Pros or Cons thoughts needed

Thread Starter


Joined Jul 26, 2013
110/120vAC mains sent through a full bridge rectifier, filtered and a zener off-loading for anything over 120vDC. In theory or in practice, what would be the worst-case scenario relating to risks (both component and/or injury) assuming the unit was fully sealed save for ventilation? I've been working on different approaches to a project (low-current) and thus far this seems to be the most efficient direction to take in regards to energy waste (heat, hysteresis, etc.) but I'm fishing for input from others if there's anything I'm overlooking. Thanks!


Joined Sep 30, 2009
May be wrong here but, with out an isolation transformer this is not a good idea. Isolation from the mains is always a requirement, especially for discussion on this site and safety.


Joined May 3, 2013
1) You will get this Topic killed " . . . .as per Terms of Service .... Transformerless ....etc etc.
2)The DC output will be Floating - so earthing not possible - electrocution hazard.
3) The Zener needs to be designed to Sink all the expected load current - Highly Sophisticated Heater
4) A switching Regulator avoids all the above and will be recommended.



Joined Oct 2, 2009
If one is working on a design for a power supply, from AC mains to constant voltage DC output, the first requirement is to specify the output voltage and the maximum current required.


Joined Sep 9, 2010
...and a zener off-loading for anything over 120vDC.
This will cause an enormous current to flow until your bridge overheats and/or you blow a circuit breaker.

Since you didn't already know that AND this is a mains-direct topic, this thread will be closed soon for your own good.