Jump to content
Electronics-Lab.com Community

Re: Free Schematics for electronic surveillance


atlanta

Recommended Posts

  • 1 year later...

  • 7 years later...
Guest JimDiGriz65

I realize this is a very old posting, but wanted to resurrect this thread instead of starting a new one.

The old narcbug website is now at: www.bugplan.com.

I has some excellent circuits -- and the only crystal controlled VHF transmitters I've run across.

Link to comment
Share on other sites

These are the faults I found:

The timer is described in the parts list as ‘a standard NE555 timer chip’. It is powered by 2 x 9V batteries. But that is the absolute maximum voltage rating for many of these chips, and exceeds the 16V absolute maximum of a Fairchild or Contek NE555.

R4 is shown shorted out so Q2 is switched hard on during the 0.2sec pulse. It cannot oscillate under those conditions.

The circuit shows on its legend ‘Page 1 of 3’, so perhaps there is more. Certainly, I would have expected to see a recommended layout to prevent possible interaction between the various inductors.

EDIT: My previous statement about  problem with 555 output going high was not valid, so is now removed. I have now found details of the 555 circuitry. When output pin3 is high (sourced) and its load is connected to a voltage higher than its source voltage, the output goes O/C.
Sorry about that :-[

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...
×
  • Create New...