|geoff adams||20/12/2017 18:22:21|
|180 forum posts|
having trouble wiring this up I know nothing about electronics
this is for my boxford lathe that I,am fitting a variable speed moter
please see the info supplied
the sensor has three wires brown blue and black I assume that these connect
to the readout and the other two are the power
can I use a 12v phone charger ?
any help please Geoff
|Clive Brown 1||20/12/2017 18:44:06|
|500 forum posts|
Sensor wires as per colour. +ve power to terminal 1. -ve power tp terminal 2. Terminal 4 not used.
'Phone charger is unlikely to give enough volts. 8+ v. is needed
The magnet needs to present the "correct" pole to the sensor, which lights up when it's working, or at least, mine does.
|geoff adams||21/12/2017 09:42:10|
|180 forum posts|
wired it up as per your instructions this morning now works a treat
|JIm Powney||03/07/2018 11:01:02|
|1 forum posts|
I have the same Chinese tacho with a hall sensor as the first post
We have a Large Mixer that we want to display the RPM for operatives
I Have wired as above diagram from a permanently fed 24vdc supply within the mixer and also tried the Blue sensor wire to either terminal 2 or 3 (0Vdc and Scn earth) and works the the same on both (as proposed in the below link) with Terminal 4 unused
We have also tried teh Black sensor wire to all pins including swapping teh Black/Blue cables to see if that made any difference but seems to function
However, we get 0000 displayed on tacho and red LED on back of hall sensor - as expected with voltage applied and Shaft NOT TURNING
regardless of how we wire the combinatoin of VDC/Tacho/Sensor when we start the shaft rotation the tacho shows 4 dashes "- - - - " and does not change even though the sensor seems to react to the magnet when the shaft is NOT spining
Does this sound like a faulty Hall sensor or some kind of voltage interference from the mixer itself?
the 24vdc comes form terminals connected directly to a 24vdc rectifier which is fed from a 220/24vac transformer
Do I really need a dedicated DC Voltage supply?
Any help appreciated
|Brian Sweeting||03/07/2018 14:49:02|
|442 forum posts|
Turn the magnet around, north to south poles or the other way, this caught me out when I installed mine last year.
|Harry Wilkes||03/07/2018 15:07:06|
981 forum posts
The hall sensors I have used favour the south pole
6313 forum posts
The output from the rectifier will be pretty rough and might well explain your symptoms. Electronics vary in their ability to cope with horrible power supplies but generally they don't care much for mucky DC. The voltage may also be more than the tachometer can cope with. (24V RMS has voltage peaks nearly 3 times higher, ouch, and the poor thing might be damaged.)
I'd clean up the rectifier output with a down converter unit like this example. I'm not sure this particular unit is suitable because it also has to deal with whatever your 24V rectifier is poking out, but the type cover a wide range of conversion voltages. A different model may be more appropriate.
Otherwise a laptop PSU or wall-wart would do the job if there's room and you're confident wiring it safely to the mains.
Electrical noise from the mixer itself is a possibility, but the most likely route into the electronics is via the power supply, and a better PSU should clean it up too.
Are you able to test the setup by powering it temporarily from a battery? If it works OK off a 12v car battery or similar, it must be a power supply problem.
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