On Thu, Jan 19, 2012 at 5:08 PM, Viesturs Lācis <viesturs.la...@gmail.com>wrote:
> Hello, folks! > > I would appreciate some advice or insights, what am I doing wrong. > > What I want to do is to switch on and off a power to laser engraver diode. > It needs 12 VDC supply and it consumes ~1 A currrent. > > Here is schematics of what I currently have: > http://picpaste.com/DSCF6164-vX7heUEq.jpg > > The problem is that it is not working: > Voltmeter was showing +12 VDC on both leads, going to laser module all > the time, regardless if I had turned the output pin "true" or not. > > What is the voltage of the 'low' state? could it light up the LED? As Steve said, your resistor is in the wrong place. I'd put it on the collector of the phototransistor.; then, the base current of your power transistor would be (12V-0.7V-0.7V)/R; assuming the power transistor beta is 20, you'd need 50mA, i.e. the resistor must be 200 ohm. ------------------------------------------------------------------------------ Keep Your Developer Skills Current with LearnDevNow! The most comprehensive online learning library for Microsoft developers is just $99.99! Visual Studio, SharePoint, SQL - plus HTML5, CSS3, MVC3, Metro Style Apps, more. Free future releases when you subscribe now! http://p.sf.net/sfu/learndevnow-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
