Subscriber Discussion

Power Rating Controller / Readers

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Gani Omobolaji Oladipo
•Jan 23, 2018
IPVMU Certified

Hello Brian

I just noticed that there are some readers whose specification is 12-16VDC, and we are specifying controllers of 12-24V to work with it.

My experience is that I see the readers as having 16V maximum voutage rating, while the controller supplies normally 24V, which according to the distance of the reader from the controller could drop to 12V before reaching the reader because of cable resistance.

If that is true (in this case), if a reader is close enough to the controller, it will receive 24V. This is 50% above maximum rating and can cause the reader to Zap frequently.

What is your take on this?

Gani

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Brian Rhodes
•Jan 23, 2018
IPVMU Certified

It's a good question.  Here are some facts that can help:

1) Reader input voltage is listed as a nominal (ideal) value, but the device itself can function in a range of voltages.  12 V to 24 V seems drastic, but in terms of modern electronics, it isn't.  A reader spec may list 16 V, but that does not mean it stops working or burns up at 16.1 V, not by a long shot.  It just means the other performance values are contingent on 16 V.

2) Devices like readers (or security cameras) use a overvoltage protection circuit to condition input power.  Circuitboards may support 16 V input, but immediately after power connections are made, the board wicks it down to 5 V or 3.3 V or whatever voltage ration vs amperage is needed by the components.

Readers are generally pretty tough little devices.  Even the normal ambient temperature impacts to voltage levels in the device don't break them, some last fully exposed to all sort of nasty, dirty power supplies and still do not break over decades of use.

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