• Question: Give me an example of a time when you applied your ability to use analytical techniques to define problems or design solutions?

    Asked by lewisjeffries15 to Graham, Luke, Maksim, Ruth on 20 Jun 2014.
    • Photo: Graham Wiggins

      Graham Wiggins answered on 20 Jun 2014:

      lewisjeffries15 – good quesion !
      I had to work out a way of getting a very low power 5v signal to work on something that expected to recieve a powerfull 24v signal.
      Looking in the catalogues/interweb showed me nobody makes something to do that “out of the box”
      so, I thought a little “sideways” and used 2 amplifiers….
      one to increase the power of the signal. that used an op-amp with “unity gain” = feedback of 1, a so-called “voltage follower circuit.
      That fed into another op-amp, with a fixed gain, to increase the voltage of that signal to 24v.

      I could have used other techniques, though as I had a timescale, and am comfotable with op-amps, it was the way for me to go. Having a pile of the required op-amps helped as well 🙂 saved waiting for parts to arrive. Icould have used a transistor pair to achieve same results, or an opto-isolator, or some fancy logic gates with “pull up” resistors.
      Op-amps were quick, easy + also understand-able for repair in a few years time by someone else.

    • Photo: Maksim Schastny

      Maksim Schastny answered on 22 Jun 2014:

      I am currently working on a faulty data acquisition board which has a short circuit. The board has aver 1500 components and finding short circuits is a big challenge.

      Firstly, I have used my Digital Multimeter and tested for resistances following they circuit diagram.

      After that I have used half split method and divide board in to halves and de-soldered power supplies to each rail in order to find out if it was just one power rail that went short circuit. However, that proved to be no use.

      I have moved on to use short locator device which helps you to find short circuits by scanning each area of the board with a special probe. The device directs you with arrows on the screen to a potential fault area. However, the device failed to locate the fault.

      Moving on, I have used thermal camera in order to see where the fault might be. In short circuit scenarios, when current is applied the faulty components will heat up and stand out on the camera. I have managed to locate two chips which were unusually hot and on Monday I will investigate them in more detail.

    • Photo: Luke Fry

      Luke Fry answered on 24 Jun 2014:

      Well…I do that mostly every day but one example would be when I had to determine how thick a piece of glass needed to be to withstand the pressure on it. I first used a quick hand calculation and then produced a 3D CAD model of it and used ANSYS (a computer program used to calculate all manor of things including stresses, thermal, magnetism, explosions…etc) to check that my hand calculation was correct. It was, the glass needed to be 5mm thick, including a BIG Factor of Safety.

    • Photo: anon

      anon answered on 24 Jun 2014:

      i have to use analytical techniques to correctly work out the weight of a bridge so that i know how to demolish it safetly.

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