Hello all,
So I have had two, two channel power supplies I’ve been using for awhile. A Siglent with two 32V 3.2A channels and a third with 5/3.3V and the other is a two channel Sorensen 75V 2A. I recently picked up a couple Lambda supplies and from what I read they’re top tier. Each supply is 100V 15A.
The manual mentions twisting the output wires together. I’ve never seen anybody twist the outputs of their power supply together. The output of the power supply will have a couple of 18 inch wires coming out of it and they will terminate to a pair of binding posts. Does anyone twist the output wires to theirs? I would think that with only 18 inches it wouldn’t seem beneficial, maybe it means for longer runs?
These power supplies have hook ups for sense wires. Neither of my other power supplies do, how do y’all feel about sense wires? Needed? Would the average hobbyist find them useful?
Lastly, there is an area on the back to hook up the chassis ground of the power supply. I can hook the chassis of the two power supplies together, and then run a hook up by the finding posts. Though I’m thinking I would do without since every single piece of audio equipment on my bench is on an isolation transformer, if I hooked up the ground, it would totally negate the isolation transformer. The section here where it mentions floating the output above ground and limiting it to 100 V for this model, is that in reference to only if I choose to hook up the power supply ground to my device under test ground?
Thank you,
Dan
So I have had two, two channel power supplies I’ve been using for awhile. A Siglent with two 32V 3.2A channels and a third with 5/3.3V and the other is a two channel Sorensen 75V 2A. I recently picked up a couple Lambda supplies and from what I read they’re top tier. Each supply is 100V 15A.
The manual mentions twisting the output wires together. I’ve never seen anybody twist the outputs of their power supply together. The output of the power supply will have a couple of 18 inch wires coming out of it and they will terminate to a pair of binding posts. Does anyone twist the output wires to theirs? I would think that with only 18 inches it wouldn’t seem beneficial, maybe it means for longer runs?
These power supplies have hook ups for sense wires. Neither of my other power supplies do, how do y’all feel about sense wires? Needed? Would the average hobbyist find them useful?
Lastly, there is an area on the back to hook up the chassis ground of the power supply. I can hook the chassis of the two power supplies together, and then run a hook up by the finding posts. Though I’m thinking I would do without since every single piece of audio equipment on my bench is on an isolation transformer, if I hooked up the ground, it would totally negate the isolation transformer. The section here where it mentions floating the output above ground and limiting it to 100 V for this model, is that in reference to only if I choose to hook up the power supply ground to my device under test ground?
Thank you,
Dan
You have 2 1500W lambda power supplies on your bench? Is it reinforced steel? What are you planning to power from those? The Lambda linear power supplies are really good. Very low noise and pretty much bulletproof. And heavy with lots of transformer iron.
If they are the newer switching supplies they seem pretty capable but you need 40A service to get the full power (21A ea at 120V) Thats a whole house air conditioner level of power. They are potentially quite lethal so be very careful.
The 100V limit is because it doesnt have adequate internal insulation for much higher voltages.
At 15A sense lines are essential. You will get significant drop over the supply wires.
I'm not clear from the notes but it seems there is a chassis ground that is isolated from the supplies but they want to make sure you do not get or send noise from the supply. Tieing the chassis all together is usually good practice both for noise and for safety. Driving a big digital or switching load (e.g. motor controller) there will be a lot of current modulation that will radiate magnetically from the wires. Thats why you want to twist them, the smaller the area between the wires the lower the radiation.
If they are the newer switching supplies they seem pretty capable but you need 40A service to get the full power (21A ea at 120V) Thats a whole house air conditioner level of power. They are potentially quite lethal so be very careful.
The 100V limit is because it doesnt have adequate internal insulation for much higher voltages.
At 15A sense lines are essential. You will get significant drop over the supply wires.
I'm not clear from the notes but it seems there is a chassis ground that is isolated from the supplies but they want to make sure you do not get or send noise from the supply. Tieing the chassis all together is usually good practice both for noise and for safety. Driving a big digital or switching load (e.g. motor controller) there will be a lot of current modulation that will radiate magnetically from the wires. Thats why you want to twist them, the smaller the area between the wires the lower the radiation.
I actually currently have four. The first one I picked up was a 50V 30A and was really impressed with the build quality. I just only wish that they had outputs on the front, but these are meant for mounting in a rack. So I just ran a wire about the same length as the power supply under them to a set of binding posts at the front side. I then picked up a pair of 100V 15A so that I could run bipolar voltages in pretty much power any amplifier imaginable just feeding into its filter cans. I also picked up a single 300V 5A supply, I may grab another one, but don’t know what I would need bipolar 300V for, although I have a couple of amplifiers that run on 120V rails, so I know they’re out there. For testing purposes, though I’m sure +/- 100V would work well enough.
They most certainly are not linear lol, in that case, I would most definitely need reinforced steel. I like them because they’re nice and thin and I can stack them. I do understand to power all of these. I would need a crazy amount of current capability in my lab, but who’s going to run all these power supplies at their limits at the same time? Nobody, nobody is lol. I do have two 20 amp supplies in the lab though. They make the same power supplies, but at half the power (750W) I would’ve been perfectly happy with those, but I got these at such great prices it would have been stupid not to pick them up.
My wiring is basically like the lower image here.
I have the plus and minus going out and to a couple of finding posts and then I hook up whatever I want from those bindings posts. I originally used these.
But I am swapping over to these as if I have a potential 200 V across them when running bipolar I don’t want something to be knocked over and hit them, would like some type of protection so I figured the insulated were a better way to go.
So, after reading, I think I will wire in the sense wire to the binding posts. Although it’s only 18 inches from the output and I’m using oversized wire, 10 gauge. It would be nice to have the voltage be as accurate as possible, though.
I’ll make sure to keep access to the ground, but I don’t see myself ever using it. I don’t use it on my other power supplies either because I’m always wanting to keep the device I’m testing isolated from the main ground. I will attempt to twist the wires, although on the 30 amp rated power supply it’s using an 18 inch length of six gauge wiring, again oversize and don’t think I could twist that one effectively.
Dan
Since you explained the importance of twisting the wires to me, I’m gonna swap over to this wire. Each power supply has two hook ups for the positive and two hook ups for the negative, so I can double up on this 14 gauge wire which would effectively be 11 gauge, still more than sufficient for 15 amps.
I will do the same with something a bit smaller like 20 gauge for the sense wires.
Dan
I will do the same with something a bit smaller like 20 gauge for the sense wires.
Dan
Another question I have, the dip switches. The previous owner has them in positions that I wouldn’t think would be right for my use.
Like which one, in the position it’s in the output voltage would be programmed by outside source and not the front panel. Though when I measure the output voltage is exactly what the front panel says so I’m wondering if pin nine being in the down position completely eliminates what those other switches do. It doesn’t say specifically, but I’m guessing the switches is the rear panel in control???
Got the remote sense wires in as well.
Dan
Like which one, in the position it’s in the output voltage would be programmed by outside source and not the front panel. Though when I measure the output voltage is exactly what the front panel says so I’m wondering if pin nine being in the down position completely eliminates what those other switches do. It doesn’t say specifically, but I’m guessing the switches is the rear panel in control???
Got the remote sense wires in as well.
Dan
Soldered pure copper terminals. Two wires each for the positive and negative side of the supply and a positive and negative for the remote sensing.
Sinched them down and all is good. I haven’t tested them up to the full voltage and current, I have at full voltage, but not the full 15A of current.
Dan
Sinched them down and all is good. I haven’t tested them up to the full voltage and current, I have at full voltage, but not the full 15A of current.
Dan
Those Lambda supplies are fantastic, I've got a number of them at work and they're as good as it gets. I believe they are rebadged HP/Agilent supplies, but it's also possible that Agilent rebranded a Lambda supply.
As for twisting the leads, that's just to minimize loop area, which isn't a bad idea if you're running amplifiers off them (which these are perfect for). Sense leads are useful, but quite honestly optional for most things done on a lab bench. It's a lot more useful if these are running very sensitive equipment a significant distance away.
As for twisting the leads, that's just to minimize loop area, which isn't a bad idea if you're running amplifiers off them (which these are perfect for). Sense leads are useful, but quite honestly optional for most things done on a lab bench. It's a lot more useful if these are running very sensitive equipment a significant distance away.
I really appreciate the response. I was actually going to post another thread, but I’m thinking probably not now. I may if I don’t get a response here, but I was curious what would be considered acceptable as far as noise on the supply. Obviously people consider linear supplies to be superior, but to get a linear supply that could provide as much as these, they would be huge and heavy. I would imagine that these are pretty much as low noises you could get for switching supplies. I looked at the specs and they look to be 8 mV rms ripple spec at rated output (5 Hz - 1 MHz) and then something like 60 mV peak to peak noise (<20 MHz). I’m guessing that for powering older amplifiers and such that won’t be a problem at all, but I’m curious when noise like that would be create an issue. I would figure that cheaper Chinese power supplies have much more noise than what these would have.
I was under the impression that lambda actually made these for HP and Agilent. Just finished getting the fourth one installed this weekend, it’s the 300V 5A model, would like to find another one for bipolar 300V, but not sure I’d ever need that.
Dan
Quite honestly, most solid state amplifiers aren't going to care about 50 mV of switching ripple. If the HF noise is bothering you (and these things really aren't bad in that regard), then put a couple of ferrite cores on the output lead to suppress the switching transients.
I like to have a really good quiet linear supply for when I'm playing with very noise sensitive stuff: old-school mic preamps, high-gain transimpedance amps for photodiodes, etc. I've built a few, and I've got a few HP ones that are good as well.
I like to have a really good quiet linear supply for when I'm playing with very noise sensitive stuff: old-school mic preamps, high-gain transimpedance amps for photodiodes, etc. I've built a few, and I've got a few HP ones that are good as well.