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Old 22nd January 2010, 02:32 PM   #881
Salas is offline Salas  Greece
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That's a 12VCT isn't it? Its either 24VCT or 12+12 it takes.
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Old 22nd January 2010, 02:43 PM   #882
udailey is online now udailey  United States
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Yep, youre right. I messed that up on mine to. Ended up buying two center tapped because I just looked at the 12V rather than the fact that they are adding the two values to get 12. Plus it doesnt have 2 voltage outputs at the same time anyway. Should have looked a lot closer. The 12V or 6V depends on that being series or parallel so its does not have two output voltages at once. Sorry about that.
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Old 22nd January 2010, 02:46 PM   #883
udailey is online now udailey  United States
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Wonder if this one would help him.
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They claim "110 volt AC input with 2.5, 8, 12, 16 and/or 24 volt AC outputs (called "taps"). We add a line cord for easy hook up. Also works on 220VAC"
And they say you can use all tap voltages at once.
Uriah
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Old 22nd January 2010, 03:09 PM   #884
cedricb is offline cedricb  Europe
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Thanks guy! I'll have a look for the transformer...

@Salas, can you check the Ampere used by your own DCB1 please? ...so during my transformer (with multiple secondary) search, I could take the correct rating...
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Old 22nd January 2010, 03:29 PM   #885
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by udailey View Post
Wonder if this one would help him.
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ehh, shouldnt it be center tapped, doesnt look like one

It says "taps", not "center taps"
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Old 22nd January 2010, 03:50 PM   #886
udailey is online now udailey  United States
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Been looking for a real option but I keep obviously misinterpreting the taps. Makes sense Tinitus. I give. Suppose I can check digikey real quick.
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Old 22nd January 2010, 04:01 PM   #887
udailey is online now udailey  United States
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Digi-Key - MT3143-ND (Manufacturer - PLT20-32-130B)
It has a 27.5VAC CT AND the 9.3V secondary that could be regulated. The 27.5VCT could be used for the DCB1. Its a little high but not by much. With nearly no load it might come in higher voltage but a few watts of resistance might help that. Its the closest I could find on digikey. Which still leaves wondering if it works for VCCS as well.
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Old 22nd January 2010, 10:03 PM   #888
njepitt is offline njepitt  United Kingdom
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Hi Guys,

Thought I'd post a progress report.

1. I did the discrete regulator circuit I mentioned in post #865, following the advice given in the posts immediately after. After fiddling around with choosing LEDs, the best I could get was 8.54 and -8.34 VDC, which is a little low when you want +/- 9V, but within reasonable. (I'd rather err on the low side than err on the high side and blow a jfet...) If I wanted to fiddle around selecting leds some more I could probably get it more equal, but I'm not sure it's worth the bother, especially when you remember that I have output caps on it, and it's mainly intended as a test bed. On the other hand, the sound is FAR better than the 7809/7909 reg circuit I was using to test the heat dissipation. I expected some improvement, but I just finished listening to Mahler's 8th on my office system and found the improvement remarkable. OK, the system can't handle the organ, and the PSU in the preamp won't change that, but the improvement was most noticable in the quiet passages, where the soprano and mezzo voices have to be clearly separated (and positioned) from the rest of the (huge) orchestra. I found the difference from the earlier PSU and indeed from my other diy B1 quite striking... (Of course, now I should go back and do a proper AB comparison...)

2. I also followed Salas' suggestion and switched out the 3v9 zener for a LED pair in the big preamp. I tested various pairs until I got exactly the right voltage, so no resistor necessary, but the kids haven't given me a chance to listen to it yet... I still need to plan out the power supply for the active filters I'm doing, which I will likely do (following a suggestion of ZenMod on another thread) using one large current source feeding separate shunts at each buffer. (A total of 10 shunts... ) With this in mind, this thread may be a good place to ask about people's experiences using jfets other than 2SK170... As juma pointed out (elsewhere) I could use the BF862, but it would likely need cascoding, which is OK (if I understand correctly) but increases complexity in an already complex project. So I am on the lookout for other solutions, since 2SK170 are hard to come by down here and are expensive to import. As a sub-question, are the low-noise properties of the 2SK170 more important in the current source than the shunt, perhaps? Any thoughts?

Cheers

Nigel
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Old 22nd January 2010, 10:25 PM   #889
Salas is offline Salas  Greece
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I am happy that you like the sonics too. Look for 2SK117.
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Old 22nd January 2010, 10:48 PM   #890
Salas is offline Salas  Greece
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Quote:
Originally Posted by cedricb View Post
Thanks guy! I'll have a look for the transformer...

@Salas, can you check the Ampere used by your own DCB1 please? ...so during my transformer (with multiple secondary) search, I could take the correct rating...
Its what the 2 CCS draw, relays, plus losses in the Tx and rectification. Depends on how hard you run the CCS, other auxiliary circuits like the realys or LSPD if used, add 20% on top of that as min. I would double that for comfort.
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