Adept Rocketry - SB20 Instructions and Data Sheet

Small Sonic Location Beacon™ (Beeper)

Copyright © 1989-2011, All Rights Reserved

SB20 Sonic Location Beacon™ Price: $24.95 - Includes GP-23A Battery.


The Model SB20 Sonic Location Beacon™ is an audible beeping device that may be used to help locate model rockets, model airplanes, payload carrying balloons, and so on. This device creates repeating 3600 Hertz patterned beep tones at a volume of  95 decibels. The device has a mute system that may be used to silence the beacon until takeoff, or until deployment of the parachute. In the silenced mode, the beacon will run for a week on a fresh battery, which means that you need not be concerned about how long the rocket sits on the launch pad. When beeping, the battery life is in excess of 24 hours, so you'll have plenty of time to look for a lost rocket or payload.

With some designs it is common to use more than one sonic beacon in the same rocket. Many rockets are designed to separate into two or more sections for recovery, such as with a system that normally ejects a payload which has its own parachute. A second sonic beacon can be installed in the payload section.

The SB20 measures 0.9" wide by 0.63 thick by 2.7 long. Its weight with battery installed is only 0.6 ounce, and it fits inside a tube with a minimum ID of 1.01 inch. It will operate mounted in any orientation. This device runs on a 12-volt alkaline lighter battery, and it can be heard from a distance of over 100 yards.


Install a 12-volt alkaline lighter battery (GP-23A, Eveready Energizer No. A23, Radio Shack 23-144, etc.) in the battery holder. The beacon will start operating. To reduce the sound while testing, hold a finger over the sound port, or use a small piece of tape or reusable putty temporarily. Secure the battery in the holder with nylon string (not wire). Wrap (and tie) the string diagonally over the battery, through the holes provided, and across the back of the circuit board. Waxed Dental Floss works very well for this purpose. After the battery is installed and the securing string is in place, a convenient way to temporarily turn off the unit is to slip a small strip of paper or thin plastic between the positive end of the battery (opposite end from spring) and the inside positive end of the battery holder. This approach for powering down the beacon may be used for an indefinite period of time.

The SB20 is equipped with a small socket connector that allows the unit to be put into a muted standby mode. Connect a small wire jumper between the two connections of the small socket connector to put the device in standby. This will mute the sound, and the current consumption drops substantially. The jumper wire should be very thin. Wire wrap wire and the thin steel wire salvaged from a spent Estes igniter both work very well. Form the wire into a short loop. If string is used as the arming mechanism, slip the string through the wire loop (tie in place), then insert the two ends of the loop into the two contacts of the connector.

 When the jumper is pulled free, the unit goes into operational mode. The jumper can be pulled free with a simple string that pulls when the rocket separates, or by deployment of the parachute. Some other options for activating the device are:

A small weight could pull the jumper free on the first acceleration of liftoff.

A small shorting switch could be wired to the connector, and when the switch opens, the beacon would start operating.

The switch could be held closed by contact with the launch rod.

The switch could be held closed until stage or section separation.


Sound Level (measured at 12 inches): 95 db typical.

Beep Tone Frequency: 3.6 kHz nominal. Pattern: 2 quick beeps every 2.5 seconds.

Operational Current Consumption: 1 mA nominal. Standby Current Consumption: 0.1 mA nominal.

Operational Battery Life: one day minimum. Standby Battery Life: one week typical.


This device may be mounted in any orientation. Holes in both ends of the circuit board allow the device to be secured with #2 screws, standoffs, and hexnuts, or with string or wire. A Muting Jumper (small loop of wire) installs in the small socket connector. A weight connected to the loop could pull it free on rocket takeoff. Or a string connected to the loop could pull it free on parachute deployment, or when stages or sections separate. The picture above shows one handy way to rig any Adept Rocketry Beeper, small or large.

This device fits inside a tube with a minimum ID of 1.01 inch. It may be mounted inside any open-ended section of a rocket. Or it may be mounted and secured inside a short section of tube (see Data Sheet for SB1) of its own for protection (and so the circuit board won't snag on anything), then the entire Beeper/tube assembly can be ejected along with the parachute. Just connect the assembly to an appropriate point on the shock cord or parachute line, or it may have its own section of shock cord which is connected to the parachute system.

Mounting holes are provided at each corner of the circuit board to allow mounting with screws, standoffs, and hexnuts. Also, the device may be secured with string or wire. The holes can also be used as tie points for the parachute cord or shock cord. In small rockets the device can even be mounted in line with the cord, with the parachute connected to one end, and the shock cord connected to the other end. The beacon can be mounted in the base of the nosecone, or in the top section of the rocket near the separation point. In any case, it must be located near an opening to the outside for loudest sound. In some cases it's even possible to amplify the sound by adjusting the mounting position and letting the tube act as a sound chamber.

The beacon may be secured to basswood or plywood pieces that are connected to bulkheads or other structural components. In larger diameter rocket tubes the device can be mounted in a smaller section of tube (that has a sealed bottom) and secured in the parachute area of the larger tube. The parachute (and wadding if any) would fit into the remaining area beside the beacon's mounting tube. Care must be taken to assure that the parachute (and wadding) will still deploy properly. Note: the higher the device is mounted in the vehicle (CG closer to nose end) the more it adds to overall vehicle stability.


Adept Rocketry and Adept Instruments, Inc. warrant to the original purchaser that this product is free of defective parts and workmanship and that it will remain in good working order for a period of 90 days from the date of original purchase. This product will be repaired or replaced within 90 days of purchase if it fails to operate as specified, if returned by the original purchaser and if it has not been damaged or modified, or serviced by anyone other than the manufacturer. Adept Rocketry and Adept Instruments, Inc., their owners, employees, vendors and contractors shall not be liable for any special, incidental, or consequential damages or for loss, damage or expense directly or indirectly arising from customer’s or anyone’s use of or inability to use this device either separately or in combination with other equipment, or for personal injury or loss or destruction of other property, for experiment failure, or for any other cause. This device is sold as an experimental accessory only, and due to the nature of experimental carriers such as rockets, the possibility of failure can never be totally removed. It is up to the user, the experimenter, to use good judgment and safe design practices and to properly pretest the device for its intended performance in the intended vehicle, or reasonable facsimile of same, under controlled conditions to gain reasonable belief that the device and vehicle will perform in a safe manner, and to assure that all reasonable precautions are exercised to prevent injury or damage to anyone or anything.

WARNING: Do not use this device unless you completely understand and agree with all the above statements and conditions.

SB20 Small Sonic Location Beacon™ Price: $24.95 - Includes GP-23A Battery.

Additional GP-23A Alkaline Lighter Battery; Price: $2.25.

GP-23A50 Alkaline Lighter Batteries (box of 50 at 50% Discount); Price: $56.25.      12/26/11