<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">John, Were you able figure it out the circuit from the website? I breadboarded one last night (just for the heck of it) One thing - it seems that ambient temperature effects the timing by maybe 20%. Other than that it worked well. I also was NOT using a low-leakage type cap like a tantalum or NPO that the website mentions. They will give you better results with long duration timings. Also I would look at using the 7556 cmos chip or the TLC556 if your running from battery; I also think they have better thermal stability. Let me know if you want the schematic.<DIV><BR class="khtml-block-placeholder"></DIV><DIV>In case the link I gave you before didn't work try this one:</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><A href="http://www.electronics.dit.ie/staff/mtully/555%20folder/555%20timer.htm">http://www.electronics.dit.ie/staff/mtully/555%20folder/555%20timer.htm</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>For some reason the link I passed to you didn't work when I tried to go to it but the one above works.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>-John</DIV><DIV><BR class="khtml-block-placeholder"><DIV><BR class="khtml-block-placeholder"></DIV><DIV>On May 24, 2007, at 5:14 PM, John wrote:<DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"> John Scherer wrote:<BR> <BLOCKQUOTE type="cite" cite="mid16E9B630-5E5E-480A-9DA1-9B7C3C167F52@schererzoo.com">I haven't played with the 555 for a long time but basically you want a 556 chip. The first chip is configured for Astable operation and its output is feed to the second timer which is configured for Monostable mode. <DIV><BR class="khtml-block-placeholder"> </DIV> <DIV>See this site:</DIV> <DIV><BR class="khtml-block-placeholder"> </DIV> <DIV><A href="http://www.electronics.dit.ie/staff/mtully/555%2520folder/555%2520timer.htm">http://www.electronics.dit.ie/staff/mtully/555%20folder/555%20timer.htm</A></DIV> </BLOCKQUOTE> <BR> Thanks<BR> <BR> John<BR><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">aprssig mailing list</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="mailto:aprssig@lists.tapr.org">aprssig@lists.tapr.org</A></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig">https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig</A></DIV> </BLOCKQUOTE></DIV><BR></DIV></DIV></BODY></HTML>