I am specifically referring to this post here: http://www.diyaudio.com/forums/solid-state/167545-500va-transfomer-3-secondaries-no-centre-tap-3.html#post2201205.
I didn't want to take the original thread too far off, so I opened this thread (@mods: please merge/delete/whatever however you please).
I found it annoyingly difficult to find center tapped xformers for a price that won't make me go broke. I was under the impression, that connecting the secondaries of two identical xformers would create the behaviour of a center tapped xformer. So is there no advantage to using two xformers in the aforementioned way?
Another catch: do I need to connect the secondaries in phase or 180° out of phase? 😕
I didn't want to take the original thread too far off, so I opened this thread (@mods: please merge/delete/whatever however you please).
I found it annoyingly difficult to find center tapped xformers for a price that won't make me go broke. I was under the impression, that connecting the secondaries of two identical xformers would create the behaviour of a center tapped xformer. So is there no advantage to using two xformers in the aforementioned way?
Another catch: do I need to connect the secondaries in phase or 180° out of phase? 😕
The original Crest 8001 used two transformers in series.
http://www.crestaudio.com/media/schematics/8001_schematic_set1.pdf
See page 5. Crest used two rectifier bridges because they needed two tiers of output voltage.
http://www.crestaudio.com/media/schematics/8001_schematic_set1.pdf
See page 5. Crest used two rectifier bridges because they needed two tiers of output voltage.
I did this!
I used this configuration here http://www.diyaudio.com/forums/soli...d-amplifier-out-junk-parts-4.html#post2181668(see photo), for not having the necessary transformer for testing purposes. I needed 24+24VAC, but had two 12+12VAC transformers.
It worked very fine, once both transformers were same type and specs. But the way I dit was a bit different from attached PDF: I linked them together in series before rectifier bridge.
You should try both cases, being aware that they should have the same output AC voltage, in order not to cause any difference between DC supply rails.
Regards,
Max.
I used this configuration here http://www.diyaudio.com/forums/soli...d-amplifier-out-junk-parts-4.html#post2181668(see photo), for not having the necessary transformer for testing purposes. I needed 24+24VAC, but had two 12+12VAC transformers.
It worked very fine, once both transformers were same type and specs. But the way I dit was a bit different from attached PDF: I linked them together in series before rectifier bridge.
You should try both cases, being aware that they should have the same output AC voltage, in order not to cause any difference between DC supply rails.
Regards,
Max.
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Dude,
If I read your cat. correctly, you have a transformer with just one 22.5 V winding tapped at 15,5 V (6.6 A) with about 150 VA total rating.
That might be a bit hard to find typical amplifier uses for. Then, maybe that's not what you want!
If I read your cat. correctly, you have a transformer with just one 22.5 V winding tapped at 15,5 V (6.6 A) with about 150 VA total rating.
That might be a bit hard to find typical amplifier uses for. Then, maybe that's not what you want!
forget the qsc schematic .... this doesnt use two transformers fro the same reason that you want to use them ...it is far more complicated than that
there is almost nothing wrong by using two of the same transformers to create a center tap ( while preserving phase issues )
in a previous thread it was mentioned by a forum member that is possible to have assymetrical clipping cause of that ... this can be possible stands as a statement but personaly i havent seen it hapening
regards sakis
there is almost nothing wrong by using two of the same transformers to create a center tap ( while preserving phase issues )
in a previous thread it was mentioned by a forum member that is possible to have assymetrical clipping cause of that ... this can be possible stands as a statement but personaly i havent seen it hapening
regards sakis
I don't plan on carrying that amp around much. It will be set up on my desk and stay there until for example I move house.
In order not to open another thread I wanted to ask a question on obtaining a ceter tap. I reently came across a stock of pcb transformers:
not very powerful but often handy for small DAC/electronic applications.
The xmfrs I have are 220v - 13 13 no center tap.
If I connect the inputs in parallel and the secondaries (careful to the phase) could I obtain a 13 -0 -13 transformer?
Thanks.
An externally hosted image should be here but it was not working when we last tested it.
not very powerful but often handy for small DAC/electronic applications.
The xmfrs I have are 220v - 13 13 no center tap.
If I connect the inputs in parallel and the secondaries (careful to the phase) could I obtain a 13 -0 -13 transformer?
Thanks.
Hi,
You tell us it has a 220Vac primary.
To connect the inputs in parallel you need to start with a dual primary. What are you going to parallel?
The secondary is 13 13 no centre tap.
Do you mean 0-13Vac, 0-13Vac = dual secondary with 4 connecting pins?
I think I can read:
230V 5VA
0 15V 0 15V
printed on the top panel.
That is likely to to be a 230:15+15Vac transformer.
Measured open circuit will likely be 18+18Vac to 20+20Vac
You tell us it has a 220Vac primary.
To connect the inputs in parallel you need to start with a dual primary. What are you going to parallel?
The secondary is 13 13 no centre tap.
Do you mean 0-13Vac, 0-13Vac = dual secondary with 4 connecting pins?
I think I can read:
230V 5VA
0 15V 0 15V
printed on the top panel.
That is likely to to be a 230:15+15Vac transformer.
Measured open circuit will likely be 18+18Vac to 20+20Vac
I am sorry....the picture was just for reference should have cleared that in the post
The secondary is 13vac + 13vac
the primary is 220v
Is there any way I can obtaina center tap by using multiple transformers like the one described?
The secondary is 13vac + 13vac
the primary is 220v
Is there any way I can obtaina center tap by using multiple transformers like the one described?
it... is very possible .... what you actually have to look at if the primary is 220 or 230 ... this actually is not a minor diference
if trafos are 220 rated runing them in 230 and often at nights 240 might be an issue and trafos will not make it in long run terms
if trafos are 220 rated runing them in 230 and often at nights 240 might be an issue and trafos will not make it in long run terms
Actually 230v I just had in mind our own national grid lines...they tend to drop close to 220v.
the trafos are 230v input 13+13 secondary
the trafos are 230v input 13+13 secondary
My guess is the transformer in the picture has a 2-pin input and 4-pin outputs. Connecting the two middle pins of the output gives +0- at a good 100mA or so.
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why ?
p.s. using two trafo's is what I plan to do in a project. It's mainly to use up junk trafo's that I have. But it gives me the means to wire the primary for Canada or UK in the future. It also allows me to distribute the weight better inside the chasis.
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