REDUCING AMPERAGE for delicate electronics

Re: REDUCING AMPERAGE for delicate electronics

Wayne from NS Cana wrote: »

Just a note, many "wall warts" have a substantially higher "no load/low load" output voltage than claimed. It's not uncommon to see a 9 volt unit putting out 12, or a 12 volt unit delivering 16, or 18. I was rather shocked when I first saw that, but soon learned it was quite common with many manufacturers.

An interesting little tangent. There are other variables, too.
I only recently grasped what Wayne was saying. I recently read that wall adapters put out a specific voltage at a specific load (amperage). So with no load, they should put out more voltage than specified. At a high load, less voltage. However, it is also true that some special adapters are "regulated" to put out the same voltage, more or less, at different loads.
But I discovered that INPUT matters a lot, too:
I tested a 12v, 500mA adapter at home off a cheap inverter that puts out 111V AC, and got 11.12V DC output with no load. The same adapter plugged into a grid wall socket putting out 123V AC produced 17.67V DC!

Re: REDUCING AMPERAGE for delicate electronics

Wayne from NS Cana wrote: »

Yes, definitely control the VOLTAGE, and the current will take care of itself. You just have to make sure enough current is available for the biggest demand that the load will need and fuse it properly, in case there might be shorts.
Cheers
Wayne

Yeah, well, must be something else wrong, then.
I did by the pricey DC/DC converter, PST-DC/2812-8 by PowerStream,
http://www.powerstream.com/dc-buck-boost.htm, and it does put out 12.16V any time I check, BUT it has not helped the problems at all. A total waste of money, as far as I can see. Here's an email thread I had with the seller about it: (and of course the sellers of the items I was trying to run claim that something's wrong with my power supply...)


(quote) This can't be explained by the DC converter. The main thing that blows capacitors is high voltage,
the other thing is putting a lot of AC current through them. Neither can be explained by the
house wiring or the DC converter.

We sell a lot of these converters to people that stabilize voltage in cars and busses, very noisy
conditions and we haven't had any complaints.



Dexter Ator wrote:

> That sounds plausible...
> I should say that the adapter behaved similarly without the buck booster when I had somewhat lower voltage in the walls. In fact, I had them replace a couple under warranty as they failed. This was the main reason I bought the buck booster.
>
> But I have also had similar problems with a mono amp designed for up to 18V:
> http://www.designnotes.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=K4001&Category_Code=auha
> Which blew its central capacitor directly on my system before the buck booster, probably at 13-14V. Then again, shortly after I plugged in the repaired unit with the buck booster, it blew its central capacitor. We're talking volcanic eruptions.
> These amps don't blow on a wall wart plugged into 120AC.
>
> So the buck booster does not seem to help at all with the problems that were obvious, and presumably doesn't help on any less-obvious problems that might or might not be there with other devices. I was expecting it would normalize my juice so things would run right. But I see no benefit.
>
> Mark W Lund, PhD wrote:
>
>> Wow this is a real stumper. Is it the laptop adapter that is getting hot?
>>
>> The only thing that I can think of is that sometimes when you have one switchmode power supply feeding
>> another they can drive each other crazy. For example the second converter is trying to draw constant power,
>> so it will increase its amp draw if the input voltage falls in order to keep at a constant wattage. But the
>> first one is trying to regulate to a constant voltage. So if the output voltage falls (say a disk drive kicks in) the
>> first converter will increase the voltage at the same time the second converter is trying to increase its input current.
>> This can set up oscillations, even chaotic oscillations.
>> This rarely happens when the dc converters are properly designed, but since you can't test every possible combination
>> it does happen.
>>
>> Best regards
>> mark
>>
>> Dexter Ator wrote:
>>
>>> Maybe you can help me. I bought a PST-DC/2812-8 several months ago because I have a couple thiings that won't run on my 12V home solar system. I thought this was due to fluctuating and excess voltage.
>>> But the items don't work much better through the PST-DC/2812-8. Although they run fine on a 12V wall adapter plugged into the grid, or a 12V jump-start pack.
>>>
>>> The PST-DC/2812-8 always says about 12.16V when I check it, which should be great.
>>>
>>> E.g. my auto laptop adapter (maybe I should have bought one from you instead of the PST-DC/2812-8) works dandy on my jump-start pack for hours on end, but on the PST-DC/2812-8 gets too warm and malfunctions after a 1/2 hour.
>>>
>>> __________ NOD32 2696 (20071130) Information __________
>>>
>>> This message was checked by NOD32 antivirus system.
>>> http://www.eset.com
>>>
>>>
>>>
>>
>
> __________ NOD32 2696 (20071130) Information __________
>
> This message was checked by NOD32 antivirus system.
> http://www.eset.com
>
>
>

--

---

Mark W. Lund, PhD ** Battery Chargers
CEO ** Bulk Cells and Custom Battery Packs
PowerStream Technology ** Custom Power Supplies
140 S. Mountainway Drive ** DC/DC Converters
Orem Utah 84058 ** Custom UPS
(01)801-764-9060 ** Battery backup http://www.PowerStream.com ** Engineering, manufacturing, consulting

Re: REDUCING AMPERAGE for delicate electronics

Yeah, this is a strange situation. There's got to be more going on than we know about. All these capacitors blowing up, it makes no sense if the voltage is anywhere near where it should be, not reverse polarity, nor AC and not loaded with ripple. I spent my working life in hands on electronics, design and repair, so I know more about this issue than many others would.
Heck, when I was a kid, I used to solder 12 VDC caps across the 120 VAC input to radios, then give them so some unsuspecting person to turn on. Haha. I was a bad little bugger. To be making these capacitors blow up, they either have to be supplied with huge overvoltage, reverse polarity, AC, or a combination! Any of those situations would, in short order, destroy the rest of the electronics as well. It's got to be one of three things, there's more to the story than we're being told, or we're being given wrong info, or someone is pulling legs. I don't mean this post to sound sharp or crabby, but with the info we're being given, we're just spinning our wheels.
Wayne

Re: REDUCING AMPERAGE for delicate electronics

Ha, yeah, for sure the title to the thread was misguided.
But there is some kind of weird problem.
The voltage in the walls is way too high. It's supposed to float at 13.4v or something, but the wall voltage when the TS-45 is in float mode is 15.85.

If I bypass all the house wiring, disconnect it all from the unit, and run leads directly from the batteries to the TS-45, and measure the voltage in-line at the controller, it is around the proper float range.

Hence, probably some weird wiring fault is causing the TS-45 to misbehave and allow more voltage in than it is set for.

So, when the weather clears up I need to either find the problem, or route all new wiring somehow.