hi, sorry for my bad english,
it seems this question is silly,
i have 8 channel 5v relay,
but if i using more than 1,
the power of arduino seems to reduce,
because of that, i like to use external power,
after searching old usb cable and found nothing,
i found this old nokia charger 5.7v 800ma,
will it save to use it into relay external power input?,
thank for read
Kucingmiow:
i found this old nokia charger 5.7v 800ma,
will it save to use it into relay external power input?,
You'll need to check the datasheet for the relay, and by that I mean the actual relay on the module, not the datasheet for the module, which is unlikely to give that.
For example, the data sheet for the common Songle relay, says the maximum coil voltage is 110 or 120% (depends which model) of the nominal. So that would be 5.5V or 6V depending.
Read the datasheet for your actual one.
neiklot:
You'll need to check the datasheet for the relay, and by that I mean the actual relay on the module, not the datasheet for the module, which is unlikely to give that.For example, the data sheet for the common Songle relay, says the maximum coil voltage is 110 or 120% (depends which model) of the nominal. So that would be 5.5V or 6V depending.
Read the datasheet for your actual one.
thanks for the reply,
i buy without a manual book,
the content is a relay in antistatic plastic,
no serial id, just information about relay box,
5VDC
10A 250VAC
15A 125VAC
10A 250VAC
JQC-3FF-S-Z
i will assume it will dangerous,
but my brother gave me this just a moment ago,
old 5,3v-500ma nokia adapter, i will just using it,
thank again for the reply,
(deleted)
Kucingmiow:
i have 8 channel 5v relay,
Is that a module with 8 relays an a (5V) power connector?
If so, it's safe to apply 5.7V to that power connector, relays are quite permissive.
spycatcher2k:
DatasheetYou can use up to 6.5V according to the datasheet.
Weird the things you can find on GOOGLE.
thanks for the reply,
it not only the box,
but a bundle 8 channel relay with,
i come with small resistors, the chip with 4 legs, led lamps,
the most i afraid is the power will destroy the arduino, relay, and other module
Post a clear picture of your relay module and or a link where you got it from. This will help a great deal with figuring out what you exactly have and qhat it can handle.
Well, the picture was there i just did not see it, here you go:
Using the img tags makes it a lot easier for others to see your picture.
DrDiettrich:
Is that a module with 8 relays an a (5V) power connector?If so, it's safe to apply 5.7V to that power connector, relays are quite permissive.
yes is that thing,
how do you know it safe?
anyway thank for reply
Kucingmiow:
how do you know it safe?
How DrDiettrich knows is irrelevant; spycatcher2k already linked you to the datasheet of the relay you said you have (JQC-3FF-S-Z) which says 6.5V is ok.
I don't understand "8 channel" relay - do you mean 8 distinct relays, or a relay with 8 contacts?
Relays can not be connected directly to the Arduino, instead a driver (transistor) is required to turn a relay on. That's why beginners should use relay modules with built-in transistors and further helpful components.
All components with copper coils in it (relays, motors...) are dangerous to other components. The danger is not only possibly too high voltage or current requirement, very dangerous is also the EMF pulse when power to a coil is turned off. At least a freewheel diode is required against EMF problems.
Find out whether supplied parts (transistors, resistors...) are meant for building your own relay drivers, and how to build a usable relay driver circuit.
neiklot:
How DrDiettrich knows is irrelevant; spycatcher2k already linked you to the datasheet of the relay you said you have (JQC-3FF-S-Z) which says 6.5V is ok.
thank you, i just don't get if the JQC-3FF-S-Z representatives of resistor or other electrical things in the relay board,
i afraid the "JQC-3FF-S-Z" is will survive but the electrical thing wont
Lol you want to know if it is safe, 5 people tell you it is safe, then you ask how they know while they posted the datasheet showing you it is safe. And then you are still not convinced it is safe?
DrDiettrich:
I don't understand "8 channel" relay - do you mean 8 distinct relays, or a relay with 8 contacts?Relays can not be connected directly to the Arduino, instead a driver (transistor) is required to turn a relay on. That's why beginners should use relay modules with built-in transistors and further helpful components.
All components with copper coils in it (relays, motors...) are dangerous to other components. The danger is not only possibly too high voltage or current requirement, very dangerous is also the EMF pulse when power to a coil is turned off. At least a freewheel diode is required against EMF problems.
Find out whether supplied parts (transistors, resistors...) are meant for building your own relay drivers, and how to build a usable relay driver circuit.
Bringamosa:
Post a clear picture of your relay module and or a link where you got it from. This will help a great deal with figuring out what you exactly have and qhat it can handle.
i just upload image of it on my attachment in this post
Bringamosa:
Lol you want to know if it is safe, 5 people tell you it is safe, then you ask how they know while they posted the datasheet showing you it is safe. And then you are still not convinced it is safe?
silly me, i 'm not an electrician. some said in the internet = arduino external power must 5v only, i don't know if 5,7 is 5v safety range,
thanks for answer,
Bringamosa:
Well, the picture was there i just did not see it
I think he edited it in after you asked for it, so you're forgiven 
Ok anyway, so for that linked pic's relay module OP, take the yellow jumper (bottom right) off, and wire it like this, where the 5V shown below as the external supply would be your <6.5V.....
neiklot:
I think he edited it in after you asked for it, so you're forgivenOk anyway, so for that linked pic's relay module OP, take the yellow jumper (bottom right) off, and wire it like this, where the 5V shown below as the external supply would be your <6.5V.....
thanks, i will try it after i am done clamping the cable
neiklot:
I think he edited it in after you asked for it, so you're forgivenOk anyway, so for that linked pic's relay module OP, take the yellow jumper (bottom right) off, and wire it like this, where the 5V shown below as the external supply would be your <6.5V.....
thanks for info, i have test it, i do not need gnd from arduino, it still work, thank you
Kucingmiow:
i do not need gnd from arduino
Correct, because the control circuit is from Arduino 5V, through a resistor on the relay board, and into an opto-coupler which has an led inside, and out into an Arduino i/o pin. So it's nothing different from you hooking up an led across 5V and an i/o pin.
When the i/o pin is low, the led inside the opto-coupler lights up and controls a photo transistor also inside there, and energizes the relay coil. That's why you need a low on your i/o pin to activate: the current through that led is from the high 5V to the low 0V.
The opto-isolation completely divides whatever's happening in the relay from your Arduino, as a safety feature if say your relay is in turn switching the mains.
a silicon diode drops .6v across its terminals. put 5.6 v in, get 5.0 v out. just put a silicon diode in line and move on to the next hurdle.
Is that even necessary?- the coil can take over 6V anyway, according to the datasheet.
