Date: Mon, 22 Feb 1999 19:11:47 -0600 From: David Kelly <dkelly@hiwaay.net> To: Leif Neland <leifn@neland.dk> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: How to control a relay for the printer Message-ID: <199902230111.TAA30344@nospam.hiwaay.net> In-Reply-To: Message from Leif Neland <leifn@neland.dk> of "Mon, 22 Feb 1999 22:47:18 %2B0100." <Pine.BSF.4.05.9902222223030.636-100000@arnold.neland.dk>
next in thread | previous in thread | raw e-mail | index | archive | help
Leif Neland writes: > I have spare com-ports, could I use some modemcontrol-bits to control the > relay? That is one way. It matters as to what the coil voltage and current your relay requires. Not likely you will be able to activate the relay with the very small current available on the serial port. You'll have to build an amplifier or such. Or a very small relay (check the DigiKey catalog for specs, experiment with an amp meter on your serial ports). With a small enough relay one could switch power from a power supply that could power the power relay for your printer. Am thinking RS-232 is only good for 10mA, which isn't enough to switch any relay that would be of much use. You'll need to use a transistor to drive the big relay. And you'll need a power supply ciricut to power that transistor and relay. Think a cleaner and quicker solution would be to buy an X-10 Appliance Module to plug the printer in, and a cheap controller ($15). When you want to print, push the ON button (several times to make sure it works) for the Housecode and Unit of your printer. Modern printers power themselves down when not used for a while. -- David Kelly N4HHE, dkelly@nospam.hiwaay.net ===================================================================== The human mind ordinarily operates at only ten percent of its capacity -- the rest is overhead for the operating system. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199902230111.TAA30344>