Audio Frequency coversion for hard of hearing.

[ajury]

Hello, I am trying to help a 9 year old with hearing problems get involved in transmitter hunting.

The reciever he is using puts out a rising tone when the signal is stronger. Problem is he can not hear the higher tones.

I am considering building something to covert the audio to a display or changing the speed of a pager motor (it would be nice to not have to look at a display while looking for the transmitter).

Suggestions? My best guess is to use a frequency to voltage conveter to do the display but not sure how to do the motor.

Thanks, Art.

[Sambuchi]

hello ajury and welcome to the forum..

I like the idea of using a pager motor for the higher tones...

Maybe just the higher tones... so you dont have to feel the motor shaking all the time..

I also like the idea having the motor off the circuit board..vibration can damage the ciruit board.

My best guess is to use a frequency to voltage conveter to do the display but not sure how to do the motor.

ok this is very simple and people here can help you with this. What do you know about electronics... experience?

I will take a guess that your reciever has a nice clean analog signal going to a chip.. that chip will output another signal to a speaker to make a tone.

hard way..
jumping the analog signal going into the chip.. to a small micro controller that has an ADC is a solution. as the analog signal reaches a level you want to turn something on, you can.... and as it get higher you can apply more power to the motor... using PWM (pulse width modulation)

easy way
here is a circuit that will run a fan from a analog signal.. and the signal gets higher the fan will turn faster.. by playing with this circuit .. this could be the desired path.

http://www.analog.com/library/analogdia ... eed_04.gif

i hope this quick and easy post helped some..

[ajury]

Just what I wanted, I should have thought of a fan controller.

I think I will try it with the motor on all the time for consistancy, we'll see how it works out.

I know a fair amount about electronics I build most of my stuff dead bug style but am starting to look at manhattan style. I think I have a few 741's around, just need to find a pager motor and power transistor, maybe Ill use a fan for cooling until the heat breaks.

The reciever I use for beginners puts out a audio tone, basically an audio field strength meter.

http://www.users.bigpond.net.au/vk3yng/ ... manual.htm (if you are interested.)

To set up Sam with his own gear I will probably find the RSS signal in one of the old ham trancievers I have and use that to make an audio signal with a voltage to frequency converter. Its nice to have the audio as I usually have kids hunt in pairs, otherwise the equipment gets to heavy for them, My son has been hunting with him and they are having a good time.

You will be able to see photos of them at verdant.org in a few days.

Thanks a bunch, just what I was looking for!

Unless someone comes up with something that requires only 1 part and directly interfaces with the brain......

Thanks art

[Bob Scott]

Hi Mr. Jury,

I think audio may still be your best bet if you don't want to use the sense of sight, and you can modify the audio to stay in a one octave range if the child still has a one octave hearing range.

Send the varying frequency signal of your ranging box to the input of a digital 4 bit counter CMOS IC. Wire your original signal and each of the 4 outputs of the counter IC to a single pole 5 position switch. Connect the output of the switch back to the amplifier/speaker system of your original ranging box. This way the switch can select the original signal, or any of 4 outputs from the IC.

This way when the frequency of the original signal goes too high, the kid can rotate the switch to any of the other outputs from the counter IC. Each successive output of the counter IC carries a tone exactly one octave lower that the previous switch setting.

What do you think?

Regards,
Bob

[Robert Reed]

Ajury
Just a thoght - I am not sure of the audio range required here or the specific limits in frequency of the childs hearing, so I am at some dissadvantage in my reply. It would be possible to feed the audio tone into a schmidt trigger for proper digital shaping and then drive a toggle flip-flop to bring the whole audio package down one octave. This can be repeated as often as you desire, even to the point of geiger counter style. Since the out put are square waves, they would give good crisp speaker response even at very low rep rates. Most common logic DIPs come with dual bistables per package (sometimes 4) so one 14 DIP could do the trick. Use a "D" type bi-stable with the `Q NOT` wired back to the data in pin for toggle operation. Very simple if this would fill the bill for you.

[Sambuchi]

Art glad to help..

Yes all you would need is a 741..couple resistors for the circuit.

Bob and Robert had good ideas too. Their ideas would keep the reciever functionality the same... which is always a great solution.

Look forward to see your photos.

Good luck

[ajury]

I also am not sure of the range of his hearing, but know he was not hearing all of the tones from how he was hunting.

Its even more interesting because he reads lips and my style of teaching is to put something in a kids hands and show him. Well he is looking at what I am showing so now he cant hear what I am saying! What a bummer for him, he is a good kid though so I will get something going before the next hunt.

Ill also keep reading here for suggestions. I fiddle with electronics but in order to find something really simple I knew it would be best to talk to the pros,

Thanks again.

Art.

[Chris Smith]

A simple frequency to voltage chip can change the frequency into a voltage signal for processing.

Which way you go from thee is up to you.

I would use a 10 segment led like the LM 39....14,15,16 or 17 series to take the voltage and make it into a visual signal?

Pager motors on the other hand can usually be found at “All electronicsâ€

[Gorgon]

Hi Ajury,
If the boy can hear at least one frequency range, my idea would be to make this sound just one frequency, but interrupted with a faster rate for the rising frequency (of today), and a slower rate with the falling frequency (of today). just a slower or faster beeping of one frequency. I would assume that a 50/50% pulse/pause ratio would be the best, and that you just vary the period frequency.

Another and maybe better solution is to fix the period and vary the ratio (like PWM). This way you'll get a short beep in the start, increasing to a continous tone 'at target'.

I've seen similar equipment used for target practice on a shooting range for blind people. It is amazing that they hit a normal target with this, but they do!

TOK

[ajury]

Wow so many great ideas!

The led's will work, but I would need to use more than 10, that is one of the good things about the audio field strength meter it is much easier to notice small changes in signal strength. More advanced hunters can do ok with only 10 segments but novices tend to move to fast and miss peaks and nulls. I have built a few with 40 segments and that works fine (for a mobile unit) lot of soldering though.

The small changes are important both for Transmitter hunting and showing how antennas work. Its really amazing how fast someone learns about antenna patterns with an audio field strength meter and an antenna in hand.

I think the 1 octive solutions are the best for me, although I am going to get a pager motor and fiddle with that just because it sounds fun. I also hope to mess with a pwm circuit.

Ill try to report back in a month or so.

Thanks,
Art.