LCD Control/Boost/Switching

Discussion in 'General Electronics Chat' started by XerxesX24, Sep 13, 2012.

  1. XerxesX24

    Thread Starter New Member

    Sep 13, 2012
    Hello AAC members.

    Thought i'd join these forums as you all seem like a smart, tolerant bunch. I'm wanting to help where I can and have a few puzzles of my own. ;)

    In short, I have many an old gadget that have low voltage, low power Liquid Crystal Display's. (Nematic Twisted, if my research is correct.)

    EG: Calculators, clocks, old mobile phones and so on...

    My questions:

    What is a typical voltage to polarize a given segment?

    Could I trigger a transistor with said voltage?

    If not, what additional circuitry could I use to trigger a transistor.

    I know that Germanium transistors have a low activation point -- I remember that from a book i've got and building so-called "Joule Thieves".

    I'm trying to go with a low-tech solution (they are more fun and i'm not properly equipped to meddle with microcontrollers etc) involving scaling and several arrays of transistors. All will become clear if I eventually get around to building the damn thing!

    Any help much appreciated.
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    Last edited: Sep 13, 2012
  3. XerxesX24

    Thread Starter New Member

    Sep 13, 2012
    Thanks for the reply and the info.

    I'm not trying to make the LCD work -- it's already in an operational state.

    My aim is to "sense" the voltage leading to each segment somewhere on the pcb after the control IC's or alternatively on the ribbon cable. I'm not going to try and get some connections via the conductive rubber strip -- those things are a menace!

    With that so-called "sense" I want to be able to trigger other circuits parts via transistors.

    A scalable led timer, harvesting it's timings on/off via any given segment through a transistor. Using the basic clock and everything from a small lcd clock. Except not using any IC's.

    Transistor/led/power banks would be scaled up once it was reliable and I was going to make an unusual clock with it.

    I know it would likely be many, many components. But.. I like a challenge!
    Last edited: Sep 13, 2012
  4. XerxesX24

    Thread Starter New Member

    Sep 13, 2012
    Is any of that understandable? It makes perfect sense to me! haha

    Also.. I am a tit, if i'd looked up a small LCD driver I could have discovered the voltages involved.

    I'm getting mixed messages here though. I've now read several reports that give widely varying voltages. From 0.2 to 2.8v

    Do they really vary that much from one basic lcd to another?