Jump to content
Electronics-Lab.com Community

Help!! My Door Alarm is not work?


michael1983
 Share

Recommended Posts

Help..
Im doing my electronic course project...
Im choosing the door alarm project from this site.

http://www.electronics-lab.com/projects/sensors/020/index.html

1. There inductor 1 must be in 20 to 30 turns? it dont care how long the wire diameter we use?

2. the miniature inductor there is counting in mili or micro henry??

3. If i trying my circuit in breadbroad (solderless circuit board), it may be not work???

:(

Link to comment
Share on other sites


1. There inductor 1 must be in 20 to 30 turns? it dont care how long the wire diameter we use?

The instructions say the wire diameter to use and says exactly how to make it.

2. the miniature inductor there is counting in mili or micro henry??

The instructions say 10mH which is ten milli-Henries.
Micro-Henries is written as uH.
3. If i trying my circuit in breadbroad (solderless circuit board), it may be not work???

Most radio frequency circuits like this one do not work on a breadboard because the stray capacitance and stray inductance are too high.


Link to comment
Share on other sites



There inductor 1 must be in 20 to 30 turns? it dont care how long the wire diameter we use?



Michael,
More specifically, L1 is made by wrapping (coiling) the wire around R2 until it is completely covered with the winding. This is why it says 20 to 30 turns. Different resistors will be different lengths and thickness.

MP
Link to comment
Share on other sites

oh..ok...

Sir,

1. the 10 mH inductor is so hard to get at my place here...is the size is same like other inductor in green color like resistor?

2. this site is from which country?

3. can i buy component online??

4. any other circuit recomend oscilator circuit..better can try in breadboard....

thank you.. ;)

Link to comment
Share on other sites


1. the 10 mH inductor is so hard to get at my place here...is the size is same like other inductor in green color like resistor?[/quote[
A 10mH miniature inductor is available in electronic parts stores and online.


The owner is Greek but the site has members from all over the world.


I usually order electronic parts online. If i place an order before 8:00 PM then it is delivered the next morning. I usually order from www.digikey.com but there are hundreds more sites.
Link to comment
Share on other sites

The parts are too far apart on your pcb. The wires to the switches and trimpot are much too long. The distance between parts and the long wires adds too much stray capacitance and inductance which is not wanted in this radio circuit.
Check the datasheets for the transistors to see if you connected their pins backwards.

Link to comment
Share on other sites

I think your circuit doesn't work because the pcb is too big.
Radio circuits like this one must be small so that stray capacitance and stray inductance are small.

My soldering iron is temperature controlled so that it never gets too hot. A solder joint takes only 2 seconds so the parts don't have enough time to heat much.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...