Thanks Fuling!
I thought almost the same, 100mH/3A DC.
What do you think about the operating voltage? +24V vould be enough?
Tyimo
I thought almost the same, 100mH/3A DC.
What do you think about the operating voltage? +24V vould be enough?
Tyimo
A couple of years ago I made an amp like that, 100mH 3A and 27V rails. I got over 30W out at full blast.
It never got past the prototype stage because of the required size of the heatsinks. I tried fan cooling but the fans made too much noise.
The benefit of using chokes instead of constant current sources is that we can cut the rail voltage down to 50%, the inductance swings the negative half with it´s stored energy.
This raises the maximum theoretical efficiency to 50% instead of 25%.
So, aim for at least 100mH and make sure that the choke can handle the DC (+ the AC swing, overrating this component is not a bad idea) and cut the voltage down to 50%.
It never got past the prototype stage because of the required size of the heatsinks. I tried fan cooling but the fans made too much noise.
The benefit of using chokes instead of constant current sources is that we can cut the rail voltage down to 50%, the inductance swings the negative half with it´s stored energy.
This raises the maximum theoretical efficiency to 50% instead of 25%.
So, aim for at least 100mH and make sure that the choke can handle the DC (+ the AC swing, overrating this component is not a bad idea) and cut the voltage down to 50%.
Thanks Fuling!
What about the choke's resistance? 0.5 -1 Ohm?
I would make a torroid choke from a transformator.
Tyimo
What about the choke's resistance? 0.5 -1 Ohm?
I would make a torroid choke from a transformator.
Tyimo
DCR: The lower the better, simply.
Stay away from toroids, they usually have no airgaps which are absolutely necessary to avoid core saturation from the DC.
Check this (long) thread, it has plenty of good info about choke loaded amps and how to make your own chokes:
http://www.diyaudio.com/forums/showthread.php?threadid=6338&highlight="first+ever+class+a"
Stay away from toroids, they usually have no airgaps which are absolutely necessary to avoid core saturation from the DC.
Check this (long) thread, it has plenty of good info about choke loaded amps and how to make your own chokes:
http://www.diyaudio.com/forums/showthread.php?threadid=6338&highlight="first+ever+class+a"
Thanks!
I already found it on the page 9-10-11. Very interesting.
I don't understand ..... Mr.Pass used also toroids for the ZV7.
Greets:
Tyimo
I already found it on the page 9-10-11. Very interesting.
I don't understand ..... Mr.Pass used also toroids for the ZV7.
Greets:
Tyimo
Are you sure it wasn't a C-core or something toroidish? It's physically impossible to have that much DC flowing in a choke that small without an air gap and not have near zero inductance, let alone the eddy currents setting it on fire 🙁
Mea Culpa Maxima!!😀
Yes, you are right!! I forgot that the ZV7 is balanced.
I get off from the torroids.....😉
Thanks and Greets
Tyimo
Yes, you are right!! I forgot that the ZV7 is balanced.
I get off from the torroids.....😉
Thanks and Greets
Tyimo
EI cores or gapped C cores is to go.
OTOH, in small amps there is not much benefit in using chokes.
Up to a certain power level it´s probably easier to find suitable heatsinks that can handle an ordinary CCS´ed follower than to find (or make) suitable chokes.
In bigger amps the efficiency obviously becomes more important.
OTOH, in small amps there is not much benefit in using chokes.
Up to a certain power level it´s probably easier to find suitable heatsinks that can handle an ordinary CCS´ed follower than to find (or make) suitable chokes.
In bigger amps the efficiency obviously becomes more important.
We won't actually get to discuss it in detail until the upcoming diyFEST on Aug 5. We'll have a better idea of where we want to go after that.
dave
dave
Would it be possible to use a possitive and negative supply with the Sewa if I change Q2 to it´s complementary?To get rid of C4 and C3.
Ryssen said:
9 time zones east, a big ocean, and the width of a continent away... you are most welcome to come 🙂
dave
output power calculation
Hi!
Could somebody tell me how can I calculate the output power of the choke loade SEWA?
120mH 0.5R Choke
+24V supply
8R load
24/8=3A bias
Thanks!
Tyimo
Hi!
Could somebody tell me how can I calculate the output power of the choke loade SEWA?
120mH 0.5R Choke
+24V supply
8R load
24/8=3A bias
Thanks!
Tyimo
Thanks Fuling!
But, what equation did you use??
For me 15W would be enough and if it is possible I would like to use it with Battery PSU! 😉
Greets:
Tyimo
But, what equation did you use??
For me 15W would be enough and if it is possible I would like to use it with Battery PSU! 😉
Greets:
Tyimo
I didn´t calculate anything, but the numbers are about the same as in a prototype amp I made a couple of years ago.
If you don´t need such high power, decrease the rail voltage and keep the current as high as possible.
All class A amps seems to like plenty of current, and most speakers likes amps that can deliver current.
Battery supply?
12V would be a bit low and 24 seems to be more than you need, so perhaps 3 x 6V?
OTOH, 12V (or 13,8V in reality) might be enough for about 10W, which is close enough to 15W and one 12V battery is much easier to charge than three 6V batterys.
If you don´t need such high power, decrease the rail voltage and keep the current as high as possible.
All class A amps seems to like plenty of current, and most speakers likes amps that can deliver current.
Battery supply?
12V would be a bit low and 24 seems to be more than you need, so perhaps 3 x 6V?
OTOH, 12V (or 13,8V in reality) might be enough for about 10W, which is close enough to 15W and one 12V battery is much easier to charge than three 6V batterys.