Does a vivitar 530fd flash work with a under 12v remote flash trigger?
This is the data from the Strobe Trigger voltage page linked by the previous poster for the 2 model numbers closest to yours; 530FC 8.3V, according to Bob Thibodeau 550FD 8V, according to Ted Felix — only 4.24V, per Stephen Sugiyama, and 5V per Timothy Horn (serial 0031524) — but 6.66V from Rick Zotz, 7.5V from Tri Do, and 10.18V (serial 5031715) by John D. Duvall Vivitars are a bit notorious for having trigger voltages all over the place but the above tested results seem to indicate its below 12V. The only way to be really sure is to test it with a multimeter if you have one or can borrow one. The instructions are linked on the Trigger Voltage page.