteries it is only running at 3 Volts.
And with the Transformer, Connected as in the Circuit, it has a Resistance of 250 Ohms.
So Maximum Current is just 24 mA.

Probably just a 2N3906 Transistor would work.
I Can TEST it out, If anyone really wants to build this circuit.

 

[Tony Stewart]

This is a Very Old Design, when Germanium Transistors were the Most Common.
A 10 Amp Transistor is a HUGE OVER KILL in this circuit.

Considering this circuit uses Two, AAA Batteries it is only running at 3 Volts.
And with the Transformer, Connected as in the Circuit, it has a Resistance of 250 Ohms.
So Maximum Current is just 24 mA.

Probably just a 2N3906 Transistor would work.
I Can TEST it out, If anyone really wants to build this circuit.

I disagree with your analysis. This is a 3V cct with a very low duty cycle and low frequency pulse generator that can draws many Amps limited only by the Rce of the Germanium and Rs of the primary coil. The reason a 10A transistor was chosen half a century ago was it was the best choice for low Rce and a 3V relaxation oscillator.

Now you can do the same with a power low threshold MOSFET. The theory of operation is to generate as much voltage as possible for the piezo output exciter from V=LΔI/Δt using 3V THe large Cap does this with a DC current limit of 27k. Thus the average current is low due to the quick turnoff time and slow charge time.

It doesn't have to be PNP as NPN with reversed battery can do the same, but the Germanium just happened to be the best at the time.

So it will go tick, tick tick.... at an adjustable rate.

I was only showing that a current replacement part number was active, not endorsing the design.

Cheers,

Tony Stewart

 

[chemelec]

WORKS PERFECTLY with a 2N3906.
Current Draw Varies Between about 10 and 20 mA, Depending on output Frequency.
Trim-pot could be Increased to 10K for a Lower Frequency.

Want a Video with Sound?
I Can post that Also if it allows videos here.

 

[Tony Stewart]

With a better (split coil or) transformer, you can drive the transformer with larger current 50V spikes narrow enough into the ultrasonic range on the piezo to get bigger fish.

To compare, one would have to measure the Joules per pulse.

 

[chemelec]

With a better (split coil or) transformer, you can drive the transformer with larger current 50V spikes narrow enough into the ultrasonic range on the piezo to get bigger fish.

To compare, one would have to measure the Joules per pulse.

MORE IMPORTANT is the EFFICIENCY of your TRANSDUCER!

The Circuit I Just Posted it QUITE LOUD with the Piezo I use.

Not Sure that would attract Bigger Fish.
Many Boats have Ultrasonic Transducers to Help prevent Barnacles.
They Don't attract Fish.

With Ultra Sonic, your only option would be a 24Khz or 40Khz Transducer.
And you would need to tune to that Frequency.
Or a Very Expensive Sonar Transducer.

As Very Few Piezo Speakers work in the Ultrasonic Range.