Transformer for Zen V4?

G · 23rd October 2002, 10:55 PM

Would a 385 VA transformer with two 38 volt secondaries work for the unregulated supply diagrammed in the Zen V4 article? Do I need to change the supply circuit to use this transformer? Thanks.

G

Tazzy · 24th October 2002, 05:18 AM

38v should be okay. Use the secondaries parallel, that should give you 38 - 0 @ 770VA (instead of 38 - 0 - 38 @ 385 VA).

john-china · 24th October 2002, 05:25 AM

i think 385va with two 38vac secondaries, only get 385/2 va with 0--38vac.

UrSv · 24th October 2002, 07:10 AM

If it is a 385 VA transformer with two secondaries at 38 VAC then the two secondaries in parallell will give you a single 38 VAC at 385 VA. This will in turn correspond to roughly 50-52 VDC (single rail) after rectification and with load. The voltage may be slightly higher than the one with a 36 VAC transformer as stated in the article which will run your regulator slightly warmer but everything is well within limits IMHO.

This is pushing it a little for a stereo ZV4 (which would be happier with say 500+ VA)but will most likely work OK with the transformer running a little bit warm which is OK for some and unacceptable for others...

Tazzy,
the rating for the transfomer is 385 VA (provided that is correct) which means 385 VA for the WHOLE transformer which gives 192.5 VA per secondary which then makes available the whole 385 VA when using them in parallell for the single rail output.

/UrSv

Tazzy · 24th October 2002, 08:42 AM

Thanks for the information!

I thought that my Amplimo transformers where 300VA on each secondairy... turns out they are aprox 150VA and 300VA in total

miguel2 · 24th October 2002, 09:09 AM

I am using a 45-0-45 750VA transformer (in paralel) that gives after rectification 65V. It is a bit too much and the FET of the PSU runs warm. I think it is best to use a IRFP240 or something like that here, because of the extra heat.

G · 24th October 2002, 10:44 AM

Thanks for the info guys. It looks like I will be spending more on transformers than I thought.

G

23rd October 2002, 10:55 PM	#1
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Transformer for Zen V4? Would a 385 VA transformer with two 38 volt secondaries work for the unregulated supply diagrammed in the Zen V4 article? Do I need to change the supply circuit to use this transformer? Thanks. G __________________ Gavin

24th October 2002, 05:25 AM	#3
john-china diyAudio Member Join Date: Feb 2001 Location: where fair living	i think i think 385va with two 38vac secondaries, only get 385/2 va with 0--38vac. __________________ Maybe i should not be lazy again

24th October 2002, 10:44 AM	#7
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	Thanks for the info guys. It looks like I will be spending more on transformers than I thought. G __________________ Gavin

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24th October 2002, 05:18 AM	#2
Tazzy diyAudio Member Join Date: Jul 2002 Location: Netherlands	38v should be okay. Use the secondaries parallel, that should give you 38 - 0 @ 770VA (instead of 38 - 0 - 38 @ 385 VA).

24th October 2002, 07:10 AM	#4
UrSv diyAudio Member Join Date: Jan 2002 Location: Sweden	If it is a 385 VA transformer with two secondaries at 38 VAC then the two secondaries in parallell will give you a single 38 VAC at 385 VA. This will in turn correspond to roughly 50-52 VDC (single rail) after rectification and with load. The voltage may be slightly higher than the one with a 36 VAC transformer as stated in the article which will run your regulator slightly warmer but everything is well within limits IMHO. This is pushing it a little for a stereo ZV4 (which would be happier with say 500+ VA)but will most likely work OK with the transformer running a little bit warm which is OK for some and unacceptable for others... Tazzy, the rating for the transfomer is 385 VA (provided that is correct) which means 385 VA for the WHOLE transformer which gives 192.5 VA per secondary which then makes available the whole 385 VA when using them in parallell for the single rail output. /UrSv

24th October 2002, 08:42 AM	#5
Tazzy diyAudio Member Join Date: Jul 2002 Location: Netherlands	Thanks for the information! I thought that my Amplimo transformers where 300VA on each secondairy... turns out they are aprox 150VA and 300VA in total

24th October 2002, 09:09 AM	#6
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	I am using a 45-0-45 750VA transformer (in paralel) that gives after rectification 65V. It is a bit too much and the FET of the PSU runs warm. I think it is best to use a IRFP240 or something like that here, because of the extra heat.

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