upgrading mechanical locks by simply removing existing mechanical pop out cylinders and replacing the same with an improved electronic pop out cylinder according to the present invention thus the embodiments illustrated in fig1 20 have substantial benefits and can be used in a variety of applications such as with a variety of vending machines bottle machines atm machines etc in another alternative construction the driver 2310 can be used to move the locking bolt to the extended position rather than or in addition to using a spring 2430 in this regard the cut out section 2410 can be a narrower channel such that the driver 2310 moves the locking bolt in the directions a and b fig2 a although the preferred embodiments do not use common tumbler pins and keys having bitting surfaces the key slot 2520 into the plug 2500 can be made to have a specific configuration that allows the insertion of only a particularly shaped key the plug 2500 could also be modified to include multiple parts where a certain part thereof is connected to the solenoid such that a key means must rotate that certain part of the plug further the plug 2500 could be modified to contain common tumbler pins operated by keys having bitting surfaces in the environment where the cylinder 2000 is small e g such as with a standard n a m a lock cylinder the plug is very small and is preferably made without locking pins and or separately moved parts the invention being thus described it will be apparent to those skilled in the art that the same may be varied in many ways.