I'm looking for a recommendation for a 12vdc linear regulated desktop wart able to produce about 10-watts.
I'd like a DESKTOP wart if possible, which is sort of a wall wart but has a cord for connection to the receptacle, instead of the blades being built into the wart.
I'd be happy with used. Very difficult to tell if what I'm seeing is regulated or not (typically not I suppose). I figured maybe someone here has experience with a brand of something that ticks the marks.
Jameco has a wall-wart version:
DFU120150/G9760: Jameco Reliapro : 18 Watt 12 VDC 1.5 Amp Regulated Linear Wall Adapter : Power Supplies & Wall Adapters
So I guess that is an option, if I cannot find something else.
I'd like a DESKTOP wart if possible, which is sort of a wall wart but has a cord for connection to the receptacle, instead of the blades being built into the wart.
I'd be happy with used. Very difficult to tell if what I'm seeing is regulated or not (typically not I suppose). I figured maybe someone here has experience with a brand of something that ticks the marks.
Jameco has a wall-wart version:
DFU120150/G9760: Jameco Reliapro : 18 Watt 12 VDC 1.5 Amp Regulated Linear Wall Adapter : Power Supplies & Wall Adapters
So I guess that is an option, if I cannot find something else.
The vendor writes "No agency approvals"
In other words he offers illegal stuff.
A transformer power supply of that kind does not meet requirements of ECO directive because of its poor efficiency.
Such equipment is illegal nowadays and may be destroyed by the customs.
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If only I could find a version that had a cord instead of plugging directly into a receptacle.
Anyone want to take a guess at this?
12VDC 1Amp Power Supply + plug adapter kit complete Tested IOB Archer #273-1653A | eBay
25 watt input and 12 watt output would sort of imply linear, not switching, right? Not efficient enough for switching?
Likely regulated? And made in Taiwan, with Radio Shack label, probably pretty decent?
Also here:
Sonance OPTILINK PS2 Power Supply 12VDC 1A PN# 91356 | eBay
40w input and 14-15 watt output, that seems even less efficient, and it SAYS regulated.
Any thoughts?
12VDC 1Amp Power Supply + plug adapter kit complete Tested IOB Archer #273-1653A | eBay
25 watt input and 12 watt output would sort of imply linear, not switching, right? Not efficient enough for switching?
Likely regulated? And made in Taiwan, with Radio Shack label, probably pretty decent?
Also here:
Sonance OPTILINK PS2 Power Supply 12VDC 1A PN# 91356 | eBay
40w input and 14-15 watt output, that seems even less efficient, and it SAYS regulated.
Any thoughts?
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Because I'm powering an old Technics turntable motor controller (SL-6) and switching power supplies present noise issues.
And I'm no expert, but both of those looked largish and I suspected they'd have a transformer, so linear? Or does a transformer not mean linear?
I have 12vdc 1.5a switching warts and they're very small and light.
Feel free to educate me.
It depends on the age. They will certainly be lighter than linear (smaller transformer), but I see no reason why you couldn't use an SMPS and filter the output of that instead. I use SMPS to power RIAA tube phono amplifiers and there is no noise issue. If it needs to be linear, why not build one?
A 12V transformer, a couple of capacitors, and a 7812K should do the job... Still, filtering the SMPS seems easier.
A 12V transformer, a couple of capacitors, and a 7812K should do the job... Still, filtering the SMPS seems easier.
These are relatively quiet, too: AC110 220V Power Supply Adapter Transformer LED Strip 2A 3A 5A 8A DC 5V 12V 24V | eBay
What depends on the age?
I thought older/larger/heavier meant there was a transformer, which means it is linear?
Is that not the case?
In other words, switching supplies wouldn't employ a large/heavy transformer?
Use an extension cord then.
There are some rough rules of thumb for small AC adapters, under 15 Watts or so.
1. If the power input is 120V 60 Hz only, it is probably linear. Switchers these days cover 100V - 240V and 50 - 60 Hz.
2. Linears are large, heavy and inefficient compared to switchers which should be 70% efficient or better.
3. If a linear AC adapter is not specified as regulated, it probably isn't.
Both adapters you found appear to be linear but the 273-1653A is probably not regulated.
It isn't clear why a switcher is not suitable to run a turntable motor. Not all of them are very noisy - have you tried one and found it to be unusable?
Thank you (and everyone) for your help.
When using a small switching supply (12vdc, 1.5a), I get some audible noise picked-up in the signal. Sounds sort of like 7k or 10k and is faint but not faint enough. As I adjust the gain up on my phono stage, the noise is amplified with it. When I unplug the power supply, the noise instantly goes away.
So I picked up a couple of 12vdc linear wall warts (each 12vdc 1a) for $2 each at a thrift store. I'm pretty sure these are unregulated, but I don't know how to tell. Googling part #'s didn't help. One is a Teac, the other a Cambridge Soundworks. I don't get the noise with either of these. But sometimes, the table won't start with these unless I give it a little nudge. Once started, it runs fine and is about as torque-y as with the switched supply.
My theory is that the lack of regulation is causing a problem with the linear supplies. I don't think the problem is the smaller 1a (versus 1.5a) rating, as the running table is pulling 2w (according to my Kill-A-Watt meter). Slowing the table with my thumb causes the power consumption to increase to as high as about 6w. I suppose I could be right on the line, that when the platter isn't moving that the power supply is just shy of what is needed to start it. BTW, the specs for the Technics SL-6 turntable indicate a power consumption of 11-watts, but there are some boards and an additional motor or two (for tonearm control) that I'm not using.
The noise might be a problem with my cheap phono stage. OTOH, I figured the best way forward would be to simply find an inexpensive linear regulated supply.
FWIW, this motor is a magnetically driven servo-type thing, where there are permanent magnets (a ring) mounted to the bottom of the platter and a PCB that fires some electro magnets correctly. I'm actually very surprised that when the linear power supplies don't start it (about one out of four or five times), that nudging the platter gets it going.
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