<html><head></head><body style="zoom: 0%;"><div dir="auto">For the low of budget people, if you just need to generate ring you can do so with bits you might have laying around.<br><br></div>
<div dir="auto">You'll need:<br></div>
<div dir="auto">An audio source for 20Hz sine wave, pulsed in whatever cadence you want.<br><br></div>
<div dir="auto">An audio amplifier, I used a Radio Shack PA amplifier for one setup. Doesn't need to be quality, just function.<br><br></div>
<div dir="auto">If the amplifier has 70 volt line out, you can skip the transformer in the next line.<br><br></div>
<div dir="auto">An 8 ohm to 70 volt PA transformer.<br><br></div>
<div dir="auto">A blocking capacitor, steal a RUN capacitor from an induction motor you're not using.<br><br></div>
<div dir="auto">The capacitor isn't strictly needed, but does limit current.<br><br></div>
<div dir="auto">Circuit is audio source > amplifier > 8-transformer-70 > capacitor in series with one lead > telephone.<br><br></div>
<div dir="auto">Be sure and cut the audio when the actor picks up, you don't want to blast his ear with the ring signal. Maybe remove the speaker from the phone.<br><br></div>
<div dir="auto">Experiment to find what works well with your phone and gear.<br><br><br><br></div>
<div dir="auto"><!-- tmjah_g_1299s -->---<!-- tmjah_g_1299e --><br></div>
<div dir="auto"><!-- tmjah_g_1299s -->Jerry Durand, Durand Interstellar, Inc. +1 408 356-3886<!-- tmjah_g_1299e --><br></div>
<div dir="auto"><a href="http://www.DurandInterstellar.com"><!-- tmjah_g_1299s --><a href="http://www.DurandInterstellar.com">www.DurandInterstellar.com</a><!-- tmjah_g_1299e --></a><!-- tmjah_g_1299s --> & <!-- tmjah_g_1299e --><a href="http://www.DurandInterstellar.ru"><!-- tmjah_g_1299s --><a href="http://www.DurandInterstellar.ru">www.DurandInterstellar.ru</a><!-- tmjah_g_1299e --></a></div>
<div class="gmail_quote" ><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><pre class="blue"><br></pre></blockquote></div></body></html>