4 Channel 12V relay system issues.

Question

I bought this relay system and it doesn't work

http://www.ebay.com/itm/231573073495?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Its a 12V relay system so I have to use 12V into the VCC and the input pins are driven by 5V. So I connect 5V in, the relays trip. The code is simple, digital high and low with a 1 second delay. Pins are output.

The little LEDS turn off and on as expected but the relays do not trip. I don't have a load on them but should not matter. If I use 12V as required into the VCC, the leds only turn on, then go dimmer, never off.

I have a common ground between the arduino and relay board as well.

What is going on?

I went ahead and 2nd day aired a 5v version, I will just run it off the same regulator as the arduino. Anybody have any experience with these?

I bought this relay system and it doesn't work

http://www.ebay.com/itm/231573073495?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Its a 12V relay system so I have to use 12V into the VCC and the input pins are driven by 5V. So I connect 5V in, the relays trip. The code is simple, digital high and low with a 1 second delay. Pins are output.

The little LEDS turn off and on as expected but the relays do not trip. I don't have a load on them but should not matter. If I use 12V as required into the VCC, the leds only turn on, then go dimmer, never off.

I have a common ground between the arduino and relay board as well.

What is going on?

I went ahead and 2nd day aired a 5v version, I will just run it off the same regulator as the arduino. Anybody have any experience with these?

mcb1 · Accepted Answer

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

jw0752 · Answer

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

mcb1 · Answer

relay coils are shorted 
 Well spotted Sir. Better make John's answer as Helpful .... mark

4 Channel 12V relay system issues.

Top Replies