Found these DC/DC converters for B+:
www.revintage.se/RecomDCDC.pdf
Recom have modules for 12V to up to 350V that also can be stacked.
Just an idea to have only a 12V transformer to get 12,6V DC for the preamp heaters and from there via the converters to anodevoltage.
Anyone who have tried?
www.revintage.se/RecomDCDC.pdf
Recom have modules for 12V to up to 350V that also can be stacked.
Just an idea to have only a 12V transformer to get 12,6V DC for the preamp heaters and from there via the converters to anodevoltage.
Anyone who have tried?
For a start, you can't use a 12.6 volt transformer. Transformers only utilize AC. To get the DC input required, you'll need a rectifier and filter circuit. Another consideration is that these switchers run at 200 kHz according to the spec. sheet. That could produce switching noise in whatever you want to use them in. Third, the output is only 50 ma. If you stack them, only the voltage adds, the output current remains at 50 ma. If you can overcome these limitations, there's no reason they won't work.
sherlock
sherlock
r221b said:
I asked if someone had tried them!
All you say is obvious: Of course you have to have a transformer to rectify from AC to DC! How should you otherwise do?
As I said preamp, 50mA should not be a problem.
And I wanted to know if someone had tested this IRL as swithcing noise probably is the issue that could be a problem.
So back to the question I wanted answer for: Have you or someone else tried them or any similar device.
Just found a test in Stereophile where Nagra uses this solution in their tube preamp so it must work! Will take a deeper look!
Just trying to help.... I haven't a clue as to your technical knowledge or lack thereof. From what I've seen on this forum, there are people that know virtually nothing about electronics all the way up to electrical engineers. What's "obvious" to you probably isn't to a lot of others. Since I took the time to reply, a simple "thanks" might have been in order. I hope you get your answers.
sherlock
sherlock
Sherlock: Thank you for taking you time to answer. Sorry, did not mean to insult you 
.
When I did not find the answers at Google, I asked here. Thought the knowledge level was higher. If you are still wondering about my level pls check my site www.revintage.se.
. When I did not find the answers at Google, I asked here. Thought the knowledge level was higher. If you are still wondering about my level pls check my site www.revintage.se.
I looked up these converters since they would fit right in to an upcomming project (a battery powered tube guitar preamp). Unfortunately there is only one supplier in the US, and they only stock a few parts. No HV stuff, only 5 and 12 volt parts.
I have been experimenting with SMPS's and DC to DC converters for vacuum tube uses. The 200 KHz switching frequency is not a problem. The 30 to 50KHz converters can be a problem. As I am trying to mount the preamp inside the guitar, I have found that some designs can play havoc with a guitar pickup even at a distance of over 1 foot. Toroidal inductors are your friend. Unshielded ferrite bobbins are not.
I have been experimenting with SMPS's and DC to DC converters for vacuum tube uses. The 200 KHz switching frequency is not a problem. The 30 to 50KHz converters can be a problem. As I am trying to mount the preamp inside the guitar, I have found that some designs can play havoc with a guitar pickup even at a distance of over 1 foot. Toroidal inductors are your friend. Unshielded ferrite bobbins are not.
tubelab.com said:
Hi Guitar-buddy,
Can send you one when I get the R12-150As I will order. If you want a smaller one I can include it in the same order.
(About guitar-buddies: Check my bandsite: www.myspace.com/eflatjumptessandersson and also see a glimpse of my "reVintage Pro" guitar amp in between Tess and me)
Attachments
This is not always true. If the SMPS's are simple unregulated converters, yes you can generally parallel them. If the power supplies have control loops, they can misbehave. No two power supplies will put out exactly the same voltage. When parallelled the one with the higher voltage output will supply more than its share of current. Eventually it will fold back or shutdown transfering its load to the other one. Sometimes this will work but one supply may be operating in current limiting all of the time. I have seen wierd oscillations occur, and on one occasion it resulted in the violent death of both power supplies.
These converters are "stackable to generate voltages up to 420 volts". If placing converters in series, they must be "isolated converters" and the total voltage should be far less than the "isolation rating" of the converters being used. If one converter in the series string shuts down it will see a reverse voltage across its output. In some cases this will cause the output capacitor to fail (often violently). Place a reversed bias diode across the output of each converter to prevent this.
KimBOlesen said:
Hi Kim,
Recom do not recommend parallelling, so unfortunately, this is no good solution. If you download their full catalogue there is a chapter with useful technical info at the end of it.
Refering to Recoms paper serial stacking is OK if you let the lower go full out and have the upper adjustable.
Hi
@Tubelab:
I have to disagree, controlled SMPS do work in parallel . My daily work is repairing and testing SMPS so i know what i'm talking about! typical paralleled 500W smps with controlled 48Volt output and shutdown at 10,5A each! First psu will source until it's output reach max and the Vout start to drop, then second psu starts to deliver and keeps the first from entering a fold back shutdown. Offcourse there can be some smps there is impossible to parallel, but most will work.
Best regards
Kim Olesen
@Tubelab:
I have to disagree, controlled SMPS do work in parallel . My daily work is repairing and testing SMPS so i know what i'm talking about! typical paralleled 500W smps with controlled 48Volt output and shutdown at 10,5A each! First psu will source until it's output reach max and the Vout start to drop, then second psu starts to deliver and keeps the first from entering a fold back shutdown. Offcourse there can be some smps there is impossible to parallel, but most will work.Best regards
Kim Olesen
Hi
@Revintage: just found and read the application notes, they don't recommend parrallel, because off load sharing problems. Think this is because smps is missing the sense pin's and/or bad voltage regulation.
Noise can be a problem. I have seen this type of smps from many manufactures, and in different output and pin style, and some with so much noise at the output that they where useless in A/D conversion and analog electronics. You simply have to try them to see if they will work or make your own.
@Revintage: just found and read the application notes, they don't recommend parrallel, because off load sharing problems. Think this is because smps is missing the sense pin's and/or bad voltage regulation.
Noise can be a problem. I have seen this type of smps from many manufactures, and in different output and pin style, and some with so much noise at the output that they where useless in A/D conversion and analog electronics. You simply have to try them to see if they will work or make your own.
I have seen a few data sheets for DC - DC converters that say parallel connection is not recommended. The Recoms are of this variety.
I am sure that there are plenty of SMPS's that do work well in a parallel connection. There are many designs that are intended for operation in parallel. I am just bringing up the point that the average SMPS found in a surplus catalog may not work very well in parallel.
I bought a box full of 12 volt 2 amp SMPS's at a hamfest a few years ago. They work fine individually, but go bonkers if connected in parallel and used to feed tube heaters. This is a hard load for some SMPS's due to the low cold resistance. I fried two of the power supplies trying to get them to work in parallel.
<tubelab got a good point. SMPS aren't so hardy as one makes them out to be...compared to a simple tube rect and cap/choke. Whatever one does with smps it's a dogs day when charging up large hv caps and smps often fiss out doing so. An smps needs to be properly designed for tube apps and what's more if many smps are in series don't (for hxx sake) accidently short circuit them, as they will all fail one after an other.
For heater applications the situation is more favourable. I often tweaked the 431 constant current feedback cum opto drive to get 6.3V without any bother.
richj
For heater applications the situation is more favourable. I often tweaked the 431 constant current feedback cum opto drive to get 6.3V without any bother.
richj
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.