MEMSIC Accelerometer for Robots & Design of Bipolar Junction Transistor as a Switch

One example of accelerometer applications to be discussed is the Balancing Robot that uses specially MEMSIC2125 accelerometer applications. MEMSIC2125 is a dual axis accelerometer sensor measurement of thermal motion. Accelerometer is capable of measuring dynamic acceleration (vibration) and static acceleration (gravity) with a range of ± 2g.

Some features that can be done by this accelerometer is as

follows:

1. Measure 0 to ± 2g in every axisnya; has a resolution of less than 1g.

2. It has a compensation temperature range 0 º - 70 º C.

3. It has a digital output / pulse on dual axisnya.

4. Analog output to measure the temperature (Tout pin).

5. Low current operations; less than 4mA at 5V voltage.

Internally MEMSIC small 2125 has heating function or is useful as a heat bubble that floated in the sensor devices on the robot. When there is an affecting gravity, the bubble is moving. Movement "bubble" is in sensing the sensitive thermopiles (temperature sensor) and turn it into an electrical signal relative to the force of gravity. By comparing the temperature sensor, both static acceleration (gravity and tilt) and dynamic acceleration in the rate of a wheeled robot can be detected. Pulsars are produced in sets have 50% duty cycle at 0g. Balancing robot using LEGO media also can be applied. in the media robot

Design of Bipolar Junction Transistor as a Switch

There are three conditions in the application of Bipolar Junction Transistors. This condition is an active condition, cut off and saturation. Active conditions used in the manufacture of amplifiers. While the cut-off and saturation used in the design of BJT as a Switch.

when menhidupkan a relay or drive DC motors with microcontroller command, needed a driver interface, the microcontroller does not have a current sink or source for mendrive relay or DC motors or other loads. Follow these simple steps in order to design a driver.

1. Determine which expenses will be in the drive

2. Note the working voltage and load current required.

Suppose Relay 12V/100mA.

3. Choose the type of BJT is able to mendrive voltage and current.

Comunitas X-Sys ROBOT

Suppose that the HFE FCS9013 NPN 100 and Ic 400mA max

4. Put the relay in the collector and emitter to ground. Connect the 12V on

the relay that one again.

5. Living the base that has not been connected. Base need for resistors

not too high currents into the base of BJT.

6. When HFE 100 with current Ic = 100mA, then known Ib = 1mA. Careful note

current source microcontroller, is sufficient for driving a BJT base.

7. When the microcontroller voltage of 5V and 0.7V voltage VBE of the BJT

Vr = 4.3V.

8. Flow Ib = 1mA then Rb = 4.3Kohm.

9. Please try and measure whether it has reached saturation VCE.