AC to DC Power conversion

Thread Starter


Joined Aug 24, 2014
I am new to Electronic, i would like to know AC to DC conversion without transformer is safer or with transformer?

Using the Converting AC to DC using Capacitor as below listed table
Capacitor CodeCapacitor valueVoltageCurrent
104k0.1 uF4 v8 mA
334k0.33 uF10 v22 mA
474k0.47 uF12 v25 mA
684k0.68 uF18 v100 mA
105k1 uF24 v40 mA
225k2.2 uF24 v100 mA


Joined Feb 25, 2011
degrees of safe .

Used safely , both with and without a transformer is "safe", !!

You show an ambiguous table,
a circuit diagram of what your thinking would be needed to help us determine your question


Joined Aug 21, 2008
If you are new to electronics then a power supply without a transformer for isolation from the mains would pose a grave danger to you. Most likely you will only experience painful shocks occasionally but there is always a chance of a lethal shock or damage (such as burns and cuts from reactions to being shocked).

I try to use wall warts or other already made power supplies deisnged and certifieid to be safe as often as possible. The hard part is already done and is ready to use, leaving more time on the special parts of projects.

Thread Starter


Joined Aug 24, 2014
Dear Andrewmm, thank you for immediate response.

I have created Water pump using Solenoid valve, as part of the Circuit there will be 2 power inputs

1 is for Circuit
2 is for Solenoid Valve

To avoid 2 transformer, it would be better to use Capacitor based. Kindly advice.


Joined Aug 21, 2008
How big would the capacitor have to be in order to supply on the average 3 amps?

Does your microcontroller connect to anything outside of the solenoid circuits?


Joined Sep 17, 2013
Just dropping the voltage with a capacitor is unsafe and not practical for those currents. You must use a transformer, be it one designed for 50/60Hz or one inside a high-frequency switch-mode power supply. The transformer provides isolation from the mains for safety.


Joined Nov 29, 2009
Whilst agreeing with the previous warnings, I would add that designing a water pump using a solenoid and proposing to use capacitive voltage level changing to run it sounds like a disaster waiting to happen!