Supplying 6 (or 4.5) volts to to a piece of equipment requiring 5 volts?

Question

I have a Canopus Analog to Digital Converter that I purchased awhile back to use with my computer. It can get power from the computer itself, but also has the option of purchasing an extremely overpriced power adapter from Canopus to use with the product when it is not plugged into a computer.

Well, I have a universal ac/dc power adapter that came with a set of different sized tips (one of them does indeed fit properly into the Canopus device) and a slider to select between 3, 4.5, 6, 7.5, 9, or 12 volts; however, the Canopus device says that it requires 5 volts. Would it be safe to operate the device using the universal ac/dc power adapter supplying either 4.5 or 6 volts? If I left this power adapter plugged in all of the time, would it eventually cause damage to the device?

Thanks!

Answer 1

You can try it on 4.5 but I don't think it will work, because it's 5 volt you need to go slightly higher than that, but 6 might be too much. If you try it and it doesn't work it may well mess up your converter. Good luck with that anyway.

Answer 2

The adapter you have doesn't quite hit the right voltage, but I think 4.5 should be ok (it won't hurt to try it.) 6 might be too much and so damage the device.  

You could also get a USB style phone charger. This is for sure 5V.

An editorial note. The USB power specification is notoriously bad when it comes to real world design. (Link below is an Intel paper discussing line droop issues.) Good USB device design practice uses a wider margin.

Answer 3

Be very careful. The universal transformer you describe is probably an unregulated power supply. In other words, it has no protection or voltage regulation to keep the output voltage constant. The slider is simply a way of connecting different lengths of the transformer coil and the voltage can be different to the shown value by up to 50%! Also, the voltage will change depending on the current drawn. Another drawback of these universal supplies is that they don't filter any line noise or spikes coming down the line, which may damage your convertor.

If your Canopus device uses CMOS circuitry (probably), it could be very sensitive to over-voltage and you could destroy it, even on the 4.5v setting. The expensive power supply is probably regulated and would protect the device.

Oh, and lastly, the values shown on your universal transformer is RMS voltage (Root Mean Square), sort of like the average voltage, NOT the maximum voltage. So a RMS voltage of 4.5v could actually vary between 3 and 6 volts. Again, a regulated power supply would keep this constant at the rated value.

Answer 4

how exactly is the spec for the Canopus device worded? does it say 5 +-0.25 volts, which is typical?

If so, then it means exactly that.

Also, I'd check the power adapter, many of these are poorly designed, with incorrect voltages, and lots of ripple. Is there a spec on it? With no spec, the voltage out could be anything.

If the adaptor is actually putting out 6 volts, you can put a rectifier in series with it to bring the voltage down to 5.2-5.3 volts, and that may be good enough for the Canopus.

But look at the specs. No specs, it's all unknown.

edit:

USB spec: "The specification provides for no more than 5.25 V and no less than 4.75 V (5V±5%) between the positive and negative bus power lines"

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