Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Feb Sat 24, 2018 1:28 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 692 posts ]  Go to page Previous  1 ... 25, 26, 27, 28, 29, 30, 31 ... 35  Next
Author Message
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 6:31 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Here is Flips 13v supply. What will need to be changed for use with the higher voltage?
Attachment:
13v supply.png
13v supply.png [ 42.06 KiB | Viewed 90 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 6:47 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Here is my idea, using what you guys showed me, and some hillbilly math.
Attachment:
13v supply.png
13v supply.png [ 36.81 KiB | Viewed 88 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 8:42 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8377
Location: Texas. USA
john8750 wrote:
Here is my idea, using what you guys showed me, and some hillbilly math.
Attachment:
13v supply.png
I'd put 2.5 uF in there. But then, I design so it's guaranteed to work with the worst case current consumption over the worst case AC line variation.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 8:43 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
john8750 wrote:
Pbpix wrote:
john8750 wrote:
Peter, I made up one of the CCS modules you use. Man, that's cool. Wish I would have done that. I may change them out, if I run out of things to do....

Good. Glad you like it.
It's certainly nice and compact that way. Isn't it? :-)




Heck yes. What voltage caps did you use? I have 25-35-and 50. Used 35's just because of the size. Would use 50's otherwise.
I should have used 450's in the power supply. They are just a little taller than the 400's.

Yes... I think I'm using 1000uf@ 35v or 50v

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 9:07 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
Hi John:

Good news !!!

I've solved the 145v AC power supply problem.

Instead of adding all the big dropping resistors.... just go back and leave R1 the 220 ohm as it is.

Here is a VERY simple and elegant solution.
Let's convert our voltage-doubler power supply to a ... capacitor-dropper & voltage-doubler combination.


Simply drop C3 down from 220uf ... to a 20uf . That's it!

The smaller cap will limit the maximum current to the load to 100ma.

You can try 20uf or 21 uf.
Measure the cap before you put it in to be sure it is not MORE than 20 uf

If you find that you need more.. try 21uf or 22uf max.

Be sure to measure the cap first ....because E-caps have a very wide variation from what is written on the side.

I have bench tested this using 20uf with a 3k dummy load.

I fed in 145vAC.
The B+ across my 3k dummy load was very close to 298v DC
(but if your output is a little different or too low go up 1uf or 2 uf )
you can use polarized E-caps or non polar AC film caps... doesn't matter as long as the cap is 160v or better.

Attachment:
145v ps change.jpg
145v ps change.jpg [ 63.11 KiB | Viewed 81 times ]

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 7:58 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
Here is my idea, using what you guys showed me, and some hillbilly math.
Attachment:
13v supply.png
I'd put 2.5 uF in there. But then, I design so it's guaranteed to work with the worst case current consumption over the worst case AC line variation.



Thanks Flip. I was wondering about that. I will make the change and test the circuit.
Of course there is no actual 540ohm stock resistor available. I actually calculated a resistance of 533.
And that was using your original circuit. So I will start with a close enough resistor, and go on from there.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 8:01 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Pbpix wrote:
Hi John:

Good news !!!

I've solved the 145v AC power supply problem.

Instead of adding all the big dropping resistors.... just go back and leave R1 the 220 ohm as it is.

Here is a VERY simple and elegant solution.
Let's convert our voltage-doubler power supply to a ... capacitor-dropper & voltage-doubler combination.


Simply drop C3 down from 220uf ... to a 20uf . That's it!

The smaller cap will limit the maximum current to the load to 100ma.

You can try 20uf or 21 uf.
Measure the cap before you put it in to be sure it is not MORE than 20 uf

If you find that you need more.. try 21uf or 22uf max.

Be sure to measure the cap first ....because E-caps have a very wide variation from what is written on the side.

I have bench tested this using 20uf with a 3k dummy load.

I fed in 145vAC.
The B+ across my 3k dummy load was very close to 298v DC
(but if your output is a little different or too low go up 1uf or 2 uf )
you can use polarized E-caps or non polar AC film caps... doesn't matter as long as the cap is 160v or better.

Attachment:
145v ps change.jpg




Very cool Peter. I will indeed make that change. And let you know how she works out. Thank you....

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 10:27 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
john8750 wrote:

Very cool Peter. I will indeed make that change. And let you know how she works out. Thank you....


At these specifically particular capacitor values you will get a good stable but fixed 300v B+ voltage/current.

However it will be somewhat dependent on the 145vAC input remaining steady.

If you anticipate some variations on the 145v input of +/- 5v AC you will see similar variations on the output B+.
So if you have 145vAC in you'll get 300vDC out.

But if you drop to 140vAC input your DC will drop to about 295v DC b+

So if you want to stay above 295v B+ then you can try using a 25uf cap or such which will bring up the B+ to 305v DC.
....so this will allow the AC input to drop by 5v and still give you 300v DC B+ out.

So... it's up to you to decide your minimum or the lowest B+ that's acceptable.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Tue 13, 2018 11:45 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
Ok... update:

So John, as per our telco today:

You found out, of course, that if you drop C3 to an even lower value like 10uf ... then everything else drops down too.
So now, with C3 at 10uf, you don't need to keep R1 at 220 ohms.
... and just as you experimented you dropped R1 to 50 ohms and still get 295v B+ output and R1 runs very cool as it's only dropping 5 volts at 1/2 watt.

Do me a favor and measure the ripple on the B+ now.

I think it will be about 20mv pp if your last filter cap is 820uf and around 40v pp if that last filter cap is 470uf.

So measure B+ with the scope set on AC input with a x1 probe and set your vertical gain input knobs down to about 10mv per box. You should see about 4 or 5 boxes high of ripple signal.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 1:01 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8377
Location: Texas. USA
john8750 wrote:
Pbpix wrote:
Hi John:

Good news !!!

I've solved the 145v AC power supply problem.

Instead of adding all the big dropping resistors.... just go back and leave R1 the 220 ohm as it is.

Here is a VERY simple and elegant solution.
Let's convert our voltage-doubler power supply to a ... capacitor-dropper & voltage-doubler combination.


Simply drop C3 down from 220uf ... to a 20uf . That's it!

The smaller cap will limit the maximum current to the load to 100ma.

You can try 20uf or 21 uf.
Measure the cap before you put it in to be sure it is not MORE than 20 uf

If you find that you need more.. try 21uf or 22uf max.

Be sure to measure the cap first ....because E-caps have a very wide variation from what is written on the side.

I have bench tested this using 20uf with a 3k dummy load.

I fed in 145vAC.
The B+ across my 3k dummy load was very close to 298v DC
(but if your output is a little different or too low go up 1uf or 2 uf )
you can use polarized E-caps or non polar AC film caps... doesn't matter as long as the cap is 160v or better.

Attachment:
145v ps change.jpg
Very cool Peter. I will indeed make that change. And let you know how she works out. Thank you....
That's a bad idea. At power peaks the amp will draw almost twice the current as it does at idle (25mA/tube).


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 1:47 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
Flipperhome wrote:
That's a bad idea. At power peaks the amp will draw almost twice the current as it does at idle (25mA/tube).

I was concerned about load variations but didn't know it would be THAT extreme.
How long do you believe the extra current draw moments will typically last? Will the very large filter cap of 820uf be enough reserve?
Do the CCS by-pass caps need to be more than 1000uf or is that enough reserve?

How does the "normal" unregulated pi-filter supply handle it. It must still drop the B+... no?

Perhaps a larger C3 and a larger R1 ... but not as much voltage as before?

Suggestions?

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 7:32 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Very strange thing here. I have exactly the same circuit components wired up that Flip and Peter have. You guys do a great design job, get it working perfectly. I duplicate the same circuit, it works, but all resistors get too hot.
Maybe we have different ideas of hot :?:

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 7:58 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Here is my B+ supply. Runs cool at 295volts. But, am concerned about what you guys think about a possible problem.
I would rather go back to a very hot R1, ventilate the thing. Mount the resistor outside? What do you suggest?
Attachment:
example.png
example.png [ 103.96 KiB | Viewed 48 times ]

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 10:17 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
I don't know John.. Remember there's no magic here... just Ohms law and simple math.
Nothing in this circuit, as shown, should be getting hot in any way. I'm running it exactly as shown and R1 is cool.

( I'm using a "3k" dummy load that actually measures 2950 ohms)

I you put these SAME parts together you should get the same results.
But sure to FIRST measure the component values to be sure you have the same thing.

If you build this set up EXACLY this way... then the R1 220 ohm will be dropping 22v @ 100ma so that's only 2.2 watts.

So if you measure 295v Dc on the output of R1... that means you should have around 317vDC on the input to R1.

Use two 10uf caps in parallel and measure them to be sure it's 20uf before testing.
You say you have a 20watt R1 ... so that should be plenty cool .. maybe just a tad warm.
Measure each component and measure and verify the 145v input. Be sure R1 is actually 220 ohms.
Image

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 11:03 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
I have about the same circuit now Peter. I have C3 at 10uf. And yes, I forgot to measure the actual values, but will. R1 is 100ohm. And I can live with the amount of heat. One difference could be that My parts are in the chassis. Could build up heat faster than in the open. And could have a difference in resistor types. I agree, no magic here, just east coast vs west coast.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 11:17 pm 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
I got the 13volt supply working. Here it is.
Attachment:
13v supply.png
13v supply.png [ 27.41 KiB | Viewed 44 times ]




Exactly what Flip designed for me.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Wed 14, 2018 11:25 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21854
Location: Haledon, NJ, usa
john8750 wrote:
I have about the same circuit now Peter. I have C3 at 10uf. And yes, I forgot to measure the actual values, but will. R1 is 100ohm. And I can live with the amount of heat. One difference could be that My parts are in the chassis. Could build up heat faster than in the open. And could have a difference in resistor types. I agree, no magic here, just east coast vs west coast.

Nah... I disagree.
Being in the chassis cannot cause what you were describing as "blistering heat"

Try two 10uf caps(20uf) and R1 as 220 ohm.
Measure the volts into R1 317v and out as 295v.
.. and if you use a 220 ohm for R1 ... It cannot get hot.
so please do that set up let me know if it gets hot.... it should be just above room temp.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Thu 15, 2018 12:57 am 
Member
User avatar

Joined: Nov Sat 26, 2011 4:09 am
Posts: 8377
Location: Texas. USA
john8750 wrote:
Here is my B+ supply. Runs cool at 295volts. But, am concerned about what you guys think about a possible problem.
I would rather go back to a very hot R1, ventilate the thing. Mount the resistor outside? What do you suggest?
Attachment:
example.png
I think you'd be better off using the right transformer.

Class AB doesn't have a 'constant current' draw so as power reaches max B+ is going to droop. It won't droop as much as the raw numbers suggest, because it'll be transient peaks, but it will still droop some and that's made worse by you using such a low idle current. That magnifies the difference between 0 (idle) and max power and reduces the amount of power the amp can produce before it goes into 'B' operation. And then there's the issue of ripple current through C1. 10 uF and 20 uF caps are rated 70-130 mA (for low impedance types) and simply can't handle the 380 mA or so it takes to run the circuit. It might work for a while but it will fail prematurely.

As for the 'heat', it's certainly being aggravated by being in a confined space with a lack of air circulation.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Thu 15, 2018 1:39 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Flipperhome wrote:
john8750 wrote:
Here is my B+ supply. Runs cool at 295volts. But, am concerned about what you guys think about a possible problem.
I would rather go back to a very hot R1, ventilate the thing. Mount the resistor outside? What do you suggest?
Attachment:
example.png
I think you'd be better off using the right transformer.

Class AB doesn't have a 'constant current' draw so as power reaches max B+ is going to droop. It won't droop as much as the raw numbers suggest, because it'll be transient peaks, but it will still droop some and that's made worse by you using such a low idle current. That magnifies the difference between 0 (idle) and max power and reduces the amount of power the amp can produce before it goes into 'B' operation. And then there's the issue of ripple current through C1. 10 uF and 20 uF caps are rated 70-130 mA (for low impedance types) and simply can't handle the 380 mA or so it takes to run the circuit. It might work for a while but it will fail prematurely.

As for the 'heat', it's certainly being aggravated by being in a confined space with a lack of air circulation.



Well. I don't mind making a whole new chassis with metal, and more inside room. I can order a different transformer. I tried reversing primary with the secondary and got 107volts unloaded. I have a 50watt isolation transformer, don't think that's enough.
If you guys think I should, I will.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
 Post subject: Re: 6V6 amp project- with a twist
PostPosted: Feb Thu 15, 2018 1:50 am 
Member
User avatar

Joined: Dec Mon 29, 2014 9:39 pm
Posts: 3887
Location: Los Angeles
Pbpix wrote:
john8750 wrote:
I have about the same circuit now Peter. I have C3 at 10uf. And yes, I forgot to measure the actual values, but will. R1 is 100ohm. And I can live with the amount of heat. One difference could be that My parts are in the chassis. Could build up heat faster than in the open. And could have a difference in resistor types. I agree, no magic here, just east coast vs west coast.

Nah... I disagree.
Being in the chassis cannot cause what you were describing as "blistering heat"

Try two 10uf caps(20uf) and R1 as 220 ohm.
Measure the volts into R1 317v and out as 295v.
.. and if you use a 220 ohm for R1 ... It cannot get hot.
so please do that set up let me know if it gets hot.... it should be just above room temp.



I did it.
C3 is two 10uf ecaps. Reads 21.02uf.
R1 is a 220ohm 20watt sand resistor. Reads 217.6ohms.
ac input=146.7vac.
At C3/diode junction=139.7vac.
C1/R1 junction=361vdc.
B+ is 336vdc, connected to the circuit and playing music.

_________________
John Smith, over and out.
If I did something right, I made a mistake.


Top
 Profile  
 
Post New Topic Post Reply  [ 692 posts ]  Go to page Previous  1 ... 25, 26, 27, 28, 29, 30, 31 ... 35  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: Audioman, Google [Bot] and 2 guests



Search for:
Jump to:  






















Privacy Policy :: Powered by phpBB