Date: Wed, 6 Jul 2011 22:40:08 +1000 (EST) From: Ian Smith <smithi@nimnet.asn.au> To: Achilleas Mantzios <achill@matrix.gatewaynet.com> Cc: Chris Hill <chris@monochrome.org>, freebsd-hardware@freebsd.org Subject: Re: FreeBSD and controlling an alarm via relay Message-ID: <20110706212809.O84785@sola.nimnet.asn.au> In-Reply-To: <201107061249.49637.achill@matrix.gatewaynet.com> References: <201107041339.22470.achill@matrix.gatewaynet.com> <201107051730.03784.achill@matrix.gatewaynet.com> <20110706170845.Q84785@sola.nimnet.asn.au> <201107061249.49637.achill@matrix.gatewaynet.com>
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Hi Achilleas, Dropping multimedia@ cc as this seems pretty well 100% hardware .. but I'm not subscribed to hardware@ so please cc me from there. On Wed, 6 Jul 2011, Achilleas Mantzios wrote: > another thing that puzzles me is power. > This board : http://www.ebay.co.uk/itm/USB-Eight-Channel-Relay-Board-RS232-Serial-Controlled-/110710333092?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item19c6d99ea4 > needs VDC 12V supply > while this one : http://www.ebay.co.uk/itm/USB-Four-4-Relay-Module-Board-Home-Automation-/180646300804?pt=LH_DefaultDomain_0&hash=item2a0f5bcc84 > is self powered from USB. > > batteries do not come cheap, and having an extra AC/DC adaptor is not very good either ... That 4-relay one might better suit your application then, if FreeBSD usb recognises it. It seems to use the same (FTDI?) drivers under windows as the other one, but I know almost nought about USB device detection. > another thing is the relay parameters, i see various figures : > Relay parameters: 5V / 72mA, 15A/24VDC (120VAC), 10A/250VAC or > Each switch 12VDC/15A or 240VAC/10A or > Open (No) and Closed (NC) Contacts rated for voltages: 12VDC/15A; 24VDC/15A; 125VAC/15A; 250VAC/10A > > my specific application i want to drive is this wireless xmitter : > http://www.visonic.com/Data/Uploads/MCT_100_Installer_Guide_English_DE2241U.pdf > Should i assume my device that i want my relay to control will have voltage of 3V? > > for which Voltage/Ampere figures should i opt? are those figures crucial? 5V / 72mA is the relay solenoid drive current. 4 of these switched on would use ~300mA, leaving 100mA for the other board circuitry. The 12V board's relays use the same drive power, 360mW, ie 12V @ 30mA. The relay switched contacts are rated at 12VDC to 15A (180W) or 240VAC to 10A (2.4kW!), whereas your MCT 100 is only watching for NC contacts to open; closed circuit current will be a few mA at most and you won't see more than 5V over the open contacts .. ie, not an issue. > thanx a lot A pleasure. cheers, Ian
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