Vivitar 283's and 285's had a factory variable power module, Vari Power, for these flash units. Cheap, at one time, and only marginally effective at controlling the flash power.
I found a site, actually two sites, that detailed the making of a better variable power module using linear taper pots.
I finished mine today. I built two but I accidentally trashed one of the pots with a drill bit. So I show the one that works.
Mine is a bit different than either of the two I saw online.
I used three 100K ohm pots, wired in series, that give a total of almost 300K ohms resistance which allows full power selection and can be dialed down to a very low power. I cannot effectively measure the output at lowest power. Well, I can using a meter I guess, but I have no meter to measure the stop increments. I just can tell by the light emitted that it will be well under what I would ever need to dial the flash down too.
I found a site, actually two sites, that detailed the making of a better variable power module using linear taper pots.
I finished mine today. I built two but I accidentally trashed one of the pots with a drill bit. So I show the one that works.
Mine is a bit different than either of the two I saw online.
I used three 100K ohm pots, wired in series, that give a total of almost 300K ohms resistance which allows full power selection and can be dialed down to a very low power. I cannot effectively measure the output at lowest power. Well, I can using a meter I guess, but I have no meter to measure the stop increments. I just can tell by the light emitted that it will be well under what I would ever need to dial the flash down too.
