I have finished this 60 watt amplifier. It needs 50 V and - 50 V to operate. I created a power supply that has 50 V and -50 V using zeners. Refer to pic. Seperately, they are working as they should. But when i connect them, i don't know anymore. Please help!!! How can I solve this??? Any help would be much appreciated. 1st pic = Working 60 watt amplifier to 8 ohm load. 2nd pic = working DC supply with 50 V and - 50V. 3rd pic = connected together and BOOM! it's broken.

 

I'm having trouble understanding the schematic.
Do you really have 2,500 ohms in series with your Power supply output?
That protects the zener diode, but how will the amp get any power from the supply?

Use ohms law and calculate how many MILLI amps can be drawn from a 2.5kohm resistor with 50 volts source

 

Some rough numbers here: 60W from a 100V supply (about 50% efficiency) implies about 1A needed from the supply.
Your supply has 2 x 2.5k resistors in series. Maximum current 50V / 2.5k = 20mA. Your supply can't provide anywhere near enough current for the amplifier.

 

That PSU cannot run an Amp.
You need to to power the amp right from the PSU capacitors.
You need proper transformer secondary rating to get ±50VDC
You need a Tx of 36 - 0 - 36 VAC Secondary voltage with appropriate current rating.

 

I forgot wrong pic for the supply. I got the 2.5k value using a voltage divider. I also have 5 k ohm resistor in parallel with the zener. i got the values so that the voltage across the 5k resistor is about 51 V or so then its parallel with the zener.

 

Notice the supply has only wire between output and the rest of the circuit.

 

That PSU cannot run an Amp.
You need to to power the amp right from the PSU capacitors.
You need proper transformer secondary rating to get ±50VDC
You need a Tx of 36 - 0 - 36 VAC Secondary voltage with appropriate current rating.

So, i should remove the zeners, inductors and resistors. Then the output would come directly from the capacitors? What would the current rating of the transformer be?

 

Your zener could be utilized by a comparator circuit that monitors the amp voltage rails. You could use it to cut the preamp gain to prevent voltage sag at high volumes. Otherwise what are you using it for?

 

Only you know what transformer you have.

 

What is your designed power limit for the amp?
The transformer should have a bare minimum of 10% more VA rating. Preferably 25% more.

 

Your zener could be utilized by a comparator circuit that monitors the amp voltage rails. You could use it to cut the preamp gain to prevent voltage sag at high volumes. Otherwise what are you using it for?

I thought it was needed, because from our dc supply project in the past we used zeners.

 

View attachment 128143

Notice the supply has only wire between output and the rest of the circuit.

are the capacitors in the image in microfarad?

 

You could use a zener regulator but you should have high current regulators like in series regulators.
But this method is for those who want very strict regulation. And normally you don't need it.

 

What is your designed power limit for the amp?
The transformer should have a bare minimum of 10% more VA rating. Preferably 25% more.

the limit is 60 watt for the amp. what do you mean by the transformer should have bare minimum 10% VA rating? i don't understand

 

are the capacitors in the image in microfarad?

10,000uf ..Yes.

 

Yes micro.
It appears to be one .01uF and 10,000 uF.
You could parallel two 4,700 if it is easier to get.

 

the limit is 60 watt for the amp. what do you mean by the transformer should have bare minimum 10% VA rating? i don't understand

It means the tx should be rated 10% more than the power you need.
Like if you need 60W, it should rated like 66W.
Typically for a 60W amp a transformer of around 120VA is suitable for stereo amplifier operation

 

Thanks for the help, i really appreciate it, i will try the approaches you mentioned, but for now i'll sleep. i'll update again once i do something new. thank you

 

For stereo operation you would need a Tx of 35-0-35 VAC @ 3 Amps
You can drive a stereo one at ±50VDC all day long

 

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