4 Channel 12V relay system issues.

Joey

Did you remove the jumper .. JD-VCC to VCC ?

You apply the 12v to JD-VCC  NOT THE VCC PIN

The 5v on the VCC pin is to power the Optocouplers ...

Also note that these turn on with a LOW so you need to reverse your ON/OFF code.

Typical poor Asian support.

The indicator LED's on the schamatic are drawn reversed.

Mark

     For anyone else reading this, the rest of the conversation went like this.

       Joey Thompson Jun 18, 2015 3:16 PM (in response to Mark Beckett)

     Let me see if I understand,

     I need 5V to vcc, and 12V to JD-vcc pin?  What is that jumper for then??

            Joey Thompson Jun 18, 2015 3:23 PM (in response to Mark Beckett)

               Its working now, I have no idea why it does, but I'll take it!  For the opto couplers, do you know the current draw?  I have it connected to a 1A regulator of which I am using 80ma so I assume 920mA is suffice for the opto

                couplers (all 4).

               Thanks, These are sold all over but seem to be poorly documented, I have used relays but I liked the idea of the opto couplers with the high current throwing around in there.

               Man I owe you, the LEDs and now this.

                      Mark Beckett Jun 18, 2015 4:35 PM (in response to Joey Thompson)         

               What is that jumper for then??

                    Many of these boards have 5v relays BUT you could easily power this from a 12v system.

               For the opto couplers, do you know the current draw?

                    Like most Asian support there is no value for the series resistor.

                    However the forward voltage of a LED is approx 1.4v, so 5v - 1.4 (opto) - 1.4 (led) = 2.2v

                    If we assume the resistor is 470 ohms 2.2/470 = 0.0046 or 4.6mA.

                    If the resistor is 220 then about 8mA, for 1k then 2mA.

                    Its safe to say you could budget 5mA max for each opto.

                    If you want to know how to work it out ....

                    find the datasheet for the opto, and see if you can measure or note the resistor value ...then you can do the maths above ..

                    Man I owe you, the LEDs and now this.

                    So mark my answer correct ... oh you can't its not a question.

                    You haven't found the hidden camera then ...

                    Mark

                           Mark Beckett Jun 18, 2015 4:40 PM (in response to Joey Thompson)

                         These are sold all over but seem to be poorly documented,

                         yes but it depends on what supplier you use.

                         Terry King is very good, he always tests and dicuments all his products, and the price is not much more, but guaranteed.

                         Opto-Isolated 4 Channel Relay Board

                         Try this page for additional info

                              http://arduino-info.wikispaces.com/ArduinoPower

                         NOTE the relays on the board are 5v.

                         Mark

Hi Mark,

The Asian schematics have a more serious problem than just the reversed diodes as the relay coils are shorted.

Nice clear analysis of the problem.

John

relay coils are shorted

Well spotted Sir.

Better make John's answer as Helpful ....

mark

I assume the issue is just with the schematics?

I understand a bit now why the jumper is there.  If the relays were 5V, then I only need to connect into VCC and the jump then shorts the VCC to the JD-VCC.  However since I have 12V relays, this jumper is worthless and should not be there.  I must connect 12V to the JD-VCC for the relays to function.

Not very intuitive at all.

The thing I need to figure out is my batter can get as low as 10V, will the relays still fire?  If not I need to get a 5V version.  The 12V was by accident.

Hi Joey, From my experience you will probably find that the 12 V relays will close at about 8 volts and release around 3 or 4 volts. If you have a variable voltage supply you can test this for yourself, just be careful to get the polarity correct so you are not shorting your power supply through the flyback diode.

John

These do not function at all at 5V nor 6.6V for if they did I would not of had any issues    It works well at 11.5.

Thanks for the info, I will give it a try and report back.

These do not function at all at 5V nor 6.6V for if they did I would not of had any issues

Did you have the jumper ON at the time ....?

jw0752 is quite right they will likely still work at 8v.....

Mark

Yes the jumper was on.  Believe me I tried nearly everything except connecting to the JD-VCC.

What is JD anyways?

Hi Joey,

I have no idea what does it means JD but I am sure someone has and will answer soon. Instead I was thinking to the problem of the relay working at 12 VCC In this case you can use - I think you have - a separate VCC voltage to drive the relays, i.e. ULM2003 with obviously the common GND with the board. So when you enable the darlington with the low VCC the external 12VCC closes the circuit and "click" the relay. It's a bit complicated as you add one more component but you save the accidental relays board without the need of a replacement. Take in account that ULM2003 is sufficient as it should not drain too much power as it is only to switch the relay while the power is managed independently by the other side of the relay.

Let me know if you need a sample darlington usage schematics with arduino.

Enrico

balearicdynamics

Enrico

It's been covered here

http://www.element14.com/community/message/152954/l/re-4-channel-12v-relay-system-issues#152954