With the 24 V dc, we know what you mean: average voltage of 24 V. The 24 V ac is a little less clear. Probably you mean írmsí (root-mean-square), which is the most common way of specifying ac voltages.
Anyway, the answer is no.
If the rectifying circuit has some capacitance at the output side (as they generally do) and if itís not hooked up to some load that drains the capacitors, the voltage will approach the peak voltage, which is 20.5
*24V, or about 34 V. Small internal leakgae will probably keep it from getting quite that big.
If you hook a big load (small resistance) to the output, and if your ac voltage source can easily handle the load, the voltage will vary over time but the average will just be the average absolute value of the input ac voltage, or (2/pi)*24V, about 15 V.
When you use a wall-transformer dc power supply for some small electronic device, it has load-dependent ouput voltages like this. So if you use one that is rated for the right voltage but the wrong current (which depends on load), you may actually get too high or too low a voltage.
(published on 09/15/06)