1
\$\begingroup\$

I have a full wave center tapped transformer circuit with input voltage of 220V How do I get an output voltage of 15V. What equations should I use ?

Here is the circuit:

enter image description here

\$\endgroup\$
  • 1
    \$\begingroup\$ What is a centre tapped rectifier? \$\endgroup\$ – Andy aka May 16 at 21:27
  • \$\begingroup\$ Updated the question \$\endgroup\$ – ahmed osama May 16 at 21:31
  • \$\begingroup\$ It's the transformer that's centre-tapped. You need to fix the title and the question. \$\endgroup\$ – Transistor May 16 at 21:32
  • \$\begingroup\$ Sorry about that, I am still a beginner \$\endgroup\$ – ahmed osama May 16 at 21:34
  • \$\begingroup\$ You must reply. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 17 at 0:57
0
\$\begingroup\$

enter image description here

Figure 1. Centre-tapped transformer with full-wave rectification.

Because there is no smoothing capacitor you just need a 15-0-15 V transformer. (You will lose about 0.7 V because of the diode drops so your actual output voltage will be 14.3 V DC.)

If you want smoothing you will be adding capacitors which will increase the average DC output voltage. There are many, many articles explaining this on the web.

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 2. A more usual way of drawing the same circuit with the power-supply on the left and the load on the right.


From the comments:

I want to understand it and what about the value of resistance between the two diodes.

It should be clearer in Figure 2 that the resistor is the load (whatever is being powered by the power-supply). It could, for example, be a light bulb or a motor.

One thing to watch is that the transformer will have a maximum power rating, usually in VA (volt-amps). In a real circuit you need to make sure that the current drawn by the load (R) is not greater than the transformer can supply without overheating.

See Electronics Tutorials for a good introduction.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ I am a newbie into this. I want to understand it and what about the value of resistance between the two diodes. I need to do a circuit simulation using a program like proteus \$\endgroup\$ – ahmed osama May 16 at 21:58
  • \$\begingroup\$ See the update. \$\endgroup\$ – Transistor May 16 at 22:05
  • \$\begingroup\$ Using Max VA rating compute V/I and raise the R by 30% as the minimum R derated for power factor when you add a Cap. The RC =T must be about 80 ms = 8/2f for ~10% ripple is a rough estimate \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 16 at 22:06
  • 3
    \$\begingroup\$ @Tony, that's likely to be as much use to the OP as a chocolate teapot. \$\endgroup\$ – Transistor May 16 at 22:08
  • 1
    \$\begingroup\$ There is no requirement in the question for a smoothed DC output. Give the guy/gal a chance to figure out how a rectifier driving a resistor works first. \$\endgroup\$ – Transistor May 16 at 22:17
0
\$\begingroup\$

How about you do your KVL homework on sinewaves, source voltage, turns ratio and peak to full-wave conversion charts to proof and I'll show you the answer.

I used 240Vrms 50Hz because I assumed you were not in Canada. Correct me if I was wrong.

My diodes conducted 0.73Vpk into 100 Ohms. But you can assume 0.7V

enter image description here

My simulation using arbitrary load R of 100 Ohms and Vrms is computed on plots with Vmax and Vmin shown.

| improve this answer | |
\$\endgroup\$
  • \$\begingroup\$ I don't really understand what you mean, Like I said I am a total beginner to this \$\endgroup\$ – ahmed osama May 17 at 1:59
  • \$\begingroup\$ You must understand how it works before the math \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 17 at 2:00
  • \$\begingroup\$ Well, I know that it unifies the direction of the current by using the diode as a switch that only lets current flow in one direction \$\endgroup\$ – ahmed osama May 17 at 2:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.