Stacking power supplies - Page 2

KevinHeem · 2nd April 2009, 09:52 PM

Thanks, can you simulate the circuit with higher values for C5 and C6 to see what happens?

KevinHeem · 2nd April 2009, 09:55 PM

NA

KevinHeem · 2nd April 2009, 09:58 PM

yes, get rid of the zeners altogether and your voltage will vary with supply.

carpenter · 2nd April 2009, 10:17 PM

Quote:

Originally posted by KevinHeem
Thanks, can you simulate the circuit with higher values for C5 and C6 to see what happens?

The problem with increasing the values of C5 and C6 is that high voltage caps are expensive. I'm trying to keep this thing affordable.

If you have a cap in mind that will do the trick, let me know...

KevinHeem · 2nd April 2009, 10:32 PM

Quote:

Originally posted by carpenter

The problem with increasing the values of C5 and C6 is that high voltage caps are expensive. I'm trying to keep this thing affordable.

If you have a cap in mind that will do the trick, let me know...

Ah yes, you're running in the 125v range, I'm just running in the 50v range. Really don't have anything in mind, have just been curios what changing these values would do. Thanks Carpenter

woody · 2nd April 2009, 11:17 PM

No replace r34 with a CCS such as a CCS diode using a 10ma CCS instead of the 15k resistor r34 then select a resistor value to use instead of a zener stack. In this case 10ma across a 4k resistor will give you a 40v across the 4k resistor. In this example
any input voltage between ~43v and ~143v (assuming a 10ma
CCs diode with a 100v complience rating) will give 40v across the
4k resistor.

carpenter · 2nd April 2009, 11:50 PM

Sounds interesting, Woody. I'll sim it and report back. Any particular CCS configuration?

dave_gerecke · 3rd April 2009, 02:47 AM

Hello Carpenter, I am looking at your circuit, and also your post about higher voltage caps being expensive. From the circuit, it looks like you are using 220uF caps, I am assuming they are electrolytics. These seems pretty cheap to me. As an example, I checked out Antique Electronic Supplies and they have 220uF caps rated for 300 VDC from Illinois Capacitor for $4.75ea.

Peace,

Dave

carpenter · 3rd April 2009, 06:19 AM

Hi Dave,

I appreciate your comments and suggestions. The problem with high voltage caps begins when you want high uF values. 220uF isn't too bad, but 20,000 uF gets to be serious business.

carpenter · 3rd April 2009, 07:36 AM

I did a bit of searching and found reasonably priced 1000uF electrolytics at Digi-Key. Panasonic caps are $3.57 each if I purchase in lots of 10. Quite doable.

The only cap that made a world of difference (according to the sim) was C5 and C2 (I'm re-posting the schematics in case something has changed).

I'm filtered down to just a tad over 1mV with a two stage regulator.

2nd April 2009, 11:50 PM	#17
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	Sounds interesting, Woody. I'll sim it and report back. Any particular CCS configuration? __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

3rd April 2009, 06:19 AM	#19
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	Hi Dave, I appreciate your comments and suggestions. The problem with high voltage caps begins when you want high uF values. 220uF isn't too bad, but 20,000 uF gets to be serious business. __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

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2nd April 2009, 09:52 PM	#11
KevinHeem diyAudio Member Join Date: Nov 2007	Thanks, can you simulate the circuit with higher values for C5 and C6 to see what happens?

2nd April 2009, 09:55 PM	#12
KevinHeem diyAudio Member Join Date: Nov 2007	NA

2nd April 2009, 09:58 PM	#13
KevinHeem diyAudio Member Join Date: Nov 2007	yes, get rid of the zeners altogether and your voltage will vary with supply.

2nd April 2009, 11:17 PM	#16
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	No replace r34 with a CCS such as a CCS diode using a 10ma CCS instead of the 15k resistor r34 then select a resistor value to use instead of a zener stack. In this case 10ma across a 4k resistor will give you a 40v across the 4k resistor. In this example any input voltage between ~43v and ~143v (assuming a 10ma CCs diode with a 100v complience rating) will give 40v across the 4k resistor.

3rd April 2009, 02:47 AM	#18
dave_gerecke diyAudio Member Join Date: Dec 2007 Location: Vermont	Hello Carpenter, I am looking at your circuit, and also your post about higher voltage caps being expensive. From the circuit, it looks like you are using 220uF caps, I am assuming they are electrolytics. These seems pretty cheap to me. As an example, I checked out Antique Electronic Supplies and they have 220uF caps rated for 300 VDC from Illinois Capacitor for $4.75ea. Peace, Dave