felto Posted January 28, 2005 Report Share Posted January 28, 2005 Has anyone ever heard of this switch?It looks like a 'U' shape and has four terminals to it soldered to the circuitboard. In betweenthe 'U' shape is a grove where something blocksthe optics and I guess that it turns it on or off.My question is does anyone know how to measure this with a voltmeter? I know there are diodesinside to measure for .6 volts or something butcan someone tell me which terminals to testand what readings should I get. Thanks in advance Quote Link to comment Share on other sites More sharing options...
MP Posted January 28, 2005 Report Share Posted January 28, 2005 Felto,Perform a search for opb optical switches. Here is a link to an application note:http://www.optekinc.com/pdf/App%20Note%20213.pdf#search='opb%20optical%20switch'One side has an LED and the other side has a photo transistor. Making or breaking the light path turns the transistor on or off. They are good for indicating that something is moving or to measure RPM when used with a slotted wheel.MP Quote Link to comment Share on other sites More sharing options...
felto Posted January 28, 2005 Author Report Share Posted January 28, 2005 Thanks Do you know how to test a voltage regulator?I have a 7812CT 3-pin voltage regulatorand I think its bad. Can you tell mewhat pins are what and how to testit with a voltmeter? Its for a multiprintergizmo and when I hook up the power it sparksback and I get no juice from it. Thanks again for your help Quote Link to comment Share on other sites More sharing options...
MP Posted January 28, 2005 Report Share Posted January 28, 2005 Felto,This is a new subject. You should start a new topic or others might not read your question.Here is the data sheet for the 7812. It has the pin out and the electrical characteristics. Basically, the middle pin is ground and the right pin is the 12 volt output when you give the left pin enough voltage. Please see the data sheet to make this more clear.MPLM78XX.pdf Quote Link to comment Share on other sites More sharing options...
felto Posted January 28, 2005 Author Report Share Posted January 28, 2005 but can I test the leads just like I wouldtest a diode? Quote Link to comment Share on other sites More sharing options...
MP Posted January 29, 2005 Report Share Posted January 29, 2005 For this type of testing. everything in the circuit will effect the readings unless you pull the device and test it. This is not necessary. If you lift pin 3 to insure something else in the circuit is not pulling down the voltage, and then you measure 14.6 volts or more between pins 1 and 2 but do not measure 12 volts or close between pins 3 and 2, I would suspect a bad voltage regulator. However, if you do find 12 volts between pin 3 which is lifted and pin 2, the ground, then something else in the circuit is pulling down the voltage.Note: Power should be turned off while you are desoldering the pin. Then turned back on for the test.MP Quote Link to comment Share on other sites More sharing options...
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