Using a 12 V DC wall wart. Do I need an extra 12 V regulator circuit?

Thread Starter

hrstar24

Joined Apr 7, 2009
32
Basically I need to take the wall voltage and provide 3.3 V, 12V, and 30 V DC voltages to power various components in my project. I decided to use a 12 V DC wall wart to convert the wall AC to DC.

I already got the 3.3 V and 30 V done using a boost converter and a regulator, but now I am stuck on the 12 v.

I measured the wall wart open circuit, and it is ~12.3 V. I am using the 12 V to provide voltage rails for an op amp, as well as bias a photodiode. My question is do I need to use a circuit to regulate this 12 v from the wall wart, or is a wall wart stable enough? Is there a simple transistor or Zener diode circuit that can be used to provide some power surge protection or something? So far I haven't been able to find any 12 v in 12 v out voltage regulators
 

bertus

Joined Apr 5, 2008
20,049
Hello,

The mentioned wallwart is regulated.
From the given link:

Description: This is a high quality AC to DC 'wall wart' which produces a regulatedoutput of 12VDC at up to 600mA. These are switch mode power supplies which means the output is regulated to 12V (no more 14V outputs!), and the capable output current is much higher (600mA!).
There will be no need for further stabilisation.
A couple of decoupling capacitors will be needed.
Decoupling or Bypass Capacitors, Why?

Bertus
 

Thread Starter

hrstar24

Joined Apr 7, 2009
32
Oh wow should have read that lol sorry. So that answers a big part of my question, but I don't have much experience working with diodes in filters... is there an example of a filter circuit that would work that he is talking about?
 

bertus

Joined Apr 5, 2008
20,049
Hello,

Can you post a schematic of the opamp / photodiode circuit?
That way we can see where to add extra decoupling if needed, as switching powersupplies can make some noise.

Bertus
 

iONic

Joined Nov 16, 2007
1,650
It would be nice to know what you plan to operate with the adapter. Will you be using 3.3V, 12V, and 30V all at once?
 

SgtWookie

Joined Jul 17, 2007
22,201
I suggest that you don't exceed 500mA with this supply, which is ~80% of its' rating.

While the SparkFun blurb claims "high quality", the comment entered on October 13 states 3 of 12 they purchased have failed, and the quality of assembly was poor.
 
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