swapping components in circuit - help redesign please!

Discussion in 'General Electronics Chat' started by Delinquent, Mar 22, 2011.

  1. Delinquent

    Thread Starter New Member

    Mar 22, 2011
    Hi all,

    New here, I've done a search for this being covered but I'm afraid I'm a bit of a numpty when it comes to electronics, so may well be looking for the wrong thing! Basically, I found a schematic for a trigger on the web, that uses a IR emitter and receiver, which when the beam is broken triggers an output from an SCR.

    Only problem is, that I want to use the circuit with a sensor I already have, which doesn't allow me to build the circuit "as is" - so I was hoping that someone could help recreate the circuit based around my sensor cable.

    This is the circuit I found:


    which has the description: "The circuit shown uses an infrared emitter (XC-880-A) and detector (TIL414). A 2N2222 transistor acts as a switch in the gate-cathode path of an SCR. A sensitive-gate SCR is used. (See Footnote 3.) The SCR is connected either to the terminals of a flash unit or to a delay unit (to be described later). As long as the phototransistor is illuminated by the LED, the collector-emitter path of the 2N2222 is open. When the light is blocked, the voltage across the phototransistor rises and the 2N2222 conducts, thereby gating the SCR."

    The sensor I already have looks like this:


    The +ve -ve and signal being connected to a 3.5mm stereo jack.

    So... can anyone redesign the circuit for me, so that I can just plug my current sensor into it please? If you want to use language fit for an idiot feel free, I make no bones about the fact that whilst I can solder, make PCB's and recognise most of the symbols, I don't really have a clue WHY most of the components are used!!!

    Many Thanks.