All of what I wrote in my last post is I believe correct... for a device that needs 200 - 300 mA Max current from a 24VA transformer and yes you do need a 24VA transformer to supply 24 VAC @ 1A load current. A "Half Wave Rectifier will give you 1/2 (approx) of the 24V ac or about 12 Vdc. I suggested a large enough diode that the surge resistor might not be needed and that there would be 9 to 10 Vdc available for the regulator.
The best method (IMO) is a switcher and I had very good results with the part i mention next... I made about 100 of them (Not me I just did the design and PCB layout) but they were really quiet and trouble free.
I built a lot of 24Vac based switchers in 2003 - 2006 I used an LT1170 because I needed about 3A for 10 - 15 seconds to power a 10W transmitter. It was an easy device to use... all the information you will need is in the data sheet. There are three varieties of this device, LT1170 - 1 - 2 for 5A @60 V max input voltage (LT1170 2.5 A (LT1171 and 1.25 A for the LT1172 I used the 5 lead TO-220 and the 5 Lead SMT package and all worked very well. This is the link to the data sheet.http://www.stanford.edu/class/ee122/Parts_Info/datasheets/LT1170.pdf
an ac transformer and a bridge rectifier work very well with this device for a stable and adjustable buck mode power supply. If you need a lot of current. If you are just doing a small control device then my last post should have more than enough information. I would add that a Tranzorb should be included for transient protection on the secondary of the transformer to protect the diodes. I also included poly fuses to prevent fires in case of component malfunction. I also used tranzorbs on the rectifier output as these were used in Kansas on a Rural Power Grid where KV level spikes were common and some of long duration... 1/2 second spikes were measured... Usually though when the Power company did a "Load Drop", A frequent nightly occurrence as most of the big Agricultural companies used power at night when rates per KW were cheaper.