HN3806-AB-400N requires 6 volts?


I purchased a HN3806-AB-400N from ebay, they state that it will function from 5 volts to 24 volts, however I don't get any output unless I use an external psu and raise the voltage to around 5.8 volts which means that the output will be too high to plug straight into my mega. As I've seen others using the 5 volt supply direct from the board I'm assuming that this particular encoder is not operating as it should? Just wondering if anyone else has had any problems with this type of encoder, any help or pointers would be appreciated. I don't really want to use any additional circuitry.


Not to worry, although the device does not produce an output until about 5.8 volts, the output is below 5.5 volts so it does seem to work ok with my mega. Just means I have to run it off a separate supply.

The encoder outputs are NPN open collector, did you put pullup resistors (4.7k to 10k) from input pins to 5V?.

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I would agree with JCA79B that you'd need pullups on the outputs. The open collector outputs are mainly to ensure the voltage is compatible with whatever system it's working on. Also with the Chinese components, sometimes the manufacturers are a bit liberal with the datasheets. You might want to make sure the PSU is accurate and if so, then pick up another device to check if it behaves the same way. If so, then either use a separate supply or add a boost circuit to the system you are working on.
Hope that helps.


I just got the same encoder from China.
Same issue, it will not respond when power supply is less than 5,8V.

Since I payed not too much I decided to break the warranty, opening the beast and checked the problem.

The problem is that they use a 78M05 Voltage regulator so that when powered with 5V it will not provide power at output.

I fixed it just shrt-circuiting the regulator since I am sure I never will use this encoder with power other than 5 Volts.

Now it works fine on Arduino