Canon no longer makes CanoScan 8800F AC adapters, help needed to replicate its functionality
Sounds like a job for "time delay relay"/"delay-on relay". You have three options:


Buy industrial 24V units. They are beautify and expensive. Example:
http://www.alliedelec.com/schneider-electric-magnecraft-822td10h-uni/70185255/ ($57)
Buy cheap relays from ebay:


http://www.ebay.com/itm/New-DC-12V-Delay-Adjustable-Timer-Relay-Switch-Module-0-to-10-Second-/261852010468 -- this one is $1 with free shipping, but it is 12V only so it will also 12v power source.
http://www.ebay.com/itm/DC-24V-1-Channel-Relay-Module-switch-on-delay-turn-on-up-to-1-hour-relay-24V/221522754320 -- this one is $8 and I think it does what you need if it will survive 32 volt (you never know what the real max voltage of '24V' circuit is)

Assemble one. Most 555 circuits cannot operate off 32V DC, so use transitor based circuit such as this one:
http://www.bowdenshobbycircuits.info/page2.htm#delay.gif
This one has great property that three transistors would limit the voltage on capacitor, so there is no need for high voltage capacitor. You will want to increase 10K resistor to 20-40K and use a relay which can handle 32 volts (or add an extra resistor to 12 V relay)