Introduction: Transistor Vibrator Kit
This article shows you how to make a transistor vibrator kit.
The circuit turns on the vibrator actuator when the ultrasonic signal enters the sensor.
The first circuit is the ultrasonic receiver. The second circuit is the vibrator driver.
I used the ultrasonic receiver circuit from this article:
Components: ultrasonic sensor - 3, high-frequency transistors - 5, general-purpose transistors - 5, power transistor/darlington pair - 2, heat sink - 1, matrix board - 1, insulated wires, metal wire - 1 mm or 0.9 mm, 100 ohm resistors (high power) - 10, 1 kohm resistors - 10, 470 nF capacitors - 10, 100 kohm resistors - 5, 470 uF capacitors - 5, ultrasonic transmitter (you can use certain ultrasonic senr).
Tools: USB Oscilloscope, pliers, wire stripper, ultrasonic signal generator.
Optional components: solder, encasement/box, LED/bright LED - 3.
Optional tools: soldering iron.
Step 1: Design the Circuit
The minimum transistor collector voltage across for Darlington pair power transistor will be 0.9 V. Thus the maximum voltage across the LED will be 2.1 V.
If you replace the Darlington pair transistor with a power transistor (to reduce the cost of components) then you will need to connect a 100-ohm resistor in series with the LED because the minimum transistor collector voltage might fall below 0.2 V.
More information about the ultrasonic receiver can be found here:
Step 2: Simulations
The ultrasonic receiver circuit seems to have a 100 ms delay. The trigger turns ON from 0 seconds, representing the presence of an ultrasonic signal (red rectangle in the first graph). However, the circuit is producing an AC output 100 ms later.
The frequency simulations show a small bandwidth because the old PSpice simulation software student edition does not have radio frequency transistors. However, the ultrasonic receiver might still work with general-purpose transistors.
The minimum Darlington pair collector voltage fell to about 0.6 V. That means the transistor model is inaccurate.
The maximum current across the vibrator is about 24 mA. However, my model of the vibrator (100-ohm resistor) could be inaccurate.
Step 3: Make the Circuit
The making of the circuit was delayed for many weeks due to certain components not being available for the vibrator driver.
The base resistor (Rb1 and Rb2) will need to adjusted to the specific transistor current gain. The 150 kohm value Rb1 and Rb2 resistors might not be suitable.
Step 4: Testing
I connected the ultrasonic transmitter component directly to my signal generator. You can make your own signal generator with a 555 timer and at least a 9 V power supply.
I also made a small hole in the receiver plastic bag to improve the propagation of ultrasonic waves.
The bright LED turns ON when the ultrasonic signal is applied to the sensor. You have to increase the volume to hear the vibrator.
Participated in the
Make it Move Contest 2020