Golden Rules For Electronic Circuit Design

- All components must conform to the specified temperature range. For resistors, de-rating of power rating at peak temperature must be considered. For capacitors de-rating of capacitance, leakage and increase in ESR at peak temperature may be important. For other components such as diodes and transistors, parameters such as recovery times and current gain vary with temperature and must be considered at extreme temperatures. In summary, no design calculation must be left to chance (as is often the case with designs put together in haste), temperature effect calculations are indispensable to success.

- Devices connected to interfaces must be well protected from ESD (Electrostatic Discharge) damage. ESD damage may occur at the time of prototype construction, during manufacturing or during use. Contrary to common misconception ESD at the time of production may not render a device defunct, but may cause progressive deterioration which may result in field failure. Therefore built in ESD protectors are necessary and Mansi Engineering ensures that all its designs incorporate them where necessary. IEC 61000-4-2 is a widely accepted ESD test conformance standard. ESD protectors include MOVs, TVS diodes, ESD Protection Clamping diodes and the newly introduced Polymer based devices. Selection of the right type of protector depends on capacitance that can be tolerated without signal deterioration and other factors such as tolerable leakage current, cost, pin outs and board area required. In addition, ESD protectors must be placed as close as possible to the signal entry location and as far away as possible from the device being protected so that the resulting large trace impedance attenuates the high frequency ESD energy as it travels towards the protected device. Zener or TVS diodes must be placed between power supply lines and ground to absorb ESD energy traveling via other protector diodes towards power supply line, while the device is powered off.

- Terminals connecting to inductive sources must be protected from switching overshoots or undershoots using clamping diodes or other devices. Long traces that carry heavy currents may act as sufficiently large inductors to cause unwanted switching transients and therefore protection is necessary.

- Signal lines must be well protected from radiated and conducted EMI. Ferrite beads and capacitor filters are effective means to block EMI.

- Within limits of budget, every design must incorporate sufficient protections from wrong connections, such as battery polarity reversal and accidental grounding of an output line. Large resistors are recommended to be used in series with microprocessor outputs driving drivers that drive large inductive loads. This ensures that the processor is well protected from switching transients.

- Functioning of the system at power up must be analyzed. For example it is important to deploy pull-up resistors on microprocessor output signals that need to be high on power up. Similarly functioning of relevant parts when powering down deliberately or accidentally, must be analyzed. For example, when processor state saving is involved during power down, a power down detect functionality might prove indispensable.

- For EMC, it is recommended to use inductors (preferably shielded) to slow down sharp current rise and fall times. Sharp current transients cause a sharp varying and traveling electromagnetic field.

- It is important to assign test points to relevant nets. Especially all ground and power nets, bias or threshold points and other serviceable signals must have a test point, which add convenience during testing and troubleshooting. Test points may be free vias with suitable drill size to accept and retain stainless steel needles or header leads.

- Having an on board power on LED indicator has its own importance. It warns the engineer and people around that the circuit is live and prevents accidents."

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Article by
Department of ECE
Methodist College of Engineering & Technology , Abids

Methodist College of Engineering & Technology

Micro ATM: A Doorstep Banking System

Today, banks have realised that their next huge customer base is not in the urban setting but in the often-neglected rural areas. However, reaching this customer base is not so easy, primarily because the rural areas are not as infrastructure-rich as their urban counterparts. Simple tasks like going to the ATM and withdrawing money make people miss their working hours and, as a result, lose a significant part of their income as well.

To counter this problem, YES Bank has come up with an innovative technology called YES Sahaj micro ATM, worked upon by the team of Ajay C. Desai, Vaibhav Peshney, Sushanta Tripathy, Rupesh Kumar and Amulya Bisht—all working with the Development Banking section of YES Bank.

What is the need for a micro-ATM?

YES Sahaj micro ATM is a doorstep mobile banking solution-cum-mobile ATM device for the under-banked and unbanked population base. As other similar point-of-sale (POS)-based services are also available, what sets the YES Sahaj solution apart? Sushanta, vice-president, YES Bank, explains, “YES Sahaj is a mobile banking facility for the needy customers. As you have mentioned, there are other formats like biometric POS devices which provide similar services and are easily available in the market. What differentiates YES Sahaj in the sector is that its total life-cycle cost is signifcantly lower than the other products in the market which are very costly due to their high capex and opex costs.”

When asked about what prompted them to think about such a solution, Ajay Desai, president, YES Bank, shares, “YES Sahaj micro ATM was developed as a response to some ‘felt need’ of internal and external stake-holders. The next billion customer base, which is the target segment, can’t leave their business premises for banking transactions. YES Sahaj provides them with the convenience of the ‘doorstep banking’ services both within and beyond the normal banking hours. For customers, it provides the bare necessity of the doorstep banking, saving their wage loss to the tune of Rs 150 to 200 per bank branch visit. Cumulatively, this results in savings of around Rs 30 million to the customers.”

The Technology

The technology behind YES Sahaj is a combination of two very simple devices, viz, a low-power bluetooth printer and a low-cost mobile communication device, that have been interfaced to develop a full-blown ATM. The system consists of a specially programmed mobile handset connected to the central server using GPRS connectivity, and a hand-held thermal printer that automatically prints receipts as and when triggered by the server.

Since the device is targeted at rural areas where lack of adequate infrastructure is a prime issue, the ability to work with low power is of prime importance. A thermal printer is used here because it is much more suitable for portable applications than ink-based printers. 

Thermal printers work by heating a thermochromic paper that makes the heated areas on the paper turn black. Thermochromic paper, as the name suggests, is sensitive to temperature changes and shows the effect by visual blackening of the affected areas. Use of no ink eliminates the risk of spillage and also makes the equipment lighter. Most importantly, thermal printers use far less power than other conventional printers. Bluetooth technology implemented in the printer functions in power saving mode while providing a secure means of communication with the mobile handset.

Working of the system can be described as follows: First, YES Bank Ltd (YBL) shares the customer’s details including his account balance for the day. Following this, the business correspondent agent (BC agent) enters his login request through the mobile device. On successful BC login, the customer is asked to provide his debit card to swipe through the card slot in the Bluetooth printer. A debit card validation request is sent to the UPASS server. Upon successful validation, one-time password (OTP) and withdrawal details are sent to the customer’s registered mobile number. Else, an error message is displayed on the mobile screen.

OTPs are used because these are invulnerable to the drawbacks of static passwords where a hacker can make use of the password to access the account. This is of high significance in a rural setting where the users might not be tech savvy to understand the importance of keeping a password secure.

The OTP generated is shared with the BC agent and entered through the mobile device. Next, the OTP validation request is sent to UPASS backend server. After successful validation, the amount to be withdrawn is entered through the mobile device, and the mapping and validation are done at the UPASS backend server. 

Finally, a transaction receipt command is sent to the mobile device. The receipt is printed through the thermal printer, and the cash as well as transaction receipt are handed over to the customer. The transaction is concluded with a confirmation SMS sent to the customer, and End of Day data is shared by the BC with YES Bank for the customer’s account updation.

Some obstacles

The team faced its share of difficuties while creating such an innovative solution.

Vaibhav Peshney, regional finacial inclusion leader, YES Bank, shares some of the challenges, “The major challenge was to develop the system from a normal collection device to a mobile banking product. Customisation of the back-end servers and the front-end interface was a major task. Even for some of us who had been working in this sector for a considerable number of years, understanding the exact need of the target customer was again a challenge. In fact, these challenges only pushed us to think frugal and come up with our very own Frugal Innovation for Financial Inclusion (FI4FI) programme; YES Sahaj is one such innovation under this initiative.”

Rupesh Kumar, financial inclusion leader, adds, “For the initial workable collection module, it took only four months time for a basic product as cable collection device to be in place. The credit goes to both the teams for their dedicated efforts. We had to customise the product for banking requirements and standards and then train their back-end team to deal with the banking standards. After that, it has been continuous research and development which has helped in adding new features from time to time.”

Future expansion plans

Financial inclusion is an evolving sector. Customizing the product to the needs of the customers is a learning experience for all the players in this field. Amulya Bisht, associate, cites the example of YES Sahaj micro ATM, “YES Bank itself has gone through many phases of development to come out from a mere field collection device to a withdrawal and deposit platform and now to a complete doorstep micro-ATM-cum-teller. In coming days, many new features, including a more secure transaction mode, along with product customization to address other standard banking products like over- draft facility, will be added to it.”

The standalone services for micro ATM will be charged on a per-transaction basis. This amount will be very small as compared to the wage loss incurred by customers in visiting the banking premises.

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Article by

Department of ECE , 

Methodist College of Engineering & Technology , Abids

Methodist College of Engineering & Technology

Methodist College of Engineering & Technology , Abids

A Bird's eye view of Methodist College of Engineering & Technology (MCET)

MCET is a Non-Minority Educational institution,established in the year 2008,over 6.53 acre sprawling campus,situated at Abids, in the heart of the city of pearls, Hyderabad . The college is well connected by public transport from every corner of the city.

MCET is affiliated to Osmania University at the state level and with AICTE in the Central level.

Methodist College of Engineering and Technology strives towards excellence by imparting essential technical skills as well as a holistic approach towards grooming the students into responsible, worthy citizens of the future. Life in Methodist is not just limited to the classroom-teaching, but spins beyond the textbooks to develop character and thus mould total the personality of the students to carve a niche for themselves in the society.

Our Mission

To be one among the most distinguished colleges of Engineering with outstanding undergraduate teaching programs and excellent research facility.

To promote the spirit of holistic knowledge,leadership qualities,responsibility, and integrity in order to cultivate student excellence every single day.

The ultimate goal of the Methodist College of Engineering and Technology is to educate and graduate individuals who possess the technical and social competence and confidence to succeed in professional practice and advanced education, to be lifelong learners, and to exercise responsible citizenship. To accomplish this mission we have established the following objectives:

Sufficient knowledge and understanding of the appropriate scientific and mathematical fundamentals upon which the students can develop their professional skills.

Skill in integrating and applying professional knowledge to define problems and produce efficient, economic, and effective solutions.

Effective written, oral and graphic communication skills.

Awareness and understanding of diverse cultures and social conditions, past and present, in which their professional and personal endeavors will take place in order to strengthen the values needed to enhance the quality of life and contribute to the general welfare of society;

A commitment to continuing professional growth and the ethical development of their chosen discipline.

Our faculty has achieved a high level of technical competence in their field, but is committed to teaching and mentoring students. The campus has an atmosphere of open inquiry and exploration. This enhances the sound technical foundation that our engineering and technology students receive.

The engineering education program is demanding, but it develops broad skills in technical areas, an appreciation for the arts and humanities, writing and speaking skills, teaming skills, and problem solving skills and experience. All of these attributes are essential for success in today's, and tomorrow's, workplace.

Our Vision

The ultimate goal of the College is to educate and graduate fully integrated individuals who possess the technical and social competence and confidence to succeed in professional practice and advanced education, to be lifelong learners, and to exercise responsible citizenship.

Methodist College of Engineering & Technology