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I recently bought a small 3 to 1 HDMI Amplifier Switcher. It can work without power adapter only if the 3 HDMI inputs are connected and supplying current. I want to operate it with only 2 input which is impossible without DC. On specifications it says that it needs a 5V p-p(TTL) signal while it has a maximum power consumption of 5W. What kind of power adapter should I ask from a store for this product ?

EDIT 1 : After request, I post the specifications of the device.

enter image description here

enter image description here

EDIT 2 : The DC Input of the device.

enter image description here

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  • \$\begingroup\$ 5V p-p(TTL) is a rather odd way of specifying the voltage requirements. Are you sure about that? Can you post a photo? \$\endgroup\$
    – Steve G
    Aug 13, 2019 at 7:59
  • \$\begingroup\$ @SteveG I added the specs images. \$\endgroup\$
    – NickDelta
    Aug 13, 2019 at 8:23
  • \$\begingroup\$ I would be highly suspicious of a spec sheet that says "no power required for standard product" and on the next line "Power consumption (max) 5W" ... \$\endgroup\$
    – danmcb
    Aug 13, 2019 at 8:28
  • \$\begingroup\$ @dmb I know...But they have some point. As I explained above, no power adapter is required if the 3 input cables supply current. The point is I want only 2. \$\endgroup\$
    – NickDelta
    Aug 13, 2019 at 8:37
  • \$\begingroup\$ does it even have an external DC input? if so what does it look like? photo? \$\endgroup\$
    – danmcb
    Aug 13, 2019 at 8:41

2 Answers 2

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Well, it is an odd way of saying it needs 5V DC in the datasheet, but that seems to be what they mean based on the picture of the device itself.

The connector is standardized, yes, and it is called a "DC barrel jack", or some variation of that. There is different sizes of the DC jack available, measured in inside diameter, outside diameter and length of the jack itself.

For power requirements, it needs 5V with a power draw of 5W, so a 5V/1A AC/DC adapter would be suitable.

One caveat though! It is not defined if the inner part of the jack is the positive terminal or the negative terminal. Based purely on experience, i would get one with a positive inner terminal, but no guarantees!

Edit: Look at the comment from dmb, he has a good point regarding testing the polarity of the jack

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  • \$\begingroup\$ right. If you have the lab gear try it on a current limited PSU and slowly bring up the limit. Hopefully there are some protection diodes in side if you get the polarity wrong ... \$\endgroup\$
    – danmcb
    Aug 13, 2019 at 11:06
  • \$\begingroup\$ Thank you, I'll try dmb's approach and find the suitable adapter. \$\endgroup\$
    – NickDelta
    Aug 13, 2019 at 11:27
  • \$\begingroup\$ In case anybody wants to know more about reverse polarity (warning, humor might be included in the following video): youtu.be/At0advb9_fA \$\endgroup\$
    – Fiskelord
    Aug 13, 2019 at 11:44
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It needs 5V 1A power supply. It does not say what connector and polarity. Officially HDMI sink devices may not consume more than 10mA (50mA when turned off) and sources must limit current to 500mA, so this HDMI switch violates the specs in many ways and simply can't work properly without external power supply.

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  • \$\begingroup\$ Based on the 3rd picture, can you tell if the connector is at least standardized and if yes, what kind of connector it is ? \$\endgroup\$
    – NickDelta
    Aug 13, 2019 at 10:10

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