Designing a triac based regulatable DC supply
There are a few things to be aware of with this approach.


It is not isolated. The output must be considered live.




*Figure 1. Phase-angle and output current into a linear load. Source: Dimmers for LEDs.


Voltage will increase as the dimmer trigger delay decreases from 180&deg; to 90&deg;.
Once you reach the 90&deg; the rectifier and smoothing capacitor will give peak voltage output of \$ 220 \sqrt 2 \$. Unless you have a large load to quickly discharge the capacitor you won't see much variation in voltage between 90&deg; and 0&deg; because the bridge rectifier will be reverse biased.
To limit the voltage to 160 V you will have to limit the minimum resistance on the pot.
Your most likely failure is of triac short-circuit. This will apply full mains voltage to the rectifier and will blow the capacitor if not adequately rated. Loss of the dimmer capacitor would also tend to switch the triac on early.


I'd be very careful.