I'm a beginner, having completed one project up to now. A light detector for blind people, which turns light into sound (the brighter it gets, the higher the tone).
Now, I want to make a version accessible to deaf-blind people, by using vibration rather than sound.
I've got it working by having the vibrator on a PWM pin and mapping the AnalogRead input (0 to 1023) to the AnalogWrite output (0 to 255).
Of course with the vibrator, there is not much room for variation between a week and a strong vibration, whereas in the sound version I set a range of 1000 Hertz and so even slight changes in brightness can be heard.
If I could use 2 or even three vibrators, I would have mor room for variation, I think.
Unfortunately, my understanding of things electronic is rudimentary at best.
If I put, say three vibrators on three PWM pins and switch them on individually according to brightness, would that work?
Would a transistor help and where would I place it in the circuit?
I'd be grateful of any advice. (I'm blind myself, so can't use diagrams.)
Hi,
I would like to start with the vibrating motors.
Those are often very small rotating motors of 3V with a weight that is not in the center. It is not easy to set a certain frequency or strength.
Do you know exciters. They are speaker drivers without a cone. If you put one of them under each fingertip, then you can sense a lot of information.
There is a library for the Arduino Uno that can set the frequency and the volume for a signal, it is called "ToneAC" (GitHub - teckel12/arduino-toneac: Enhanced version of the standard tone library).
The volume is created with the PWM signal, only a few different volume settings are possible and it is only for one output signal.
You need something to amplify the signal. For a vibrating motor, a transistor will work. There are also chips with 8 darlington transistors to drive small motors.
Perhaps it is possible to use the Arduino Uno without amplifier, since it can output up to 40 milli-ampere with pin.
Question for others: Is there something similar to exciters that are small enough to put under a fingertip. Perhaps a piezo element? What is the smallest exciter?
Thanks a lot for the info on Exciters. I'll chekck that out.
For the time beeing, I'll try to improve the behavior of the vibrator, since I've already got it. I also have PNP transistors. Can you tell me how to wire the circuit?
Thanks!
The Arduino Uno is a 5 Volt board and a darlington transistor has a voltage drop of 1.0 to 1.5 Volt. That matches well with a vibrating motor of 3 Volt.
A NPN transistor will also work.
Do you really want to use the PNP transistors ? Then you connect the emitter to 5V, the base via a resistor to a output pin of the Arduino board and the collector to the vibrating motor and the other side of the motor to ground.
Because the motor is an inductance, you also need a fly-back diode and a capacitor over the motor. A fly-back diode is a 1N4007 in reverse, parallel with the motor.
How about ten vibrators, one for each digit of the hand , with both hands palms down , the little finger of left hand becomes digit-1 , left thumb becomes digit-5, right thumb digit-6 and right little finger digit-10. Letters are spelled as decimal numbers so A =1, B=2, etc. , so K= 11, ( two pulses of left little finger. Numbers are identified by pulsing the vibrators slightly longer, such that letters are 'dots' and numbers are 'dashes'.
Option-B
Use only fingers , for binary, . Left four are High 'Nibble' and right fingers are Low 'Nibble' . This requires some way to convert hexidecimal, so maybe not practical.
Another approach. I've now got two vibration motors working parallel on a PWM pin and GND. The result is just what I want.
But will this eventually burn up my Nano or can it handle it? The vibration motors each have a nominal voltage of 3.7.