Hi, But he always included end bells on his transformers, no? So, ? ? ?
On another subject...
Finding 10000uF, 25v or 35v, high temp (105C), long life, low ESR, high ripple v caps for filament reg raw supplies, I spent some two hours this afternoon looking...twern't easy. I looked at Parts Connexion and Mouser. Nothing at Parts Connexion, the closest they had was a Nichicon KG that was good for all except life was 1000 hours and high temp was 85C.
At Mouser, I found two good ones that were in stock and satisfied all of the other requirements:
1. https://www.mouser.com/ProductDetail/EPCOS-TDK/B41505A7109M000?qs=brqxNzf12%2BIlovwMQUiFJA==
2. https://www.mouser.com/ProductDetail/KEMET/PEH536JC-E5100M3?qs=fAHHVMwC%2Bbi2gzM2w%2BwRkQ==
Having found those, I gave up my search for today.
Does anyone have other alternatives? Thoughts?
Best, RC
Is this for 26 or 2P29L?
Either way, really, try two of these per rail CRC:
https://www.digikey.com/en/products/detail/epcos-tdk-electronics/B41252A5229M000/3493671
If for 2P29L, and your secondary voltage is low enough a 16V part should be a bit cheaper:
https://www.digikey.com/en/products/detail/epcos-tdk-electronics/B41231C4229M000/3493609
Regards,
John
I am building for 2P29L according to Rod's build note for 26 and 4P1L in filament bias, https://lyrima.co.uk/pdf/FilamentBias_Supply.pdf. I have had conversation with Rod in which he indicated that the build for 2P29L could be just like that for 4P1L, so that is what I am pursuing.
Since my original query about this I have found that Digi-Key has stock of the EPCOS 10000uF 25v 105C 5000Hr, PN B41505A5109M000, @ $5.15 each. I'm working on an order for those. Thank you for your suggestions. Best, RC
I prefer the 2P29L to the 26. But even better are the 10Y and 46. I just built all three. The 10Y is more smooth and "pleasant", the 46 is very clear and neutral. The 2P29L is somewhere in between - quite neutral compared to the warmish 26. I also tried the 47 in the 46 line stage and it wasn't as good as the 46. about the same level as the 2P29L, maybe a bit clearer and brighter but I don't think you gain much if anything. The 2P29L is very good, the 10Y and 46 are just a bit better, both quite addictive.
My suggestion was for suggestion was for 22000uF caps, as the difference in ripple reduction between 22mF and 10mF is worth considering at these low voltages—especially considering the cost is the same.
Try it out in PSUD2, see what you think.
Regards,
John
Since there is a flurry of activity here, I have a question.
For those of you who have successfully gotten the 2P29L up and running hum-free:
What specific make and model if transformer are you using for the filament supply?
i’ve chased down my hum issues to the filament transformers (with Rod’s help.)
I’ve been using batteris, which I like the sound of, but I’m tired of charging them over and over and over.
Thanks in advance for your replies!
Regards,
John
For those of you who have successfully gotten the 2P29L up and running hum-free:
What specific make and model if transformer are you using for the filament supply?
i’ve chased down my hum issues to the filament transformers (with Rod’s help.)
I’ve been using batteris, which I like the sound of, but I’m tired of charging them over and over and over.
Thanks in advance for your replies!
Regards,
John
I've ended up using anode resistors. Still the purest load to my ears with the best tonal quality for acoustic instruments. I listen to a lot of classical and opera. So B+ is 285V to 300V. Anode resistor is 15K for 10Y and 2P29L, and 12K for 46. Current is around 12mA. That gives you the general operating points. The 2P29L is filament bias, the 10Y and 46 are normal bias with DC Link bypasses at 40uF. I will make the next 10Y in filament bias. Rod's regs as usual.
I use chokes in my filament supplies. I'm a bit lazy about transformers - I use up whatever I have, which is mostly toroids which Rod disapproves of. But to my ears the chokes help. For the 2P29L I use Hammond 158T chokes. For the 10Y and 46 I use Hammond 159ZC.
If possible, try to using transformer, which have separated primary and secondary chambers.
This type transformers have minimized primary-secondary capacitance, so disturbances from the (primary) line are less bothered the secondary.
https://ce8dc832c.cloudimg.io/v7/_c...sign=452c6d3c63b2074d9a2702b3868b3ed5570236ef
I usually use Indel transformers, but any similar is appropriate.
https://www.tme.eu/hu/en/katalog/transformers-with-fastening_100531/?mapped_params=2:337;101:1445764;444:1445638;445:1445082;
The rule of thumb: use at least two-three times larger dissipation transformer than load!
p.s. sample (working!) LT PSU for 10Y/801a
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Thanks John,
I did that and included a LL2733 input choke. The p-p ripple is reduced to about 0.3 mV, see attached. Please let me know if you note any abberations in the PSUD execution.
The caps were the ones you suggested...EPCOS B41252A5229M000 at Digi-Key, $5.07 each. They are 105C, life is only 2000Hr at that temp, but increases to 20000Hr @ 71C and 50000Hr@60C...shall see what they actually run at.
Best, RC
Attachments
Hi Euro21,
Thanks for your reply! Great advice.
Trouble is that the transformers I am using are a split-bobbin design. (Separate chambers for primary and secondary.)
Hammond 185 series. Plenty of current for the 123mA 2P29L filaments.
Theoretically, these should work great, but they are somehow “leaky.”
They are, I admit, budget models.
This is why I am asking for specific makes and models. I want to be sure the next filament trafos I buy will be hum-free.
Best regards,
John
Hi Andy,
I don’t mean to be nosey, but what are the make of your toroids?
I am thinking of just buying some of the “AS” series toroids from Antek. They have an electrostatic screen between the primary and secondary windings which should reduce the leakage.
I’ve bought from Antek for many years, now. Good products on the whole, I think.
Best regards,
John
Various - no electrostatic screen. Just standard stuff off CPC, Rapid, RS etc. I put the extra cash into chokes.
I don't know if that's the "best" way to do it - I just assumed chokes would be more effective. Open to views on this.
split-bobbin design are quite good to avoid capacitive coupling primary>secondary
They should be.
For some reason the Hammond 185 series (or at least the ones I have) seem to have trouble, despite being split-bobbin.