Hi, so im trying to use this transformer as powersupply and it already has a rectifier and capacitor to filter the output, my concerns are the following :
-Votlage output from the rectifier is 20v but it charges the capacitor upto 27v
-also scared to use it on my amplifier cuase the current isn't regulated

Im just a newbie so I'm trying to gather more information for my project

 

Welcome to AAC.

Voltage output from the rectifier is 20v but it charges the capacitor up to 27v

Are you sure the 20V is from the rectifier and not the transformer? Something could be wrong if 20V on the rectifier gives 27V on the capacitor.
If the transformer has a 20V rating, this is RMS (root mean square), so the peak voltage for a sine wave will be 20 x the square root of 2, = 20 x 1.414 = 28.3V. If the rectifier is a bridge, there will be a voltage drop across two diodes, so the capacitor will charge to 28.3V - 2 x 0.65V = 27V.

also scared to use it on my amplifier cuase the current isn't regulated

Is your amplifier rated to handle a 27V supply? If so, it will draw whatever current it needs.

 

Regular transformers with rectifiers and capacitors will charge the output up to 1.4 times the nominal AC value in Volts RMS. So if your AC rms voltage is 10 volts it will charge up to 14 volts DC and if AC rms is 20 volts then it will charge up to 28 volts DC, and that is before you apply a load.

To get 20v output constant you need a voltage regulator on the output.

 

Welcome to AAC!

-Votlage output from the rectifier is 20v but it charges the capacitor upto 27v

The peak output voltage at the filter cap will be 20V * 1.414 minus the voltage drop for whatever rectifier you're using; 1 diode drop for half wave, 2 for a bridge rectifier. The output voltage will be higher if the transformer isn't loaded.

-also scared to use it on my amplifier cuase the current isn't regulated

The amplifier will only take what it needs after you regulate the voltage to what it needs. What is the amp's current requirement and what is the transformer secondary rated for?

 

scared to use it on my amplifier cuase the current isn't regulated

It should be okay if the amp's rated voltage is above 27V.

Depending upon the required maximum current, you could use a regulator such as the common LM317, to give a steady DC out.

 

Welcome to AAC.

Are you sure the 20V is from the rectifier and not the transformer? Something could be wrong if 20V on the rectifier gives 27V on the capacitor.
If the transformer has a 20V rating, this is RMS (root mean square), so the peak voltage for a sine wave will be 20 x the square root of 2, = 20 x 1.414 = 28.3V. If the rectifier is a bridge, there will be a voltage drop across two diodes, so the capacitor will charge to 28.3V - 2 x 0.65V = 27V.

Is your amplifier rated to handle a 27V supply? If so, it will draw whatever current it needs.

It's only py rated to handle 24v 5a so im also trying to find a way to regulate the voltage

 

Hi, so im trying to use this transformer as powersupply and it already has a rectifier and capacitor to filter the output, my concerns are the following :
-Votlage output from the rectifier is 20v but it charges the capacitor upto 27v
-also scared to use it on my amplifier cuase the current isn't regulated

Im just a newbie so I'm trying to gather more information for my project

 

Feed the output of the transformer into four 1N4001 diodes in series or use an LM7824 voltage regulator.

 

Welcome to AAC.

Are you sure the 20V is from the rectifier and not the transformer? Something could be wrong if 20V on the rectifier gives 27V on the capacitor.
If the transformer has a 20V rating, this is RMS (root mean square), so the peak voltage for a sine wave will be 20 x the square root of 2, = 20 x 1.414 = 28.3V. If the rectifier is a bridge, there will be a voltage drop across two diodes, so the capacitor will charge to 28.3V - 2 x 0.65V = 27V.

Is your amplifier rated to handle a 27V supply? If so, it will draw whatever current it needs.

It is only rated for 12-24v 5a but i wanna regulate the transformer output voltage to 20v

 

It should be okay if the amp's rated voltage is above 27V.

Depending upon the required maximum current, you could use a regulator such as the common LM317, to give a steady DC out.

Might try this one. Thanks

 

Welcome to AAC!
The peak output voltage at the filter cap will be 20V * 1.414 minus the voltage drop for whatever rectifier you're using; 1 diode drop for half wave, 2 for a bridge rectifier. The output voltage will be higher if the transformer isn't loaded.
The amplifier will only take what it needs after you regulate the voltage to what it needs. What is the amp's current requirement and what is the transformer secondary rated for?

It is only rated for 12-24v 5a but i wanna regulate the transformer output voltage to 20v replied on my thread with some pics for the transformer specs

 

Is the transformer rated to deliver the 5 A that your amplifier might need?

If you want to regulate it with a 78xx regulator IC, then you are going to need to include circuitry to provide current bypassing since those regulators don't like to put out more than 1 A of current (if properly heat-sinked).

 

Is the transformer rated to deliver the 5 A that your amplifier might need?

If you want to regulate it with a 78xx regulator IC, then you are going to need to include circuitry to provide current bypassing since those regulators don't like to put out more than 1 A of current (if properly heat-sinked).

I don't really have way to find what mu transformer current rating is

 

I don't really have way to find what mu transformer current rating is

What are the transformer core dimensions? If the marking CZ66X36 indicates dimensions of 66mm x 36mm then the transformer is unlikely to be rated above ~1A output current.

 

It is only rated for 12-24v 5a but i wanna regulate the transformer output voltage to 20v replied on my thread with some pics for the transformer specs

Do you need 20v at 5 amps? That is significant power you may have to use a switching regulator. A linear regulator may eat up too much power and get hot.
You also need significant capacitor filtering to keep the unregulated voltage dips above about 22 volts.