I'm doing a school project now that uses an open frame solenoid to automatically open a drawer. I need help for the driver circuit for the solenoid. Can you pls give me some suggestions....

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it depends upon how much current the solenoid will draw

 

the solenoid is an open frame 12V DC solenoid. can u pls give me some specifications and descriptions about the NA51 transistor?

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u said only 12v , what about the resistance of that?
i'm sorry is didn't find anything for na51.. what r u going to do with it?

 

NA51 NPN 40x 45v 2.5MHz 4A (TO-220)
You will need a diode across the solonoid or the transistor will zap.

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my project is a pc interfaced mini automated library using the parallel port. It consist of ten drawers which will automatically open (using solenoid to unlock the lock) once selected. I need some suggestions on what type of decoder will i use? Parallel Port-Decoder-Solenoid Driver-Solenoid-Drawer.

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I think the parallel prost has 10 ouputs so you can just wire it up directly to it.

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i'l be using only the data output of the parallel port, D0 to D7.

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ouput muliplexer?

It only needs two pins(clock and data)

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Since you don't have 10 outputs, use Do thru D3 in BCD and use a CD4028 BCD to decimal decoder, or 74145.

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just wanna ask, if you know what decoders generate logic high outputs

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The CD4028 has logic high output, the 74145 has logic low (open collector) output.

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i need some suggestions on how to connect the sensor circuit of my project to the parallel port. The sensor will serve as an input, everytime the sensor is cut, it will update the database. There are 10 sensors.

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so ur sensor will(should) output 0-5V , connect it to the standard i/p pins (10,11,12,13,15) of the LPT , if u r using dos/linux+c/c++ , an inportb will get the pin status.
for 10 sensors u need to multiplex the data.
refer http://www.lvr.com/parport.htm

 

yes the output of my sensor is 0-5V. I'm using visual basic for the interfacing. can i use encoder for the 10 sensors?

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