Inductor Circlotron

carpenter · 17th November 2009, 04:31 PM

I got the inspiration for this Circlotron circuit from John Broskie's website: Tube Cad Journal. My version is a cascoded, balanced pair with center tapped chokes on both ends of the power supply. It seems to sim OK. Would love some input.

juma · 09:08 PM

It's an interesting balanced amp, but there is no "circle" in it, it's not a circlotron

You got just one PS and it's ground-referenced. Circlotron is basically a balanced push-pull with load across the bridge (as in Wien bridge, not as in "bridged amp"). Like this:

carpenter · 17th November 2009, 10:05 PM

I'll find article tonight after work. The large coupling caps become the second PS according to John's reasoning.

juma · 17th November 2009, 11:05 PM

Please do, I would like to read it. Broskie's explorations are great reading.

carpenter · 18th November 2009, 12:12 AM

The guy certainly has an imagination. Love his stuff.

carpenter · 18th November 2009, 03:12 AM

Here's the link: Safe vacuum tube amplifier design

juma · 18th November 2009, 08:59 AM

Yes, inductors make them float.

Do you plan to build it ?

carpenter · 03:33 PM

Yes, I do plan to build upon this concept. I already have constructed a balanced, cascoded mosfet/power jfet amp similar in design minus the top choke and coupling caps. Basically, all I need to do is add the choke and caps and I'm in-like-flint.

In my sims I noticed that it's very important to have a small value resistor on the lower choke center tap. The LU1014Ds would fry otherwise. Also, a couple volts from a negative power supply seem to improve the wattage curve on the jfets.

What's cool is that it'll drive a 2 ohm load and deliver 100 watts, or more, in the process.

BTW, I should mention: the mosfets count must be quadrupled at a minimum.

Oh, and it takes 10 volts on the inputs to achieve 120 watts output.

carpenter · 18th November 2009, 03:54 PM

I just noticed that I used the incorrect value resistors on the inputs/ground resistor. They should read 100k, not 100. Also, if the mosfet count is increased, they should receive 0.1 ohm resistors at their source pins to insure proper current sharing.

EUVL · 18th November 2009, 04:40 PM

It is not that by the time you spend enough money to get reasonable chokes and PSU caps, you could also have used the same money for two floating Tx and caps, etc. ?

Patrick

17th November 2009, 10:05 PM	#3
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	I'll find article tonight after work. The large coupling caps become the second PS according to John's reasoning. __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

18th November 2009, 12:12 AM	#5
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	The guy certainly has an imagination. Love his stuff. __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

18th November 2009, 03:12 AM	#6
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	Here's the link: Safe vacuum tube amplifier design __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

18th November 2009, 03:15 PM	#8
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	Yes, I do plan to build upon this concept. I already have constructed a balanced, cascoded mosfet/power jfet amp similar in design minus the top choke and coupling caps. Basically, all I need to do is add the choke and caps and I'm in-like-flint. In my sims I noticed that it's very important to have a small value resistor on the lower choke center tap. The LU1014Ds would fry otherwise. Also, a couple volts from a negative power supply seem to improve the wattage curve on the jfets. What's cool is that it'll drive a 2 ohm load and deliver 100 watts, or more, in the process. BTW, I should mention: the mosfets count must be quadrupled at a minimum. Oh, and it takes 10 volts on the inputs to achieve 120 watts output. __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com Last edited by carpenter; 18th November 2009 at 03:33 PM.

18th November 2009, 03:54 PM	#9
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	I just noticed that I used the incorrect value resistors on the inputs/ground resistor. They should read 100k, not 100. Also, if the mosfet count is increased, they should receive 0.1 ohm resistors at their source pins to insure proper current sharing. __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com


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17th November 2009, 11:05 PM	#4
juma diyAudio Member Join Date: Nov 2005 Location: Zemun	Please do, I would like to read it. Broskie's explorations are great reading.

18th November 2009, 08:59 AM	#7
juma diyAudio Member Join Date: Nov 2005 Location: Zemun	Yes, inductors make them float. Do you plan to build it ?

18th November 2009, 04:40 PM	#10
EUVL diyAudio Member Join Date: Oct 2003	It is not that by the time you spend enough money to get reasonable chokes and PSU caps, you could also have used the same money for two floating Tx and caps, etc. ? Patrick

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