badwhitevision
Recruit
This might go either here or in the computer hardware forum, but since a 12v adapter is commonly used for a lot of things, I am posting it here.
This might be a first, a whole dicussion for a simple 12V adapter, but I overthink things and I am thinking a lot about this one to the point that I am obsessing over it.
The requirement:
I need a 12V 5A adapter to charge a 2S Li-ion Battery Pack that acts as a UPS to run an external enclosure for a 3.5 inch HDD.
Why 5A? The start-up current of the HDD is around 2.85 A and it then idles at 0.85A with writes/reads when torture testing going up to 1.2A. Now the adapter supplied with the external enclosure is rated for 1.5A but is able to provide the start up current. This adapter is at it's max (and above it with the startup current) only with powering the drive, hence asking for a 12V 5A adapter makes sure I have a lot of headroom for the charger too.
The options:
A standard chinese black plastic adapter. 2 pin AC input and a barrel jack.
A "server" SMPS (the ones that come in a metal casing) with 3 pin AC inputs and multiple DC outputs (all of the screw type variety).
The concerns:
1. The HDD enclosure has the ground for 5V and 12V tied. This means that any noise/ripple on the 12V input is going to find it's way into the computer.
Why should I care about the noise/ripple?
Good question, and usually I don't. But in this specific instance, the computer also has a USB SDR (Software defined radio) attached. This means that such noise is going to bring up the noise floor of the entire spectrum and makes the SDR unusable.
The solutions:
1. Isolate the 5V input to the SDR via a LC choke and hope it deals with the problem.
2. Get an 12V PSU that ensures that no noise/very less noise reaches the USB input.
I am looking to solve this via number 2.
To this end, my basic understanding of electronics tells me that plastic adapters are no good here, since there is no earthing and hence any noise is directly sent to the output. (But contrary to this limited knowledge of mine, an old Pace adapter that I had actually had a low noise floor).
I would like to buy the metal ones, but they seem to be in a range of prices and the ones from Meanwell and the like seem to be ₹1000+ for a 60W PSU. (On the low end, there are ones that are ₹300)
Similarly, the black plastic adapters also are in a range of prices. I already have an old Pace 60W adapter (which is a 2 pin plastic adpater) and it was one of the better ones with a low noise floor. However, it had to be relegated to other duties, hence the need for a new one.
I know I sound very confused. But basically I am looking to buy a bang for the buck low noise/ripple 12V 60W PSU and am confused with whether I should buy an "adapter" or "Server".
Also, I am not a major in electronics/electrical/anything. This is a hobby of mine and while over the years, I have gained some little knowledge trawling the internet, I have no formal knowledge of the subject. So I might have made mistakes, called out terms wrong etc.
Calling on people with more experience to help.
@napsterquest is someone I have seen dealing with low voltage electronics, so tagging you here. Apologies if you are not the right person.
Thanks,
badwhitevision
This might be a first, a whole dicussion for a simple 12V adapter, but I overthink things and I am thinking a lot about this one to the point that I am obsessing over it.
The requirement:
I need a 12V 5A adapter to charge a 2S Li-ion Battery Pack that acts as a UPS to run an external enclosure for a 3.5 inch HDD.
Why 5A? The start-up current of the HDD is around 2.85 A and it then idles at 0.85A with writes/reads when torture testing going up to 1.2A. Now the adapter supplied with the external enclosure is rated for 1.5A but is able to provide the start up current. This adapter is at it's max (and above it with the startup current) only with powering the drive, hence asking for a 12V 5A adapter makes sure I have a lot of headroom for the charger too.
The options:
A standard chinese black plastic adapter. 2 pin AC input and a barrel jack.
A "server" SMPS (the ones that come in a metal casing) with 3 pin AC inputs and multiple DC outputs (all of the screw type variety).
The concerns:
1. The HDD enclosure has the ground for 5V and 12V tied. This means that any noise/ripple on the 12V input is going to find it's way into the computer.
Why should I care about the noise/ripple?
Good question, and usually I don't. But in this specific instance, the computer also has a USB SDR (Software defined radio) attached. This means that such noise is going to bring up the noise floor of the entire spectrum and makes the SDR unusable.
The solutions:
1. Isolate the 5V input to the SDR via a LC choke and hope it deals with the problem.
2. Get an 12V PSU that ensures that no noise/very less noise reaches the USB input.
I am looking to solve this via number 2.
To this end, my basic understanding of electronics tells me that plastic adapters are no good here, since there is no earthing and hence any noise is directly sent to the output. (But contrary to this limited knowledge of mine, an old Pace adapter that I had actually had a low noise floor).
I would like to buy the metal ones, but they seem to be in a range of prices and the ones from Meanwell and the like seem to be ₹1000+ for a 60W PSU. (On the low end, there are ones that are ₹300)
Similarly, the black plastic adapters also are in a range of prices. I already have an old Pace 60W adapter (which is a 2 pin plastic adpater) and it was one of the better ones with a low noise floor. However, it had to be relegated to other duties, hence the need for a new one.
I know I sound very confused. But basically I am looking to buy a bang for the buck low noise/ripple 12V 60W PSU and am confused with whether I should buy an "adapter" or "Server".
Also, I am not a major in electronics/electrical/anything. This is a hobby of mine and while over the years, I have gained some little knowledge trawling the internet, I have no formal knowledge of the subject. So I might have made mistakes, called out terms wrong etc.
Calling on people with more experience to help.
@napsterquest is someone I have seen dealing with low voltage electronics, so tagging you here. Apologies if you are not the right person.
Thanks,
badwhitevision
