This is essentially a revival of an old thread (from Nov 2016), but I am a newbie and am not able to make comments or ask further questions on it...
In a nutshell - the Canon Canoscan 8800f scanner has a unique external power supply unit which supplies 32V dc, plus has a second 32V dc line which has a 1.5k resistance across it for 3 seconds. These Canon power supplies are almost impossible to get, and somebody had the good idea of taking a particular HP printer power supply, which also gives 32V dc, and inserting a circuit on this second supply line which performs the function of giving it the 1.5k resistance initially, then removing it with a timer, as this scanner requires.
In this previous thread, as linked above, two users here kindly offered designs for this delay/resistor-bypass circuit. At first I tried the second one, because it was more simple, submitted by 'Whit3rd'. This circuit functions, but it kicks in too soon, almost instantly. The scanner only responds and switches on if the delay is 2-3 seconds.
Looking now at the first circuit design, offered by 'ThreePhaseEel', it has more components, and I am about to order the components I haven't got to make it but...
I've three questions:
A: With Whit3rd's version, which components can I experiment with to increase the delay of it's response? Any suggestions of configurations to alter this?
B: With ThreePhaseEel's version, again, which components would most impact the delay, so I could substitute parts to get the right result?
C: Again also with ThreePhaseEel's design: could somebody please clarify/confirm the choice of capacitor in the design: ThreePhaseEel writes that '...the timing capacitor should be a stable, low-leakage type such as a polyester film or a good grade of tantalum cap...' - yet the cap is listed as 100uF which seems large for a Tantalum and is near-impossible to get as a Polyester Film... Is this correct? I have electrolytic caps this size. And what voltage for this cap? 50V seeing as the circuit is 32V?
Thanks in advance for any responses. I am not trained in electronic engineering, more an intermediate-level tinkerer. I can easily make these circuits, as designed by other people, but I don't claim to understand them to the point that I can modify or redesign them.