Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

The difference between designing DC and AC power supplies

Status
Not open for further replies.
L

lyzrdstomp

Junior Member level 2
Joined
Apr 13, 2007
Messages
20
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Midwest US
Activity points
1,448
Okay, this IS the elementary electronics board, so bare with me...

I just finished 2 variable 1.2-30V/2A regulated DC power supplies (one made with perf board and wire, the other with etched board), and it was much easier (and fun!) than I thought (of course, having a schematic drawn by someone else helped :)

Now I want to build a comparable (30Volt) variable AC power supply.

Knowing that the Bridge Rectifier is behind converting AC to DC in a DC supply, is it as simple as not using the Bridge Rectifier to get AC, or is it more involved than that?

If it is that simple, can I just put in a switch to "bypass" the rectifier when I need AC so I can put both in the same case?
 

power supply with lm350 have noise

Probably you have used a LM317 or LM350 to build your DC variable power supply. But it will not work if you want to do the same for AC variable power supply, simply taking the rectifier off the circuit.
As a suggestion, I would use a VARIAC (variable transformer) with work with a rotationary cursor over the winding, so varying the output voltage directly over the winding. Remember the output is not isolated from the power mains network, so you could use also an isolation transformer.
Another way is to use thyristors devices (like TRIACs) to vary the rms voltage by varying the conduction angle (this causes a lot of noise and distortion, but it is used a lot).
 

Re: AC Power Supply

rkodaira said:
Probably you have used a LM317 or LM350 to build your DC variable power supply. But it will not work if you want to do the same for AC variable power supply, simply taking the rectifier off the circuit.
As a suggestion, I would use a VARIAC (variable transformer) with work with a rotationary cursor over the winding, so varying the output voltage directly over the winding. Remember the output is not isolated from the power mains network, so you could use also an isolation transformer.
Another way is to use thyristors devices (like TRIACs) to vary the rms voltage by varying the conduction angle (this causes a lot of noise and distortion, but it is used a lot).
Click to expand...

Thanks for the info. I didn't think it would be that simple. :)
I guess I was hoping to find an AC power supply circuit to build (if one exists)–I'm in the "new to electronics and can't wait to build my next project" phase.

Take care.
 

Re: AC Power Supply

can i have your example circuit for the variable dc circuit??
i just want to see as reference.. me also also having the same problem with u..XD
 

AC Power Supply

When you bypass the rectifier to get AC supply, you should also disconnect the circuitry which comes after the rectifier (Filter capacitors, regulator IC's etc). But still then varying the AC 30 volts is some what troublesome.Good luck
 

Re: AC Power Supply

For an AC variable power supply you need a very complex circuitry. ("really very").
The problem is to obtein good 60 hz wave .
Too dificult, you need very experienced people help or use a VARIAC transformer, I think the easiest way.
 

AC Power Supply

what about making switching variable AC. as an example, maybe we can set 3 , 6 and 9 Vac. then we use switch to change between the ac value... can it be done?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top