I implemented this circuit stripboard layout but when I connected this device to phone, there is no pulse in phone reciever. Please notify me what am I doing wrong!!

enter image description here

And here is my implementation picture. The 2 wires on the right are for output from my implementation to the phone. http://imageshack.us/photo/my-images/820/pict1868s.jpg/

The wires on the left are connected to the phone line that is input from the service provider to my circuit. http://imageshack.us/photo/my-images/18/pict1869v.jpg/

Please please help me. Please tell me what is wrong in this implementation. I would be very thankful.

edit: Here is the picture of the bottom. I made sure that the lines and connections are not short column wise. It may look that they are short in the picture but they are not! http://imageshack.us/photo/my-images/403/pict1870f.jpg/

I measured the voltage across all components in this circuit, But I was astonished that telephone line(Service provider line) has 50V DC and my input wires which are connected to service provider wires are just providing 4.86V DC to the circuit. I am using CAT 5e wires for input and output. The voltage across every component is 4.86V DC except the voltage across the transistor and 220 Ohm is 4.01 V DC. Now please somebody help me.

  • \$\begingroup\$ Do you have a multimeter? \$\endgroup\$ – markrages Jun 18 '12 at 18:16
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    \$\begingroup\$ Please show also the bottom of your board. \$\endgroup\$ – markrages Jun 18 '12 at 18:16
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    \$\begingroup\$ Don't connect to the phone line if you don't know what you are doing. You can mess up the phone service. \$\endgroup\$ – Brian Carlton Jun 18 '12 at 20:00
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    \$\begingroup\$ @Brian - I would be more worried about myself; if there's an incoming call (ringing) when you hold the wires you're in for a nasty shock. \$\endgroup\$ – stevenvh Jun 19 '12 at 13:48
  • \$\begingroup\$ Can you Please figure out the problem now? What can be the issue that there is no pulse in phone reciever and upon dialing the phone number I get Phone busy response..Please Help. \$\endgroup\$ – Umer Farooq Jun 19 '12 at 13:52

One thing I noticed is that you seem to have missed out the breaks in the rows as shown in the diagram. In the diagram they are at A8, D9 and G7. You need to cut the copper at these points.

Check all your diodes have the correct polarities and your transistor is the right way round.

Also the soldering looks very iffy, it's possible you have a dry joint or two. I would reflow the joints that don't look shiny and smooth (I'm assuming you are using lead based solder)
Do you have any flux? If so use plenty. Make sure you keep your iron tip clean by wiping it between uses.
Keep in mind that getting this wrong may land you in trouble with the phone company, or possibly worse if you get it right ;-)
It may be better to start off learning with a simpler and "safer" project.

  • \$\begingroup\$ I did the way you told to break the connections but still there is no pulse in phone. I don't know why is this happening please help me. And this is a project I am not trying to unvail someones privacy through these things.. :) \$\endgroup\$ – Umer Farooq Jun 19 '12 at 11:27
  • \$\begingroup\$ Unfortunately, it's hard to be exact with the information provided. It could be a number of things - if you have a multimeter then test for any shorts/opens and check voltages at each node (post results) Do you have the link to the original project page? The warning was more to do with the phone company if you accidentally short the lines or something - also RF interference from the circuit could cause issues, so make sure you use a suitable frequency/power level. \$\endgroup\$ – Oli Glaser Jun 19 '12 at 14:31
  • \$\begingroup\$ hackedgadgets.com/2006/04/30/telephone-listening-bug This is the link to the project website \$\endgroup\$ – Umer Farooq Jun 19 '12 at 14:45
  • \$\begingroup\$ I figured out that the resistance across every component is 48K Ohm, and resistance across across 330pF,470pF and transistor is 60.5k Ohm. Is this normal? \$\endgroup\$ – Umer Farooq Jun 20 '12 at 5:35
  • \$\begingroup\$ If you mean across each individual component then no (if not then at this point it would be a good idea to measure everything - without power applied). You are either measuring incorrectly or your multimeter is damaged. I don't think the phone line voltage should sag under a 50K load (you can try a resistor of this or similar value on it's own across to see) so something else is probably wrong. \$\endgroup\$ – Oli Glaser Jun 20 '12 at 10:07

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