There are SSRs for DC control that typically use a power FET to control the
output and should work for you. Cost is often higher than a mechanical relay
and there is an output voltage drop of usually 1.5V (at rated curent) on the
output switch. Reliability is good and they are quiet.
Opto22 is one major maker of solid state relays.
http://www.opto22.com/site/pr_cat_sc...s=100610161053
The relays on this page have DC control inputs and control DC or AC power
(one type of relay for DC and another type for switching AC).

Oppie
(who will be vacationing in Ludlow,Vermont this summer, elev 1250')

"---MIKE---" wrote in message
...
I am familiar with using solid state relays to switch 110VAC using a low
DC voltage to activate. Can these also be used to switch 12VDC (to pick
a 12 volt mechanical relay)?


---MIKE---
In the White Mountains of New Hampshire
(44° 15' N - Elevation 1580')