Universal Analog Hardware Testbench

A $35 TEACHING AID FOR BASIC ELECTRONICS, AND AN INVALUABLE EXPERIMENTAL SETUP FOR THE ELECTRONICS HOBBYIST.

Teaching basic Analog and Digital Electronics at undergraduate level consists of theory classes with hands-on-training conducted in an electronics laboratory equipped with Oscilloscopes, Function Generators and Regulated Power Supplies. Students are taught the characteristics of basic components like diodes, BJTs, FETs, OPAMPs and Digital devices.

Carrying out practical laboratory experiments by students reinforces classroom teaching of theory. Standard laboratory equipment is often beyond the reach of several educational institutions worldwide because of the large cost element involved. Practical laboratory experimentation is therefore curtailed. 

To overcome this drawback I set about the task of building a low cost teaching aid for basic analog / digital electronics. This would enhance the availability  of laboratory test equipment to educational establishments and the student community.

My primary goals were the following:

• Should be a stand-alone system
• Keep the hardware cost to less than $40.
• Use readily available components
• Keep the fabrication simple so that students could fabricate it themselves.
• Cover all experiments related to basic components like diodes, BJTs, FETs, OPAMPs and Digital devices.

What has emerged is an Automatic Test Equipment (ATE) system with the following features:

• Hardware built around a dsPIC30f4011 micro-controller
• Serial interface to a host PC
• Six ±10V, 10Bit analog input channels with an input impedance of typically 1MΩ and a maximum  sampling rate is 2 mega-samples/sec.
• Three ±10V, 10Bit, analog output channels with a throughput rate is 20 kHz, two with a drive capability of ±10mA and the  third power amplified to provide a drive of ±200mA.
• Four buffered digital I/O channels
• For ease of availability and in order to provide power to the circuits under test, a standard PC SMPS used as the power supply.
• Micro-controller operations commanded by a Host PC using a GUI developed in Visual Basic. With the database manipulation and graphing properties of .Net 2 being fully exploited.
• The hardware cost was $35.

The  ATE system fulfills the requirements as an analog / digital laboratory teaching aid. Effectively a combination of a power supply, programmable signal generator and digital oscilloscope it would also meet the requirements of hobbyists and electronic enthusiasts.

By providing technical data and executable software free for non-commercial use I wish to encourage the computer aided teaching of basic electronics.

View a demonstration of one of the electronic experiments:

I look forward to any questions or feedback, contact me at:

Email: [e-mail]
Webpage: http://www.ajoyraman.in

Step 1: Hardware Block Diagram

The simplified block schematic of the ATE system is shown. For ease of availability and in order to provide power to the ATE unit and the circuits under test a standard PC SMPS is used as the power supply. Three fuses are added in the +5V, +12V and -12V lines from the SMPS to the ATE unit for safety as the SMPS though short circuit protected is rated for a much higher current capacity than that required for testing of simple circuits.
 
The ATE-Unit is connected to any available serial port on a PC with Windows XP / Windows 7 operating system. It is also possible to connect the unit to the PC USB port using a USB-Serial port adapter. This serial port connection along with the “Universal Analog Hardware Test Bench” Ver1.0 software provides communication with the ATE-Unit.
 
The circuit under test can be rigged up on a standard breadboard and powered from the power sockets provided. Power to the ATE and to the circuit under test comes ON only when the power switch on the ATE unit is activated.
 
The ATE unit provides three ±10V, 10Bit, analog output channels Vout1, Vout2 & Vout3 to the circuit under test. While Vout1 & Vout2 are Op-Amp outputs with a drive capability of ±10mA, Vout3 is power amplified to provide a drive of ±200mA.
 
Six ±10V, 10Bit analog input channels (Ain1 – Ain6) with an input impedance of typically 1MΩ are provided to read back analog data from the circuit under test.
 
Four buffered digital I/O channels (Dout1-Dout4 & Din1-Din4) are also provided for connection to the circuit under test.
 
A ‘Microchip’ DSPIC30F4011 micro-controller which interfaces with the Analog/Digital I/O and is connected to a PC through a serial interface forms the heart of the ATE system. The micro-controller operations are commanded through the serial link by the Host PC using the dedicated ATE software.

Comments

[kbaake]

First of all: Thanks for this great project,...

but I would recommend an "upgrade":

It gets harder these days to get a PC with serial interfaces,.... by using the FTDI FT232 u could build this to be USB-ready.

BTW: When it´s come to the question which microcontroller to use, I would prefer an arduino-style atmel (ATMega-series), which is much easier to programm and offers a great range of functions.

[ajoyraman]

Thanks for your valuable comments !

I chose the dSPic for the fast clock rate 96 Mhz which could go up to 120 Mhz this is very important for the waveform capture DSO mode and currently permits capture of signals up to 50 kHz.

I considered the arduino-uno as easily available with a good programming IDE, unfortunately it operates only at 16 Mhz. The recently released arduino-due running at 84 MHz could be a possibility now. I am considering this.

Regarding the 232 interface I am currently using a USB-serial converter and it works well. It possibly contains the FDTI chip.

The feedback from you is very sensible as the arduino-type is more readily available. Possibly addition of a suitable shield would suffice.

I will keep this in mind.

Best Regards

[subinznz]

where and when can i buy one im in NZ

[ajoyraman]

Thanks for your inquiry. I built it as a DIY system and have given all details to build one yourself. Would be wonderful if you do it !

[bricabracwizard]

Great 'bile! Can this be run on a Mac?

[ajoyraman]

Thanks for the 'short & sweet' great comment.
No ! Wrote it for Windows. Thinking of a QT version.

[Elsuerte]

http://rostest.info/

[amandaghassaei]

really well done project! have you had a chance to run a class with this yet?

[ajoyraman]

Thanks for your comment. Unfortunately I do not teach. However, I am trying to contact local colleges to get them interested in this system. I would appreciate any help in spreading the word around in your part of the world.

[rajsri30]

Great Job. Missing all the fun that we used to have in ADE. I will try to do my piece in spreading the word.

[msuzuki777]

Well done. It is nice to see a professionally written Electronics Instructable.

LOG

[ajoyraman]

Many Thanks to msuzuki77 and ASCAS for your encouragement , this makes my effort worthwhile.

[ASCAS]

This is great. This should get featured, you made a great effort on making an instructable like this. Posting complicated instructables is something I am lazy in doing.

Great job!

[ajoyraman]

A retired electronics professional this submission aims at giving something back to the electronics community, particularly students.

Kindly add your valuable vote to my Hack It! contest entry.

[christinaelsi16]

An innovative piece of work especially for student community. It can be taken up further.

[blkhawk]

Sir, you got my vote!

[womai]

This is an extremely well-made, professionally executed design. I really like the attention to detail - fuses for the power supply, trimmers to fine-adjust the input attenuators, and so on. The software is well thought out as well. I really hope this will see adoption in classrooms.

[ajoyraman]

Thank You very much.

I appreciate your valuable comments.

[bkp1971]

Really worth it. Looking at the number of lab equipments and the manual effort i put to do these experiments during my college days.