Technician Electronics

10 Feb

1972 I got a chance to work as a Laboratory Technician for Industrial Electronics Lab of a Polytechnic Institute in Mumbai, India. During interview then principal of the institution and the department head was surprised with my knowledge, experience and approach of the subject. The line of duty was to assemble new circuit boards as teaching aids for Lab experiments, repairs of lab instruments and help the students and teaching staff to solve the day to day practical problems.I had prepared many practical application circuit boards by use of Audio, Pressure, Heat and Movement sensing devices to operate day to day appliances.

1 – In the first month I had made a 4 stage process sequential timer, using Vacuum Tubes, Relays, R/C variable timing control on a 3 X 2 feet Bakelite board as teaching aid.

2 – I had drawn a big circuit on a 3 X 2 feet Bakelite board, assembled the components, made working oscilloscope to teach use of each component. Provided special switches to switch off certain component to create usual defects caused by failure of a component.

3 – assembled / made a wireless variable positioning remote control device using stepper motors.

4 – assembled / made  single phase / three phase motor control circuit board using Thyristors and Triacs to explain the functionality in the practical environment.

During first annual practical exam of second year students, by rule I should not attend any student yet I was called by the external examiner to find out the cause of unusual current readings of photo cell in total darkness.  That photocell experiment was tried by seven more students, every student had almost same readings. While checking the readings of the 8th student examiner had some doubts. There was a silly practical mistake that made every one laugh. See the fig.

On one occasion I was asked to give my advice to a question, never tried by any one in last four years, though it was asked to solve in every exam. The final year students were preparing for final exam, the concerned lecturer told them about this unsolved question. The question was “explain and make block diagram to check the speed of a fired bullet.” I had given them some clue by following method, using dual beam oscilloscope. Two sensing devices or  switches, one at the gun trigger and second at the target. connected to the dual beam oscilloscope. Two beams would show the time difference between two spikes.

5 – 1974 color TV transmission started in Mumbai, that Institute started a TV Technician course. I made a functional teaching aid circuit on a 4 X 3 feet Bakelite board.

I did enjoy my three years in that institute, had valuable knowledge by reading theory books as a staff member. But one topic made me doubtful about those books. I was searching for a solution to find out the value of a coupling capacitor in two amplifier stages. Book A was giving reference to book B, that referred to book C, till book M. I got frustrated at the end of 5th day when I saw book M referred to book A. In reality I was simply selecting a capacitor in a minute by checking the output of the previous stage, should not cause a drop in the total output and should not create a time delay for next stage of that amplifier.In this institution one incident made me proud to prove my ability and sad as well to know the lack of human values even in educational institutions.

A defective instrument was brought to that electronics lab, there was no documentation of that unit, only the operator explained how it was working as a device controlling the surface accuracy of crank shafts. Without any help, not a single person in my department helped or given guidance, I prepared the circuit diagram of that device in just two days and on third day made it fully functional. There were 6 stages of comparator circuits with variable selection control. There was a defective transistor pair in one comparator stage. That client paid 25,000 rupees to that institute as repair charges. This was a proud moment for me.

But the distribution of that amount was very sad for me because it was shared by many as per seniority and post, I was paid only 250 rupees. All others who shared that amount had more share than me. When I inquired this injustice to my efforts. My shameless Department head told me ” Bigger fish eat smaller fish, you have to learn the law of nature”. I was furious “this law of nature is true for animal world, I consider my self a human being and expect to be treated as human in this educational institute, sorry no know I am in the animal world.”

I used images from Google image search and made my own for photo resistor circuit
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Posted by on February 10, 2011 in Uncategorized


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