Re: Help!!!!!!!!
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Sohan Japa wrote:
> I have built the $4 link, but it isn't working!!!!!!!!!!!!!!!!!
> I connect the link to the computer and the little LED light comes on.
> I open up the $4 special software and intilize the serial port. I plug
> in the other end to the calculator. Now the little light is
> flickering(turning on and off). I try to send something, but it doesn't
> work. I try to receive something, it doesn't work. Pleaseeeeee Help
> me!!!!!!!!!! I am using a 25-pin serial connector and a 2.5 stereo plug
> cable. What is the problem here? I have a DVM tester but don't know how
> to test the $4 link.
Well... I've built several of those serial-port link cables. Most
worked, but one of them didn't for some reason. Hmm. Some things you
might check: What is the voltage drop of the LED? It should be around
2.0, I believe. Are your zener diodes working? They should be 4.7v-5.1v
diodes. Also, make sure they're in the right polarity. Did use the
correct value of resistor? If I remember right, it is two 3.3k and one
330 ohm resistor. Oh.. Do you have the right wires soldered to the
correct pins on the DB25 connector? Oh.. How are they connected, anyway?
Soldering would be the most reliable method.. I could scan the DB9
connector that I used and mail the image to you..(I fit all the pieces
inside a DB9 plastic hood).
Good luck!
Greg Hill
ghill@lab.tech.bhs.davis.k12.ut.us
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