Price - Stock No 160

Check your kit


Schematic Diagram

PCB Layout


VOYAGER is a super-sensitive FM Radio microphone developed by Talking  Electronics.  The components are all common types of resistors, capacitors and transistors matched so well in this circuit that  amazing  sensitivity and  distance  are obtained.  The name VOYAGER was given to it "because it  goes so far".  We have re-designed the Board and further matched some components  to  suit  the  needs  of  the  classroom.  The result is a superb bug which is compact but powerful, and quite easy to build.


Check Your Kit

  1. Check the P.C.Board for damage, and check  continuity  of the tracks with a multimeter or circuit tester.
  2. Identify the five resistors either by their colour bands or with a multimeter - a Digital Meter will give a precise reading of  the values of the resistors.  Mount them in their respective places.  You will have  difficulty  in  trying  to  mount  them flat so bend the legs so the resistor leans upwards at an angle to the board, preferably with the  high end  closer to the side of the board, and leaning down towards the centre. Bend the legs sideways on the track side of the board to  stop  them  from falling out.  They can be soldered at any time.
  3. Identify  the  six capacitors by their numbers and mount them in their correct places.  They can be put in  any  way  round.   Push them  down  close  to  the board.  This will improve the stability of your bug.  The soldering is extremely important for success - Refer Soldering Technique. 
  4. The Trimmer Capacitor can be gently pushed into place and soldered off.
  5. Bend the middle leg of each transistor backwards a little to match the holes and push the transistors into place.  Once  again  push them well down to the board.
  6. The three pins are to connect the microphone (2 pins) and the aerial.  The three holes are drilled out larger to take the pins. Push them in and solder.  Also apply a little solder to the end where the wires connect to tin the pins.  The Fig.8 wire has a wire with a white trace.  I  usually  use this as the Positive wire. Strip, tin and solder the wires to the pins.
  7. Study the diagram of the microphone and solder the  metal tag to the Negative pole as shown.  Solder the wires to the poles but make sure the polarity is correct - black/white trace to Positive pole.
  8. Turn  the  board  over  and push the battery holder into position down to the track side of the board.  Check about  how  far  down  you  want  it  to  go, remembering that you need room to get the tip in to solder the legs to the track.  Lift the battery holder out  and  heat  the legs  until  you get solder to stick at about where the legs will meet the   board.  Push the holder back into position and solder into place.
  9. Take a piece of 3mm rod.  Hold the winding wire from your   Kit and wind FIVE full turns so the two ends are both pointing down.   The windings  should  be  separated  from  each other by 1 to 2 mm so the ends about match the holes in the board.  Leave the coil on the former and  nip off  the ends long enough to fit through the board.  You will need to take a blade and scrape the plastic/enamel coating off the ends of the coil  so you can solder it in place.


You are now ready to try the bug.  Slip a 9V  battery  into place,  turn  a  FM  radio  on and move the station selector across the dial to find the frequency that the voyager is transmitting.   If you cannot find a signal try spreading the coils  apart.    This  will  increase  the  frequency of the bug.  Try again to find its  frequency.  If it comes on top of an existing  FM  station  adjust  the width  of the coils.  Final trimming can be done by adjusting the trimmer capacitor.

The length of tinned wire is great as an aerial for  tuning the bug and you will find that it will transmit at least 30 Metres with this  setup.  Adjust the receiver aerial to get the best reception.  An aerial wire up to 1.7 Metres will give a range of 200 Metres or more.


 Troubleshooting  consists  of  checking  carefully that all components are in their correct positions.

Careful  positioning  of  components  and  good   soldering technique should give success without any difficulty.  When  you  are  operating  the  bug,  remember that fingers touching components or even near them will alter  the  capacitance  and affect the balance of the oscillator.

A  slide  switch and leads are provided; you may choose not to use it, but if you choose to use the switch, provision  is  made  on the  positive  rail.   There  are  two  unused  (and usually undrilled) donuts. Cut the track between the donuts and connect the wires from the switch to each of the donuts.  Remember  the  switch  is  Double  Throw Double Pole (DPDT) so connect the wires to the centre and one end poles on the same side of the switch.   If  you don,t use the switch so you will have to remove the battery to switch off.  The current drain is  4.6mA  so  a  9V  battery  will  last  about  20  hours,  or an alkaline type about 50 hours.  The advantage of the alkaline battery is that it will hold its voltage high  for much longer and its output does not fall off so quickly.

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