Car Radios

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Car radios are excellent receivers for detecting meteors. They are:

designed to reject interference caused by the car engine
sensitive to radio signals in order to pick up distant stations while travelling
inexpensive to acquire when sourced from auto wrecking yards
most car radios manufactured in the last 15 years are digitally tuned

With a few modifications they can easily be used for detecting meteors.

We have tended to use Chrysler radios and know some of the quirks involved with using them. Other makes may work as well. Here are some of the modifications required to set up your system.

Pictured here is a Chrysler radio model 4469088, front and rear view. The back of the radio is where all the connections and modifications are made so it will work as a radio meteor detector. All digital car radios have similar pin connections although they are arranged in different configurations.

The pieces that need to be added to the car radio are:

a 2000 ohm resister (color bands are red, black, red with a possible 4th color that can be ignored)
a 1/8" mono type headphone jack
a 1000 mf (microfarad) electrolytic capacitor rated for 25vdc (can also be a 16 vdc rating)
a 12 vDC adapter rated at 800 ma (milliamperes). Five hundred milliamps can be used but we recommend 800. This converts the 110 volt Alternating Current (vAC) from wall outlets to 12 volts Direct Current (vDC) current that will power the car radio.
2 meters of double stranded wire to fasten the headphone jack to the radio. The headphone jack will eventually be connected to the "line" jack on the computer sound card.

Make the connections to the radio using a soldering iron. Note that the one lead (marked "B+" on the diagram) of the DC adapter connects to both of the last two pins on the right hand set of pins on the back of the radio. The wire marked "+" on the electrolytic capacitor connects to the 3rd pin from the left on the right hand set of pins. The adapter wire marked "B-" on the diagram should connect to one of the screws on the back of the radio. This is called the "ground." One wire from the resistor, and one from the audio jack should also connect to the ground. The other wire on the resistor connects to the negative lead (wire) on the capacitor and to the other wire from the audio jack.

  This picture shows what is called a "Motorola Jack" named after the company that designed and makes these cable connectors. The circle on the top left hand corner of the rear of the radio is where this jack goes. But first, you must attach it to the end of the coaxial cable coming from the antenna. Before your system will work properly, you must insert the jack into the antenna connected at the top left corner in the back of the radio.

Follow this link to see how to operate the radio for detecting meteors.

 

Copyright 1999-2015 by Sky Scan, Edmonton, Alberta, Canada. 

We gratefully acknowledge the financial support of the 

Edmonton Centre of the Royal Astronomical Society of Canada, Department of Physics (University of Alberta)

and the

Natural Sciences and Engineering Research Council of Canada

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