i hooked up my arduino to 5 transistors, all being used to switch relays. one relay is a 30 amp relay, but the others are all 4 or 5 amp relays. seems that for some reason only the 30 amp relay won't turn on and oof, but thats the least of my problems for now. Everything seems to be hooked up correctly, and the relays all work correctly, turn off and on as noted in the code. the bad prt is that the arduino gets VERY HOT VERY FAST when i have all the relays turned on. its very very hot, but its not failing, and i have no idea what is wrong. One thing i know i didn't do is connect the protection diodes noted in some exapmples, but other then that everything seems to be wired correctly because everything is functioning. im not sure if just the missing diodes could be causing this problem.
please help me fast before my arduino melts!! ( and ofcourse i have everything disconnected for now... )
Agreed. I think I read the absolute max current draw from the pins is 200mA (max 40 from each individually), but you shouldn't come ANYWHERE near that ever :P.
a picture will take me a long time to upload, but here is the simple way i have every one hooked up.
arduino output pin goes to the middle pin ( allegedly the base ), then i have my relay attached directly to the transistors left most pin ( allegedly the collector ) and finally i have vcc connected to the right most pin ( allegedly emitter )
and if your looking at the transistor the correct way, i have the circular part pointing away from me and the flat part pointing twards me ( which i looked up to to be the correct front )
and the transistors im using are 2n2222
of damn... i just realized some of the things im using arent transistors... im not sure but it's label sais 2n3904 and 2n4401... oops, ill try and hook up the 2n222's but i think those other ones are still transistors...
and to the claims of not drawing too much current, i know the relays alone will draw too much current, but i thought the transistors are sapposed to stop that
then i have my relay attached directly to the transistors left most pin ( allegedly the collector ) and finally i have vcc connected to the right most pin ( allegedly emitter )
Is it just me or is that COMPLETELY backwards? I'm not Transistor expert, but I'm pretty sure the VCC is supposed to come in through the collector, and then the component (and eventually ground) is supposed to be attached to the Emitter?!
im not sure but it's label sais 2n3904 and 2n4401
By the way, those are both still transistors, but I don't know what they're rated for.
ok i switched all the random transistors for 22222's, but still get the warmth... i would agree with your statement, but only two things don't make sense, first, wouldent the transistor not work if i had it hooked up backwards? and second of all i asked before how to use them, and this man told me i have it wired correctly, here is the post;
arduino output pin goes to the middle pin ( allegedly the base ),
For normal transistors, you should have a resistor between the arduino pin and the transistor base. The base looks like a diode to GND (all else being set up right) and will draw lots of current unless the resistor limits it. For most transistors, something of about 1k ohms should be close...
TchnclFl is right too. Normal current path for a relay is +V, coil, collector, emitter, ground.
using 1k resistors between the arduino pin and the base, none of the relays turn on. do i need a lower ohm'd resistor?
AHA!! i simply pulled out the transistors from my breadboard and flipped them around ( so front is now back, and back is now front and they are working with the resistors! and the arduino seems to be staying cool!!
thank you guys!
and even the 30 amp relay is working! holy moly, thank you!
and i dont really think thats your problem, it doesnt take much to switch a transistor, and your relay current should not have ANYTHING to do with the avr chip
I tend to agree here, you have the transistor in the wrong place, it should be switching on or off the connection to ground, not V+
AHA!! i simply pulled out the transistors from my breadboard and flipped them around ( so front is now back, and back is now front and they are working with the resistors! and the arduino seems to be staying cool!!
thank you guys!
and even the 30 amp relay is working! holy moly, thank you!
Holy cow they are! I never noticed that before. I'm just in the habit of just grabbing the data-sheet to look at before I hook anything up. I never noticed that they are exactly backwards of one another.
haha this works so well and it's so fun!! p.s i havent noted what its for, but i have all these relasy connected to ALL the lights in my room!!
i have 5 different lights in my room ( 3 main lights running the distance of my room, one standing spotlight with 3 light in it, one light over my bed, one desk lamp, and one ceiling mounted spotlight. i was able to cut small extension cables, and insert relays into them for all the lights that hook up to sockets, but the lights actually hard wired into my room like the three that run the distance in my room, and the ceiling mounted spotlight i had to take apart and actually hard wire a relay into the sysytem, along with putting a pigyback so i could still control them manually! now with the working transistors, EVERY LIGHT works!! i have a simple sketch where the lights that are on rotate, so now im sitting in my room with my lights turning on and off consecutively! Thanks again for all the help, i hope to use this to make a very environmentally safe way to save electricity! ( i have a motion sensor mounted by my door, so when i leave all lights turn off if i set that up ).
Do you mean the plastic 2n3904 vs the metal can 2n2222a? I guess. But the plastic 2n3904 and the plastic PN2222A have the same pinouts (or please tell me which datasheets you're looking at!) As far as I can tell, there's no such thing as a plastic 2n2222a...
