Official C12 Clone - Build and Support Thread

[Rob Flinn]

And I have to connect this wires here..So, I am not shure whether pin 7 goes to B-? All other pins are clear..

All I know is I would be connecting the pin that is forward and makes connection first to the Earth/Screen/0v connection. It's a safety connection, why would you potentially want to be connecting B+ before the safety connection when you plug it in ?

 

[slapavi]

All I know is I would be connecting the pin that is forward and makes connection first to the Earth/Screen/0v connection. It's a safety connection, why would you potentially want to be connecting B+ before the safety connection when you plug it in ?

Yes I understand. At the moment I'm a few steps from plug it in. Currently I need to connect all wires...Like this..
But, since I have the new revision of pcb, there is no ground designation on the pcb and that is the reason I am connecting pin 7 to the right place on pcb..

 

[slapavi]

All I know is I would be connecting the pin that is forward and makes connection first to the Earth/Screen/0v connection. It's a safety connection, why would you potentially want to be connecting B+ before the safety connection when you plug it in ?

Yes I understand. At the moment I'm a few steps from plug it in. Currently I need to connect all wires...Like this..
But, since I have the new revision of pcb, there is no ground designation on the pcb and that is the reason I am connecting pin 7 to the right place on pcb

Yes I understand. At the moment I'm a few steps from plug it in. Currently I need to connect all wires...Like this..
But, since I have the new revision of pcb, there is no ground designation on the pcb and that is the reason I am connecting pin 7 to the right place on pcb..

I wanted to say, I am asking for help in order to connect the wires correctly..

 

[Rob Flinn]

Yes I understand. At the moment I'm a few steps from plug it in. Currently I need to connect all wires...Like this..
But, since I have the new revision of pcb, there is no ground designation on the pcb and that is the reason I am connecting pin 7 to the right place on pcb

I wanted to say, I am asking for help in order to connect the wires correctly..

B- is 0v which is likely connected to Ground/Earth. It should be connected to pin 1

 

[slapavi]

So, to make my question simple again; I would only ask if somebody can confirm that this diagram of connecting wires is correct..

 

[Matador]

Yes.

GND was changed to B-, to denote that the heater secondary and high voltage secondary are (now) completely isolated on the PCB, and only connect together if you expressly jumper it that way. This allows for the possibility of negative heaters, or even negative high voltage (although I'm not sure why anyone would do that).

 

[slapavi]

Yes.

GND was changed to B-, to denote that the heater secondary and high voltage secondary are (now) completely isolated on the PCB, and only connect together if you expressly jumper it that way. This allows for the possibility of negative heaters, or even negative high voltage (although I'm not sure why anyone would do that).

Thank you very much for the explanation!!!

 

[Bel.kevin01]

@Matador

Thanks for all yours and Chungers work!

I'm on my second C12 psu build. Started on V1.4 2015 board, and now working on the most recent revision. To my surprise, the apex 460 psu I got for my second build is also changed a bit from my original.

I really would like to change the power transformers from the stock versions. And build these circuits into some nice enclosures. I can't find any transformers the give me 200v and 9.5v secondaries. What changes do I need to make to utilize one that has 200v and 12v instead? Am I able to trim the voltage down? Or do I need to substitute some components to accommodate that voltage increase?

Thanks again!

 

[Matador]

What changes do I need to make to utilize one that has 200v and 12v instead?

No changes needed.

 

[Bel.kevin01]

No changes needed.

Thanks for the reply! One more question, I'm sure I could test this for myself and find out but I'm away for a few days. Whats the amperage of the original 200v and 9.5v secondaries? does it matter too much?

Cheers

 

[Delta Sigma]

Thanks for the reply! One more question, I'm sure I could test this for myself and find out but I'm away for a few days. Whats the amperage of the original 200v and 9.5v secondaries? does it matter too much?

Cheers

Is your question about the transformer ratings or the actual circuit draw at the transformer secondary?

 

[terry setter]

Most tube mics are biased at less than one milliamp on the B+, though some are up to double that. The heater current is easily found by looking at the data sheet for the tube your using. Of course, the higher the current delivery capability of your transformer, the less it's likely to audibly hum (due to physical vibration). It's not a problem to have a B+ secondary that is above 200V. Personally, I like to start with voltages at the output of the rectifiers that are AT LEAST twice the final needed voltages. I end up with VERY quiet supplies, even though I usually don't use a regulator on the B+. (Hint: I do put a zener on the output of the B+ that's rated for about 20 volts more than the operating B+ voltage. That protects from surges and also acts as an emergency brake if someone turns on the supply without a mic connected, or the tube fails, etc.)

 

[Bel.kevin01]

Is your question about the transformer ratings or the actual circuit draw at the transformer secondary?

Specifically curious about the stock transformers ratings.

 

[Bel.kevin01]

Most tube mics are biased at less than one milliamp on the B+, though some are up to double that. The heater current is easily found by looking at the data sheet for the tube your using. Of course, the higher the current delivery capability of your transformer, the less it's likely to audibly hum (due to physical vibration). It's not a problem to have a B+ secondary that is above 200V. Personally, I like to start with voltages at the output of the rectifiers that are AT LEAST twice the final needed voltages. I end up with VERY quiet supplies, even though I usually don't use a regulator on the B+. (Hint: I do put a zener on the output of the B+ that's rated for about 20 volts more than the operating B+ voltage. That protects from surges and also acts as an emergency brake if someone turns on the supply without a mic connected, or the tube fails, etc.)

Thanks! That's great info. I'm planning to use a transformer that has 200v 10mA, and 12v 1A secondary. I like the idea of the zener on the B+!