Is there a "safe" way to achieve continuity activation on older (2010) iMac and use a Bluetooth 4.0 dongle?

Thank you for your response. As I understand it, the older Bluetooth chip in the iMac is the source of my problem, which - as you have correctly stated - is a definitely a hardware issue. But could this shortcoming could be overcome with the addition of a USB Bluetooth dongle? The article I referred to in my original post can be found here (with other links contained therein):

http://www.macworld.co.uk/how-to/mac-software/get-continuity-handoff-airdrop-on- old-mac-3582632/

This suggests a minor patch will enable Continuity on an older mac (like mine) by using the dongle to handle Bluetooth 4.0 communications with iOS devices. I know nothing about OS X, and would be very reluctant to execute this hack for fear I might do more harm (inadvertently) than good. I have not been able to find anything in the Apple tech literature to suggest that they are aware of this problem, or that they intend to do anything about it. Since AirDrop works fine between my various Macs (via wifi), I am still at a loss why my iOS devices won't default to a wifi connection with my iMac when a Bluetooth connection cannot be made due to chip incompatibility.

If the suggestions in the MacWorld UK article are correct, I am at a loss as to why Apple hasn't addressed this compatibility issue and provided a "fix" in one of the El Capitan updates. Maybe there is a marketing angle to this, with Apple preferring to incentivise the replacement of my otherwise serviceable and reliable mid-2010 iMac with a newer model?

I have also discovered a purely hardware solution that looks more attractive.

http://www.theapplelounge.com/feature/exclusive-how-to-enable-handoff-on-older-m acs-running-os-x-yosemite/

This involves replacing the Airport Extreme and Bluetooth A1115 cards, then inserting the following aftermarket parts available from OSX WIFI:

Apple Broadcom Bcm94360cd - 802.11 A/B/G/N/AC + Bluetooth
4.0 With Adapter For iMac 2009, iMac 2010 and iMac 2011

http://www.osxwifi.com/adapters/apple-broadcom-bcm94360cd-802-11-a-b-g-n-ac-blue tooth-4-0-with-adapter-for-imac-2009-imac-2010-and-imac-2011

It seems like this approach addresses the hardware problem directly, and at the price shown, would be a reasonable way to go. Review comments posted on the OSX WIFI web site are quite encouraging.

I would be very interested to learn whether anyone viewing this thread has experience with this device, or have other suggestions.There are probablyu a lot of us out there with older iMacs that could surely benefit from this modest upgrade.

Thanks.

One more thing - I am satisfied that the USB Bluetooth dongle approach will not work.