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Bruno Putzeys Balanced Preamp - Group Buy Part 3

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#162
To burkm:
Be carefull when ordering 22uF and 1000uF Elna Silmics, former should be 25V (for 5mm diameter and 2mm pitch, namely RFS-25V220ME3#5) and latter doesn't exist for 10mm diameter. For bipolar, Elnas are only available on ebay so maybe nichicon ES can be used. BOM should be corrected to avoid further confusion.
 
#165
@miksi

You are correct, the stated 1000uF / 25V (D=10 mm, leads=5mm) part as stated in the BOM is not available from Elna.
I found Nichicon UKW1E102MPD http://www.mouser.de/ProductDetail/...=sGAEpiMZZMtZ1n0r9vR22e0BBN1kF1oijK76WbYHinE=
and Nichicon UKT1E102MPD http://www.mouser.de/ProductDetail/...GAEpiMZZMtZ1n0r9vR22e0BBN1kF1oisRs%2bocA7HE8=

The stated 22uF / 63V part is not correct in the BOM either, because of non fitting dimensions. What I found (D=5 mm, leads=2mm) is the Nichicon UKW1J220MDD
http://www.mouser.de/Search/Product...DDvirtualkey64700000virtualkey647-UKW1J220MDD

For the bipolar type 10uF / 50V (D=6.3mm, leads=2.5mm) the BOM has the wrong ratings and dimensions too. I found Nichicon UVP1H100MED
http://www.mouser.de/ProductDetail/...=sGAEpiMZZMtZ1n0r9vR22doNkPAgsBxuMAPP7aFCyVw=
and Nichicon UEP1H100MED http://www.mouser.de/ProductDetail/...=sGAEpiMZZMtZ1n0r9vR22YT02h/38WmxKOOhQYf4hUo=
and
Panasonic ECE-A1HN100U
http://www.mouser.de/ProductDetail/...=sGAEpiMZZMtZ1n0r9vR22RyzzjEKRzqKCBE3xXAr6RU=
 
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#171
burkm said:
Anyone have a suggestion for a specific power transformer type ?
Looked at 2 x 12.6V secondary but its not easy to find a supplier.
Click to expand...
12.6Vac is not a standard
Try 12Vac either dual secondary 0-12, 0-12Vac, or centre tapped 12-0-12Vac
If you buy a toroid, you can add 5 to 10 extra turns to each half of the secondary to adjust the voltage upwards slightly.
 
#175
AndrewT said:
12.6Vac is not a standard
Try 12Vac either dual secondary 0-12, 0-12Vac, or centre tapped 12-0-12Vac
If you buy a toroid, you can add 5 to 10 extra turns to each half of the secondary to adjust the voltage upwards slightly.
Click to expand...

I looked at what I found by a quick search.
What makes me hesitate ordering a transformer with standard double secondary winding 12VAC - 0 right now is, that this comes up to: 12 x 1.4 - ~0.5 V (rectifier) - ~0.2V (voltage drop 1st 2R2) - ~0.2 (voltage drop 2nd 2R2) per secondary winding in front of the Hypex regulators, which sums up to about 15.9 VDC input voltage at either 115 / 230 VAC primary. If one takes into consideration a 5% drop on the primary voltage (115/230VAC) one would end up with 12 * 0.95 * 1.4 (- 0.5 - 0.2 - 0.2) = 15.06 or appr. 15VDC, which is the minimum input voltage listed for the Hypex regulators to operate inside specifications. This seems to me somewhat "critical"...

Am I missing something here ?

Adding additional secondary windings on a standard toroid is no option for me, if I buy one.
 
#176
You are not missing anything.
I have already reported the problem with the hypex regulators and the recommeneded 12Vac transformer.

The Hypex regulators run hot if you use more than 12Vac and very hot if you use 15Vac.
But a 230:12+12Vac when operating on 216Vac will run the regulators very close to drop out.
This is part down to the melf resistors used to slow down the charging of the on board smoothing capacitance.
It is also down to the very variable current draw due to operating the three relays from the regulated supply.

That's why I reported quite a while back that a little bit more than 12Vac would be more suitable.

On my second board, I considered whether to move the PSU off board, or to use heatsink cooled 3pin regulators, or to take the relay supplies from a separate DC supply.
Three choices, I still have to make. A bit of experimentation is called for to see which could be the easiest implementation.
As is, it fails to meet my standards.
 
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#177
Hypex behavior with already regulated supply

Hi,

I have a good linear PSU +/- 15VDC ( 2 x 0.63A, already regulated , 2x2200µF) , that can be easily adjusted from 12 to 20VDC.
I'd like to first test BP's preamp with it.
How does the Hypex (and BPBP) behave with that type of power feed on J6 ?
What is the best voltage to use on J6 in my case ?

Thanks a lot !

JMK
 
#178
Hi AndrewT,

wouldn't it then be feasible, to use one of those readily available 15VDC (+/- adjustable) rail switching PSUs, which deliver an adjustable DC output voltage and could be adjusted to i.e. 15.5 V DC ? Two of those (1A) connected and one would have a symmetrical +/- 15.5 VDC supply feeding the Hypex regs. Some SMD capacitor across the 1000 uF electrolytes to reduce switching noise and one would be fine at just a bit more in price like a toroid...
 
#180
I looked at a Meanwell rail PSU DR-15 15VDC / 1A. They sell for about EUR 14 incl. VAT over here in Germany. They have a wide range primary input and can be finely trimmed on the output side. Because they are industrial components, they feature all sorts of output protection, are 100% burned in and MTBF is more than 1.000.000 hours...

http://media.it-tronics.de/Datasheets/Power_Supplies/MeanWell/DR-15.pdf

PS.: One question remains if they are installed in the same case as the BPBP. What about switching noise polluting the output of the pre amp electrically ? I wouldn't want another case just for the PSU...
 
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