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Old 1st June 2021, 06:37 PM
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Quote:
Originally Posted by chrisb View Post
Thanks all for your responses. Another question regarding set-up, I currently use a sonoff basic R3 and the FADU timer app to control my krokus which works off the 240v, is there any issue with having the sonoff on the 240v side of the transformer? There's often a lag when you cut the power to a transformer but is this minimal because the power needed by the lamp?
That is the only way you can use a Sonoff R3 - it can only switch mains voltages as it gets its own power from the mains input and switches the live side using its relay.

There is a lag when switching the enlarger lamp off, but there is also a corresponding lag when you switch it on. In practice, these are unlikely to result in the same amount of light hitting the paper in each case so if you are making test strips using multiple exposures then you should make your final print using the same sequence of exposures (this is the same with most timers unless it has a sensor to monitor how much light has reached the paper during the exposure, or if the enlarger has a shutter). There is another potential issue with using a regulated power supply in that the circuitry can introduce other delays as capacitors charge and discharge etc.

For example, if you determine that your best test strip is the 4th strip along which adds up to a total of 16 seconds then you should not use a single 16s exposure for your final print - use the same 4 exposures as for the test strip. Saying that, depending on several variables, it may be close enough for practical purposes, you would need to try it and see. The FADU timer has an offset setting that lets you adjust the timing to allow for this disparity in on/off exposure, but it is a bit awkward to determine how many milliseconds to add or subtract as it is a trial-and-error process. The method is explained in the manual.

An alternative option is to use the SINGLE mode for test strips so each strip gets its own single exposure instead of a cumulative one, but that obviously takes longer.


Cheers, Bob.

P.S. If you are using the "PULSE R3" Lamp Controller mode with the AUTO strips method, try setting a 2 second Delay between strips as the Sonoff can be VERY slow to respond in this mode causing things to get out of sequence and messing with the timing. If your network is fast enough I would suggest using "BASIC R3" mode instead. Ideally, reprogam the Sonoff with the FADU firmware!

Last edited by Bob; 1st June 2021 at 07:08 PM.
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