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[CAS] 開心大發現:小米的20000mAh尿袋

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 樓主| 發表於 2018-6-14 10:48:29 | 顯示全部樓層
clplarry 發表於 2018-6-14 10:10
The shop DIYINHK which I think is run by the Hong Kong people in the place out of Hong Kong. Why i ...

May be he thinks HKgers are troublesome. I don't know.
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 樓主| 發表於 2018-6-14 11:51:58 | 顯示全部樓層
clplarry 發表於 2018-6-14 10:10
The shop DIYINHK which I think is run by the Hong Kong people in the place out of Hong Kong. Why i ...

The shop owner should be in HK as the parcel I received was a registered mail from HK Post.
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發表於 2018-6-14 11:55:41 | 顯示全部樓層
如果 1A 夠用就幫襯佢好過:

https://www.ebay.com/itm/LT3045-A-Ultralow-noise-0-8-Vrms-LDO-linear-regulator-0V-15V-1A-Fixed-out-/253378132579
http://www.ldovr.com/product-p/lt3045-a.htm

3A 同埋 5A 都有:

https://www.mpaudio.net/products

淘寶淨係得 0.5A:

https://item.taobao.com/item.htm?id=529586432965
https://item.taobao.com/item.htm?id=565126246341

有人唔想做土炮生意都吹佢唔脹,真係好想買就試試上去 diyaudio.com 搵佢傾傾:

http://www.diyaudio.com/forums/members/diyinhk.html
http://www.hiendy.com/hififorum/forum.php?mod=viewthread&tid=77045&page=1#pid2054629
From diyinhk.com, but the web site had blocked the HK IPs. You may contact him from diyaudio.com.
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 樓主| 發表於 2018-6-14 12:22:23 | 顯示全部樓層
Thanks for the links. So, interested users could try other sources.
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發表於 2018-6-15 07:59:08 | 顯示全部樓層
CKL 發表於 2018-6-14 12:22
Thanks for the links. So, interested users could try other sources.

Hi Brother CKL
According to the board in the picture you attached for the LT-3045 (4 pieces) from DIYINHK, it is a dual rail designed one. In other words, there are 2 DC outputs (2 LT-3045 to provide 1A for each output) respectively for the power supply for 2 devices. One can set two independent DC ouputs simultaneously in different voltages as one in 3.3v and the other in 5v etc. I wonder if the 4 pieces of LT-3045 can be combined to make a single DC output for doubling the current supply? Are you using it as a single output or exactly dual outputs for 2 devices? Please advise. Thanks
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 樓主| 發表於 2018-6-15 08:19:46 | 顯示全部樓層
clplarry 發表於 2018-6-15 07:59
Hi Brother CKL
According to the board in the picture you attached for the LT-3045 (4 pieces) from  ...

You are right. Its design is dual voltage of 1A each. I use it as single voltage of 2A by:

1) short circuit the output ground of dual channel
2) short circuit the output voltage of dual channel
3) short circuit the reference voltage of dual channel

By short circuit the above 3 pins, you can multiply as many LT3045's as you want.
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發表於 2018-6-15 09:49:21 | 顯示全部樓層
CKL 發表於 2018-6-15 08:19
You are right. Its design is dual voltage of 1A each. I use it as single voltage of 2A by:

1) sho ...

Thanks for your clarification. As I noted that there are two independent trimmers for adjusting the output voltage, by shorting the reference voltage point, are either of the trimmers could be made setting voltage? Thanks
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發表於 2018-6-15 11:11:44 | 顯示全部樓層
xiaomi battery bank tested here:

http://www.hiendy.com/hififorum/ ... p;page=1#pid2582975

Conclusion: very high ripple/noise.

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 樓主| 發表於 2018-6-15 11:25:44 | 顯示全部樓層
本帖最後由 CKL 於 2018-6-15 11:27 編輯
clplarry 發表於 2018-6-15 09:49
Thanks for your clarification. As I noted that there are two independent trimmers for adjusting th ...


All trimmers should be trimmed to the same output voltage.
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發表於 2018-6-15 12:19:52 | 顯示全部樓層
本帖最後由 clplarry 於 2018-6-15 12:34 編輯
CKL 發表於 2018-6-15 11:25
All trimmers should be trimmed to the same output voltage.


Do you mean to trim the output independently to the same volt before shorting the 3 points as you said earlier? After having set the both output voltage at the exactly same level, the 3 points then shorted? But, for my understanding, only the two outputs are exactly the same without any micro difference (even the difference may be less as 0.01V), the two DC outputs will resist each other and will bring negative impact to the performance making the working temperture of the two LT-3045 rising gradually. Do you think that's the case? Please correct me if I'm wrong.   
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 樓主| 發表於 2018-6-15 12:51:59 | 顯示全部樓層
clplarry 發表於 2018-6-15 12:19
Do you mean to trim the output independently to the same volt before shorting the 3 points as you  ...

Yes, trim to the same output voltage then short circuit the 3 pins. When you short circuit the reference voltage pin, the output voltages would change to the same new value.
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發表於 2018-6-15 13:01:07 | 顯示全部樓層
CKL 發表於 2018-6-15 12:51
Yes, trim to the same output voltage then short circuit the 3 pins. When you short circuit the ref ...

Thanks for your further comments. I think the output Voltage only shows the value with the larger one. For example, if one is at 5.01V and the other is 5V, the display screen of the volt meter will only show 5.01V instead.
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 樓主| 發表於 2018-6-15 13:31:22 | 顯示全部樓層
clplarry 發表於 2018-6-15 13:01
Thanks for your further comments. I think the output Voltage only shows the value with the larger  ...


Before you short circuit the reference voltage, yes, the two output voltages may differ. But after you short circuit the reference voltage, the two output voltages would become the same because of the same reference voltage.
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發表於 2018-6-15 13:49:27 | 顯示全部樓層
CKL 發表於 2018-6-15 13:31
Before you short circuit the reference voltage, yes, the two output voltages may differ. But after ...

Thank you.
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發表於 2018-6-15 14:55:48 | 顯示全部樓層
CKL 發表於 2018-6-15 13:31
Before you short circuit the reference voltage, yes, the two output voltages may differ. But after ...

One more question please. What AC input voltage did you apply for 5V DC output setting?
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 樓主| 發表於 2018-6-15 16:00:10 | 顯示全部樓層
clplarry 發表於 2018-6-15 14:55
One more question please. What AC input voltage did you apply for 5V DC output setting?

9V AC is the best I think.
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發表於 2018-6-15 16:10:32 | 顯示全部樓層
CKL 發表於 2018-6-15 16:00
9V AC is the best I think.


Will it be too hot for inputting 9V AC for making 5V DC output?
For 9V AC x 1.414 = 12.7V DC
And 12.7V -5V = 7.7V.
It means for 1A output current 7.7V x 1A =7.7Watt will have become heat
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 樓主| 發表於 2018-6-15 16:40:23 | 顯示全部樓層
clplarry 發表於 2018-6-15 16:10
Will it be too hot for inputting 9V AC for making 5V DC output?
For 9V AC x 1.414 = 12.7V DC
And  ...

As shown, 7V and 9V are similar but 9V is better at 2A output. 9V is hot but acceptable.
noise.jpg
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 樓主| 發表於 2018-6-15 16:43:33 | 顯示全部樓層
clplarry 發表於 2018-6-15 16:10
Will it be too hot for inputting 9V AC for making 5V DC output?
For 9V AC x 1.414 = 12.7V DC
And  ...

12.7V DC is without loading, as the current loading increases, 12.7V DC would drop and drop.
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發表於 2018-6-15 17:02:59 | 顯示全部樓層
CKL 發表於 2018-6-15 16:43
12.7V DC is without loading, as the current loading increases, 12.7V DC would drop and drop.

On the other hand, I noted that AC input is not the only way. So many designs use DC as input to make DC output. Will it be better to use DC input? If yes, I think the input 9V DC is more than enough to make a steady 5V DC output. Do you think so?
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