Analog Experiments Anywhere
Two DIY micro-controller based USB connected electronic units which along with the Texas Instruments Analog System Lab Starter kit and a laptop permit you to conduct analog experiments anywhere.

It would be wonderful if senior students and laboratory supervisors built these units so that they could be used in their laboratories by freshers.




Aj-SigGen-PS http://ajoyraman.in/DDS_SigGen_PS.html

Aj-Simple-Scope http://ajoyraman.in/USB_Simple_Oscilloscope.html

Analog System Lab Starter Kit ASLKv2010 http://www.uniti.in/teaching-material/analog-system-lab-starter-kit

Step 1: Aj-SigGen-PS

Analog Experiments Anywhere
This unit is designed to compliment the Aj-Simple-Scope and serve as a teaching aid for budding engineers, electronic enthusiasts and hobbyists.

This USB connected unit implements a microcontroller based DDS Signal Generator providing Sin and Triangular waveforms with adjustable magnitude and offset up to 50 kHz. TTL and 1 V square waves are simultaneously provided. Additionally 12V and a variable +2 to 7V output with a total capacity of 1W is provided to power external circuits under test.


Step 2: Block Schematic and Function Description of Signal Generator and Power Supply Unit

Analog Experiments Anywhere
For ease of portability the unit is powered and controlled from the USB port of a PC.


Two PIC18F14K50 microcontrollers are used to provide the functionality of the unit.

The first PIC microcontroller implements the following functions:

• Communicates with the host PC for enumeration as a USB to UART device

• Sets up the unit as a 500mA device

• Switches on power to the DC-DC converter

• Provides the complimentary square wave drive to the DC-DC converter

• Acts as a USB communication interface to the second PIC

• Provides the Amplitude reference for DAC2

• Provides the digital word for DAC1 giving the offset value.


The second PIC microcontroller implements the remaining DDS functions

• Direct Digital Synthesis (DDS) signal generation

• Sin/ triangle word output to DAC2

• TTL and 1 V square reference output


The DC-DC converter is a driven 1W, 5V to 12V operating at 100 kHz. The +12 V output is fed to a linear regulator to provide a variable +2 to 7 V output controlled by a variable potentiometer.

The DC-DC converter provides full protection to the host PC USB port as its outputs are short circuit and current limit protected.

The circuit under test can be rigged up on a standard breadboard and powered from the power sockets provided.
Analog Experiments Anywhere
Aj-SigGen-PS_Tech-Manual-Final.pdf1 MB

Step 3: Aj-Simple-Scope

Analog Experiments Anywhere
This unit is designed to compliment the Aj-SigGen-PS and serve as a teaching aid for budding engineers, electronic enthusiasts and hobbyists.

This USB connected unit implements a microcontroller based 2-Channel Oscilloscope providing continuous sampling rates up to 100 ksps and 20 Msps using equivalent time sampling. Common DSO features such as spectrum analysis, waveform capture and data saving are provided. The input range is 12V with additional gain settings of X2 and X5. Trigger and sweep options are also provided.

Step 4: Block Schematic and Function Description of the Simple-Scope Unit

Analog Experiments Anywhere
For ease of portability the unit is powered and controlled from the USB port of a PC.


A PIC18F14K50 and dsPIC30F4011 microcontrollers are used to provide the functionality of the unit.

The first PIC microcontroller implements the following functions:

• Communicates with the host PC for enumeration as a USB to UART device

• Sets up the unit as a 200mA device

• Switches on power to the DC-DC converter

• Acts as a USB communication interface to the second PIC


The second PIC microcontroller implements the main Oscilloscope Functions

• Analog to Digital conversion of the CH1 and CH2 signal conditioned inputs at the required sampling rates

• Trigger interrupt handling

• Responding to serial commands from PIC1 and sending back the acquired data.

• A Busy signal is also generated


The dual-charge pump circuitry of the MAX232 is used as a DC-DC converter to provide a nominal 10V to all the analog circuitry.
Analog Experiments Anywhere
Aj-Smple-Scope_Tech-Manual-Final.pdf1 MB

Step 5: Typical Test Results Using the ASLK

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Refer to the Analog Systems Lab Manual from Texas Instruments

http://www.uniti.in/images/teaching-material/aslk-lab-manual-2edition.pdf

It is extremely easy to setup the analog experiments in the lab manual on the kit and test them using the Aj-SigGen-PS and Aj-Simple-Scope units.

The kit is powered from the Aj-SigGen-PS which also provides test signal inputs as required. The wave-forms at selected test points on the circuits are captured using the Aj-Simple-Scope and saved as image files on the laptop.

Typical wave-forms which have been captured are shown.

These demonstrate the capabilities of the ASLK and how to test the circuits using the two DIY units presented here.

For further details of the Hardware and freely downloadable Software kindly visit http://www.ajoyraman.in


 
 

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