How do you trigger a triac?

[boylesg]

I have the following circuit with some minor variations:



AC voltage is 24V
Vg is 5V
R is 390 ohms
There is a solenoid valve in place of the lamp.
Triac is MAC97

But the circuit does not work regardless of whether I connect R to 5V DC or GND.
The triac won't turn on.

So how do you turn a triac on?

 

[schmitt trigger]

Please get the data sheet and find which is the guaranteed trigger current.
As is, you are supplying about 7 mA, and unless it is a sensible gate Triac, the trigger current may be 10 mA or higher.

Also, unless the Triac is specified for 4-quadrant operation (again look into the data sheet), the Triac will trigger better with minus 5 volts.

 

[FvM]

Should work with MAC97. Either the real circuit is different from schematic or the part is defective. Did you already check circuit voltages with a multimeter? What do you see?

 

[schmitt trigger]

Also;
make sure you have not swapped MT1 and MT2.....this is a common beginners mistake.