Squeezebox power supply - Page 3

pinkmouse · 13th September 2006, 06:22 PM

The LM338 looks like the best bet then. Get one in the TO3 can and put it on a decent heatsink, as the most likely easily available trannie for that current will be 9V.

FastEddy · 13th September 2006, 06:58 PM

gsuser: " ... I want to build a new linear one. ..."

pinkmouse: " ... [and get an LM338 in a] TO3 can and put it on a decent heatsink ..."

Seconded, passed by the quarum and put in the out box ... now get to work ...

gsuser · 13th September 2006, 08:14 PM

Thanks

Any advice for the other components values in this shematic ?

angchuck · 13th September 2006, 08:34 PM

You would only need the top half, the part with the LM317. You can also use the LM338, but i don't think you need the headroom.

I have a Roku soundbridge with a Meanwell smps with some filter caps. A slight improvement, more discernable with headphones. Probably going linear would have more positive results. All the best.

Chuck.

angchuck · 13th September 2006, 08:36 PM

oh i forgot!

http://www.muzique.com/schem/lm317.htm

pinkmouse · 13th September 2006, 09:23 PM

Here's one I made earlier. Set R1 and R2 as per angchuck's link.

FastEddy · 13th September 2006, 09:45 PM

... at C4 is a great idea = stabilizes the voltage reference.

gsuser · 14th September 2006, 07:16 AM

OK, thanks, it's more precise for me now.
It will be Pinkmouse's shematic, with his recommandation of the LM338 in a TO3 can. Angchuck'link gives me 220 Ohms for R1, and 660 Ohms for R2 withe the LM317. Will it be the same for the LM338 ?
Can you help me with the choice of the transformer ? toroïdal or other ? 9V 25VA ?

FastEddy · 14th September 2006, 03:04 PM

... I would be quite satisfied with one of these myself.

" ... It will be Pinkmouse's shematic, with his recommandation of the LM338 in a TO3 can. Angchuck'link gives me 220 Ohms for R1, and 660 Ohms for R2 withe the LM317. Will it be the same for the LM338 ? ..." Yes, similar circuits / chips that use the same basic resistor ratios.

" ... Can you help me with the choice of the transformer ? toroïdal or other ? 9V 25VA ? ..."

Preference would be the torridal type, but there is a plathora of "standard" transformers to chose from. Your target voltage should closely match the specifications for best results from the LM338 = 9 to 15 VDC from the diode bridge (Vin for the LM338) ... so a 9 Volts AC secondary times 1.414 ~= 12.xx volts (the peak voltage from the diode bridge = input AC volts times square root of 2 ~= 1.414 [... which would make this an almost ideal 12 Volt battery charges as well]).

As for the transformer power rating, I like a two to one safety ratio (others may have other preferences) ... so, output power = volts DC times current = 5 VDC times 2.x Amps ~=12 to 14 Watts ... times two for safety and lower heat ~= 25 Watts = 25 VA.

gsuser · 14th September 2006, 03:49 PM

Thanks for these precisions, FastEddy, I can now begin. I'll post a picture when done

13th September 2006, 06:22 PM	#21
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	The LM338 looks like the best bet then. Get one in the TO3 can and put it on a decent heatsink, as the most likely easily available trannie for that current will be 9V. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

13th September 2006, 06:58 PM	#22
FastEddy diyAudio Member Join Date: Jun 2006 Location: North Californie	seconded ... gsuser: " ... I want to build a new linear one. ..." pinkmouse: " ... [and get an LM338 in a] TO3 can and put it on a decent heatsink ..." Seconded, passed by the quarum and put in the out box ... now get to work ...

13th September 2006, 09:45 PM	#27
FastEddy diyAudio Member Join Date: Jun 2006 Location: North Californie	That snubbing cap ... ... at C4 is a great idea = stabilizes the voltage reference.

14th September 2006, 03:04 PM	#29
FastEddy diyAudio Member Join Date: Jun 2006 Location: North Californie	close to prefect ... ... I would be quite satisfied with one of these myself. " ... It will be Pinkmouse's shematic, with his recommandation of the LM338 in a TO3 can. Angchuck'link gives me 220 Ohms for R1, and 660 Ohms for R2 withe the LM317. Will it be the same for the LM338 ? ..." Yes, similar circuits / chips that use the same basic resistor ratios. " ... Can you help me with the choice of the transformer ? toroïdal or other ? 9V 25VA ? ..." Preference would be the torridal type, but there is a plathora of "standard" transformers to chose from. Your target voltage should closely match the specifications for best results from the LM338 = 9 to 15 VDC from the diode bridge (Vin for the LM338) ... so a 9 Volts AC secondary times 1.414 ~= 12.xx volts (the peak voltage from the diode bridge = input AC volts times square root of 2 ~= 1.414 [... which would make this an almost ideal 12 Volt battery charges as well]). As for the transformer power rating, I like a two to one safety ratio (others may have other preferences) ... so, output power = volts DC times current = 5 VDC times 2.x Amps ~=12 to 14 Watts ... times two for safety and lower heat ~= 25 Watts = 25 VA.

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13th September 2006, 08:34 PM	#24
angchuck diyAudio Member Join Date: Dec 2005 Location: Silly'pore	You would only need the top half, the part with the LM317. You can also use the LM338, but i don't think you need the headroom. I have a Roku soundbridge with a Meanwell smps with some filter caps. A slight improvement, more discernable with headphones. Probably going linear would have more positive results. All the best. Chuck.

13th September 2006, 08:36 PM	#25
angchuck diyAudio Member Join Date: Dec 2005 Location: Silly'pore	oh i forgot! http://www.muzique.com/schem/lm317.htm

14th September 2006, 07:16 AM	#28
gsuser diyAudio Member Join Date: Aug 2006	OK, thanks, it's more precise for me now. It will be Pinkmouse's shematic, with his recommandation of the LM338 in a TO3 can. Angchuck'link gives me 220 Ohms for R1, and 660 Ohms for R2 withe the LM317. Will it be the same for the LM338 ? Can you help me with the choice of the transformer ? toroïdal or other ? 9V 25VA ?

14th September 2006, 03:49 PM	#30
gsuser diyAudio Member Join Date: Aug 2006	Thanks for these precisions, FastEddy, I can now begin. I'll post a picture when done

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