### Vmax to Vrms conversion

Vmax of a sine wave voltage waveform is defined as the Positive Amplitudes on the sine wave.

The Vrms is defined as square root of the mean of the squares of the values for the one time period of the sine wave.

Following is the formula for Vmax to Vrms conversion.

V

_{rms}= 0.707 * V

_{max}

Where V

_{pp}is the max voltage and V

_{rms}is the root mean square voltage. To Calculate V

_{rms}from V

_{max}enter the value in V

_{max}and hit V

_{rms}button.

To Calculate V

_{max}from V

_{rms}enter the value in V

_{rms}and hit V

_{max}button.

**Need Help? Please leave a comment, I'll get back soon with a reply!**

Hello sir, Hope everything is well at your side. I read most of your posts and I really appreciate for your hard work and prompt replies. Actually this is my first comment on your web site, coz I really need your help regarding one unlabelled high amps transformer I got from one old microtek 2KV ups. The transformer is working fine, the primary has 4 inputs, and the secondary output volts depends upon the the selected inputs. The total AC RMS output am receiving is approx 12v, 15v, 18v respectively. But when I try to convert ac to dc with bridge rectifier 1N4007 and 1200uf 50V caps am getting approx output of 16v, 21v, 25v. And the bridge and filter is getting busted if the polarity (+ & -) gets short circuited by mistake. I tried a lot and unable to drop stable voltage to 12v and so. I googled a lot but couldn't find any solution. I tried using LM7812 voltage regulator but when I used with a 6amps peltier module (TEC1-12706) the LM7812 is getting extremely very hot within 2 second and may burn any time.

ReplyDeletePlease help me out. First of all I wanted to know how to calculate the total ampere does the transformer supports (The dead inverter rating is 2KV) plus any solution from your side to drop the DC voltage 16v to 12v and so on? Please do the needful. Waiting for your kind reply.Thanks in advance.

Thank you very much Shaan,

DeleteYou can never expect a stable or fixed voltage from a transformer rectified DC, you will have to employ a voltage regulator circuit for achieving a constant output.

the 1N4007 is getting burnt because the trafo current could be very high, and shorting the output will definitely bust the tiny 1N4007 diodes instantly, in fact even the bigger diodes...shorting must never be done.

you can try an LM338 based voltage regulator design, which will allow you to get a variable output from 1.25V to maximum of supply input limit...and this IC is short circuit protected internally which means that the IC will be always safe.

but make sure that the diodes are rated at 5 amps...meaning you might have to use 6A4 diodes for the bridge, and not 1N4007

for knowing the current you might require a current clamp meter

DeleteAm glad that you replied so soon.. Thank you very much.. Will surely try as you said. And also i tried yours zvs induction design and it really worked well without any issue.. Keep up for all your good stuffs you developed and shared online..

ReplyDeleteThanks & Regards,

Shaan

you are welcome Shaan...appreciate your efforts very much!

Delete