Thread: not enough current for relays?
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11-08-2015 #1
Hi,
how do i deal when a board / Pokeys57CNC does not output enough current on output 5v pins to switch a external relay / 8 channel relay board 5vdc /??
Leds light but not bright enough and no switching happens.
Do i buy their relay board which has other type of communication with the BOB or there is sth i can do to make the general Chinese relay board work
their board is 30eur versus 10 euro for general low high chinese relay board. and i need 2 .Last edited by Boyan Silyavski; 11-08-2015 at 09:10 AM.
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Boyan You don't say how you are powering the Pokeys board.
This is from the manual:-
[PoKeys57CNC requires external 6-26V power supply to be connected to the board in order for the device to operate correctly (device may not operate according to the specifications if the external power supply is not present). The device uses switching power converter to scale down the input power supply to 5V. The power supply should be capable of providing at least 2.5W.]
Last edited by Clive S; 11-08-2015 at 09:37 AM.
..Clive
The more you know, The better you know, How little you know
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11-08-2015 #3
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11-08-2015 #4
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11-08-2015 #5
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11-08-2015 #7
i read somewhere that the relays need more than that, ~80-100mA so at the end i bought the extra boards.
i wish sb simplified the stuff and said- " you need that board and that relay board or output board, cause otherwise you will not be able to do this and that " cause for me 50mA is like chinese.
how difficult would be to do that if you sell a product
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I think a lot of small relays will switch at about 15mA https://www.sparkfun.com/products/100 or even less
..Clive
The more you know, The better you know, How little you know
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17-08-2015 #9
Without a diagram of your particular situation, all we have to go on is this....
If you get a multi-meter & see what the resistance is between the Pokeys57CNC 0V rail & the relay board's 0V rail ....if it's high resistance , then there's no common path (& therefore this is why your relay's aren't switching).... you will need to link the 0Vs on both boards together. Voltage is always 'with reference to another point' ...i.e. the 5V on your Pokeys57CNC is in reference to the Pokeys57CNC 0V, the 5V on your relay board is in reference to your relay board's 0V...the only way you can make the 5V on your Pokeys57CNC mean anything to your relay board is to commonize the 0V rails on both boards....join them together.Last edited by HankMcSpank; 17-08-2015 at 11:44 AM.
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