Steve,

I have seen hobby projects using triacs coupled with linear drives like 555 timer IC without any opto.

It could trigger both -ive as well as +ive firing.

When MT1 of the triac tied to +ive of the circuit's PSU it triggered on -ive output and when MT1 tied to -ive of the PSU it triggered on +ive output.

I am also interested on using triac with 2051 and without opto, to reduce the cost of my project.

Let's try.

BL/