[GreenKeys] GreenKeys Digest, Vol 67, Issue 19

[John Nagle]

> Date: Sat, 22 Aug 2009 21:44:51 -0500
> From: "Herb Graeber" <hhg at suddenlink.net>
> Subject: [GreenKeys] ST-8000 Autostart
> 
> Before I break out the soldering iron, 2N2222 and a relay with
> 110VAC contacts I thought I would ask the group if someone
> has a simple circuit that they have designed for taking the
> Motor Control from pin 12 of the terminal data connector and
> using it for autostart.  I'm sure this has been done many times
> already and there is no sense in me reinventing the wheel.
> Please let me know if you have done this or if you have any
> ideas.  Thanks...Herb K5HG

I use a Continental SVDA-3V25 solid state relay for Teletype
motor control.  Input is 4 to 32V DC, so it can be run directly from
TTL or RS-232 levels, and it will switch 20A at 24 to 330 VAC.
These are solid-state bricks with screw terminals, a
clear protective cover, and a built-in LED to show when they're
on.  They're a widely used industrial control part.  Note
that these bricks must be attached to a metal chassis or plate for
heat-sinking, provided with their own heat sink, or derated.

http://www.ciicontrols.com/products/sv.htm

The 10 amp model is on eBay at the moment, with an grossly inflated
shipping cost.

http://cgi.ebay.com/Continental-Solid-state-relay-SSR-SSDA-330-10-NEW-omron_W0QQitemZ120403796702QQcmdZViewItem

Mouser charges $24.75 for the 20A part, $18.00 for the 10A part.

Omron has some comparable parts.

I've used these things for Teletypes and in industrial applications, and
they're a good way to get from low-level signals to serious power control.

				John Nagle