I have also used this one. I ran a small mono push pull amp ( pair of 6K6's ) with it and it seemed ok. IIRC, I was pulling about 50 ma at 250 volts from it, and it didn't overheat. I didn't hear any audible artifacts, but I didn't measure anything.
Mine is real sensitive to the quality of DC input, in a way that I haven't figured out. Using an ordinary bridge rectifier, some transformers would work perfectly fine, and others, that should have, just wouldn't.
I ordered a couple more to see if they were all like that, or mine was just weird, but I haven't tested the others. They were about $6 USD when I bought mine.
Win W5JAG
Same here!
Just could not get the hum out. And the heater circuit is hum free.
Tried this dc-dc converter just to see and got blown away.
Ordered one more not to overload the one.
I am also still a bit reserved to this ebay stuff.
I have not done any measurement. Not quite sure what to look for.
Just could not get the hum out. And the heater circuit is hum free.
Tried this dc-dc converter just to see and got blown away.
Ordered one more not to overload the one.
I am also still a bit reserved to this ebay stuff.
I have not done any measurement. Not quite sure what to look for.
I use one of these modules for an Aikido 6N1P/6N6P headphone amp (280V 70ma) and it's not bad but it will oscillate requiring me to set it at 350V and use a large dropping resistor.
I've also used the dual output board also mentioned here. Good for a CCDA phono stage.
My favourite ones are NOT adjustable: DC-AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer
The listing title is wrong, it's actually DC-DC and it works great.
I also have one of these which I will try.
MINI DC-AC Inverter 12V to 18V220V/380V 500W Boost Step UP Power Module New Hot
Cheers
I've also used the dual output board also mentioned here. Good for a CCDA phono stage.
My favourite ones are NOT adjustable: DC-AC Converter 12V to 110V 200V 220V 280V 150W Inverter Boost Board Transformer
The listing title is wrong, it's actually DC-DC and it works great.
I also have one of these which I will try.
MINI DC-AC Inverter 12V to 18V220V/380V 500W Boost Step UP Power Module New Hot
Cheers
Yes, i have noticed that it will go on/off in a nasty way if direct connected
to a large cap. But a series resistor of a few 100 ohm will keep it stable,
it's still a powersupply with very little "sag".
( i am refering to the DC10-32V to DC +-45-390Vsupply )
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I want to clarify that the module I have used is the DC 10-32V to DC +- 45-390 VDC also being talked about, and not the module that the OP posted up.
In addition to the transformer weirdness I experienced, I also observed the propensity to high frequency oscillation that petertub notes. Seems like I used 130 ohms to 180 ohms in series, with a pretty big cap, on the output, to kill it.
Despite the quirks, I thought enough of it to buy a couple more since they were cheap, but they may or may not be plug and play, depending on the use they are put. Some experimenting will probably be necessary.
OTOH, I have used some of the low voltage DC-DC converters labeled "Tusotek" as DC filament supplies for DHT's, and they are absolutely terrific in that application, and very inexpensive.
Win W5JAG
In addition to the transformer weirdness I experienced, I also observed the propensity to high frequency oscillation that petertub notes. Seems like I used 130 ohms to 180 ohms in series, with a pretty big cap, on the output, to kill it.
Despite the quirks, I thought enough of it to buy a couple more since they were cheap, but they may or may not be plug and play, depending on the use they are put. Some experimenting will probably be necessary.
OTOH, I have used some of the low voltage DC-DC converters labeled "Tusotek" as DC filament supplies for DHT's, and they are absolutely terrific in that application, and very inexpensive.
Win W5JAG
Yes that one will do it, too. I used a 2k dropper to get rid of it, but only a 22u to 47u cap. More I find unnecessary, considering I'm using that module in a CCDA phono stage.
Edit: The oscillation seems to be around 300Hz, which is weird considering the switching frequency is 75kHz.
Cheers.
I have found the "unstable" behaviour easily solved by a small series resistance. Even with that resistor ( < 500ohm) the powersupply is still more constant and ripplefree then most conventional unregulated transformer supplies. The unstable effect seems to be a too sensitive voltage regulation. Whatever the cause i find these devices very interesting,
300 hz could be caused by a voltage ripple of the incomming DC voltage being impressed on the switcher driver. overall sag isn't that important to git rid of in the tube amp. Ideally you want the sagging to be observed between the output primary and output plate in a hi fi setup. In a guitar amp you want more sag because of the compression effect it imposes on the signal.
75Khz is really low when it comes to hi-fi switching. I can see it becoming problematic in some tubes because excess noise in this region can effect the total gain of the tube. Its bearable for the tube itself in regards to recovery (because they have a poor off timing compared to semiconductors) and they are more of a voltage potential demand device than a high current demand device.
One thing I will point out, the standard switching frequency is 200Khz in modern audio amps. This was chosen because its switching frequency can recover the current 10 times faster than the nominal current demand over the total desired bandwidth (20Khz).
75Khz would be what you would typically see in a CRT television, crt projector, and CRT computer monitors.
I also want to point out that these power supplies should be shielded in some way, and its DC power filtered properly (with small pF caps stripping the high frequency signals on the DC voltage)
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I agree with You, i melted one of these at even lower power.
The 45-390V however will keep up( they will get hot but won't fail)
Does that mean you could only get 40W when using max input voltage? or that transformer temp was measured as being too high for the ferrite? Or was your comment only pertinent for say 12Vdc input?
In theory you can get more power out with a higher input voltage, but the weakness seems to be the secondary of the transformer. Therefore I wouldn't expect more than 60-70ma output current almost regardless of the i/o voltages. I've never used one with more than 12V as I use an SMPS to drive it. If you design the circuit conservatively these modules give great results, especially the one I posted previously with jumpers to set output voltage. I'm using one of those in a preamp with 16 tubes in it, about 200ma at 280V. It gets hot (mounted inside the chassis, heatsinks reach 90+C but it works fine.
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If the insulation breaks down it will blow it's fuse (or in the case of the one I had that melted down it will cause the protection on the power supply feeding it to trip). It's rated to 450V because that's the rating of the filter cap. Still 350V is easy for it. Just keep the thing under 40W and it's fine.
Just because it isn't expensive doesn't mean it's junk. Granted it's a turd compared to something similar from Digikey but it's also 1/10th of the money. Great for a line amp, HP amp, phono stage. Don't use these little ones for power stages though.
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