not enough current for relays?

[Boyan Silyavski]

Did not think of switching them directly.

Now i read that the relays i was going to use are triggered only by 5mA, so why would they not work?

By the way it looks a really quality stuff. and has LOW HIGH jumperson each pin. I have used it before with great success


Module Description :
1, the module uses genuine quality relay , normally open interfaces Maximum load : AC 250V/10A, DC 30V/10A;
2, using SMD optocoupler isolation , driving ability , stable performance ; trigger current 5mA;
3, the module voltage : 5V
4 , each way module can be set high or low triggered by jumper ;
5 , fault-tolerant design , even if the control line is broken , the relay will not operate ;
6 , the power indicator ( green ) , 8 relay status indicator ( red )
7 , interface design humane, all interfaces can be connected directly via terminal wiring leads , very convenient
8 , Module size : 141.5mm * 50mm * 18.5mm ( L * W * H )
9 , has four mounting bolts holes , hole 3.1mm, pitch 136mm * 44.5mm

[Clive S]

Did not think of switching them directly.

Now i read that the relays i was going to use are triggered only by 5mA, so why would they not work?

You would have to show how you are connecting them . It could be a problem in the way you are grounding them.

[HankMcSpank]

I have one of those relay boards (or at least one that looks remarkably like it) - I drive it directly with the 5V out from a CNCUSB Mk2/9 board digital output - no issues.

I'd measure the DC resistance of your relay coil...I'd wager you can probably short out that output 100 Ohm resistor (which should then see sufficient current to energize the relay) ...else play on the safe side & put something like a 10 ohm resistor across it (i.e. in parallel with it)

[cropwell]

You may have a faulty board. Try hooking it up to a 5v power supply and see if you get a relay operating with 5v from the same supply. Some boards I have switch the relay on with 0v and off with 5v. Also check the jumpers.

[HankMcSpank]

Actually ignore my last post...if your relay board is the same as mine, from recollection the 5V from your driving IO pin, doesn't energize the relay directly, but does so via a tranny/fet. Are you supplying the relay board with a separate 5V supply?

[Boyan Silyavski]

Actually ignore my last post...if your relay board is the same as mine, from recollection the 5V from your driving IO pin, doesn't energize the relay directly, but does so via a tranny/fet. Are you supplying the relay board with a separate 5V supply?

BOB is supplied with 24v, relay board with 5v. I use different supplies for galvanic isolation of BOB, sensors,etc.

[Clive S]

BOB is supplied with 24v, relay board with 5v. I use different supplies for galvanic isolation of BOB, sensors,etc.

Boyan Can you show just how you are connecting the relay to the board you might have to connect the -ve grounds to each other.