<div dir="ltr"><div><div><div><div><div>The 1.5A is not the whole story; you can watch this: <a href="https://www.youtube.com/watch?v=8ruFVmxf0zs">https://www.youtube.com/watch?v=8ruFVmxf0zs</a><br></div>Basically, if you had that 7805 on free air powering your two relays, it would (try to) reach about 170°C above ambient temperature. The PCB is a nice heatsink, but it is shared with the big GSM regulator, and that rises the temperature too.<br>
</div>By all means, experiment!! The 7805 has thermal protection, and you should test your circuit on the bench keeping a finger on the IC to feel if it gets too hot.<br></div>You should take care of the increased ripple too, but a small cap should do the trick there.<br>
<br></div>Regards<br></div>MG<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-06-16 23:09 GMT+02:00 Olav A. Antonsen <span dir="ltr"><<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div link="blue" vlink="purple" lang="NO-BOK"><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">I got some help from a user on a Norwegian forum who pointed me to <u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><a href="https://raw.githubusercontent.com/openvehicles/Open-Vehicle-Monitoring-System/master/vehicle/Car%20Module/v2-base/OVMS_V6A.pdf" target="_blank"><span style="color:#1f497d;text-decoration:none">https://raw.githubusercontent.com/openvehicles/Open-Vehicle-Monitoring-System/master/vehicle/Car%20Module/v2-base/OVMS_V6A.pdf</span></a><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">Looks like a 7805-regulator is supplying the OVMS module with +5V @ 1.5A max.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><a href="https://www.sparkfun.com/datasheets/Components/LM7805.pdf" target="_blank">https://www.sparkfun.com/datasheets/Components/LM7805.pdf</a><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">80mA won't be a problem then.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">--Olav<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><u></u> <u></u></span></p><div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">Fra:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> <a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a> [mailto:<a href="mailto:ovmsdev-bounces@lists.teslaclub.hk" target="_blank">ovmsdev-bounces@lists.teslaclub.hk</a>] <b>På vegne av</b> Mastro Gippo<br>
<b>Sendt:</b> 16. juni 2014 23:03<br><b>Til:</b> OVMS Developers<br><b>Emne:</b> Re: [Ovmsdev] OVMS - HW<u></u><u></u></span></p></div><div><div class="h5"><p class="MsoNormal"><u></u> <u></u></p><div><div><p class="MsoNormal">
It may be a problem to get the 5V from the output of the regulator, but the nice thing about that module is that it is isolated; you can connect your own power supply and be 100% safe. These relays draw about 80mA each (just tested them, I have the same product at home), so if you turn them on one at a time and for short periods of time it should be ok (I don't know a lot about the termal design of the OVMS).<u></u><u></u></p>
</div><p class="MsoNormal">MG<u></u><u></u></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt"><u></u> <u></u></p><div><p class="MsoNormal">2014-06-16 22:37 GMT+02:00 Olav A. Antonsen <<a href="mailto:olav@ansit.no" target="_blank">olav@ansit.no</a>>:<u></u><u></u></p>
<div><div><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Hello</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">My knowledge of electronics is limited.</span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">As far as I understand the OVMS module is supplied with +12V via the OBD connector. What I don't understand is where the +5V comes from? </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><a href="https://github.com/openvehicles/Open-Vehicle-Monitoring-System/blob/master/vehicle/Car%20Module/v2-base/20120814-boarddesign.pdf" target="_blank">https://github.com/openvehicles/Open-Vehicle-Monitoring-System/blob/master/vehicle/Car%20Module/v2-base/20120814-boarddesign.pdf</a></span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">I'm currently trying to control a relay using the RC3 output on the PIC18F2580 as a control signal to a rely on a relay module</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"><a href="http://www.dx.com/p/arduino-2-channel-relay-shield-module-red-144140#.U59Qavl_t8E" target="_blank">http://www.dx.com/p/arduino-2-channel-relay-shield-module-red-144140#.U59Qavl_t8E</a>.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">The relay module needs to be supplied with +5V to drive the relays, and my plan was to get the +5V from the OVMS module using pin 13 on the HEADER 9X2.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">But I'm afraid I might blow something on the OVMS module if the relay module draws to many mA.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><u></u><u></u></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">Any advice would be appreciated.</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><span style="color:#888888"><u></u><u></u></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US">--Olav</span><span style="color:#888888"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d" lang="EN-US"> </span><span style="color:#888888"><u></u><u></u></span></p></div></div></div><p class="MsoNormal" style="margin-bottom:12.0pt">
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