Summary
Information on increasing the volume of the IS-RS ringtone using an external speaker.
Solution
The IS-RS outputs about a 0.5 W, which may not be enough for noisy applications. A self-amplified speaker will need to be used, wired to the SP and SE terminals. This will also require a resistor placed in series with the amplified speaker. The resistor can range from 4.7K to 10K ohms, 0.25 W. The resistor will go in series with one leg of the speaker as seen below.
