On 9/28/11 6:13 AM, TexasRF@aol.com wrote:
> Hearing and seeing a relay close is reassuring. That aspect is lost with
> solid state switches.
> A relay is very tolerant of voltage levels, current, and polarity. A
> bulletproof device if there ever was such a thing.
> Use of three relays allows close duplication of the original control
> circuit. One for +, one for -, one for both and none for the default
> state. Only one relay at a time needs to be operated making the control
> logic quite straight forward.
The control box doesn't have any relays, just a rotary switch.
The box at the antenna does have relays, but I don't think anyone is
contemplating changing that. There are also multiple versions of the
RCS-4, for what it's worth (one has 3 relays in the remote box, the
other has 2).. but the control scheme is the same. half wave rectified
AC as one bit of control, the other polarity as the other.
There is an advantage of using a pair of small SPST relays as the
interface between computer and remote box, and that has to do with
providing galvanic isolation. One less place for a ground loop, etc.
there are some small, cheap solid state relays that would work, too (or
optoisolated SCRs)
You'd have to decode the diode indicators some other way, of course.
> KISS works for me!
> 73,
> Gerald K5GW
> In a message dated 9/28/2011 7:47:12 A.M. Central Daylight Time,
> jimlux@earthlink.net writes:
>
>
>
> You only need 2 relays at most. (at least to actuate the remote relays)
>
> A pair of SCRs? (and some diodes) I haven't had my coffee yet, so I
> can't think of how you'd arrange to get them biased corectly.
>
> A triac, with the gate pulse timed right after the zero crossing.
>
> >
>
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