First, I just deleted a mistaken entry. All of the circuits will produce, "drive on = relay on".
Use the MikeML circuit and add some resistance in the collector circuit. Probably less than 100 ohms.
However, I don't know why you want to mess about trying to take out 1.35 milliamps as if the relay board designer wanted a 5 volt circuit minus a tiny error caused by the value of R14.

i probably explained it wrong. the control signal can only give about 1.5amps (the connection right before the 4.7k in your latest circuit). that is what i am trying to limit. the relay part input amp part can be higher, no prob. like you said.

is this possible?

also, i would like to bring back a pull resistor too, to stop the floating. the leds kind of just barely glow now that i am missing it while in the floating state (not activated).

thanks for bearing with me through this. i think we are very close to a solution.

 

Bipolar transistors don't float, at least not at 5 volts and room temperature. No need to tie their base to ground.
Start throwing 3 amps through them with a 50 volt supply, and leakage current can get to be a problem.
Please be specific about which circuit you are using.
The input current is decided by the resistor in series with the base.
My last circuit showed 4.7k because 5V -.6V = 4.4V
4.4V/4.7k = .936 ma.

If you want the input current to be 81 microamps, use the 2N7000 circuit.

Meanwhile, may I suggest some reading?

http://forum.allaboutcircuits.com/threads/ohms-law-for-noobies-or-the-amp-hour-fallacy.69757/

 

I believe the 10K in post #16 is redundant, since the base of a BJT doesn't float. The 2.2K resistor allows ~2mA of base current with a 5V signal on the base. Even being very conservative, that's about 20X more than the OP needs. A 47K would probably be fine. At least I think so - aren't we talking about ~1.5mA in the collector-emitter loop?

Maybe we're solving different problems.

 

This is alternating between, "Ah-ha!" and "WTF?".
Patience is the best I can bring to the situation.

 

ok great! it is working and has all the right amp draws! I used the last mike circuit #12 posted. thank you for explaining that formula and the no floating.

i understand ohms law, but not transistors thoroughly yet.

thank you so much for the help! it really is appreciated.

 

There are several kinds of transistors, BJT, MOSFET, IGBT...
I can't remember how long it took me to get a grip on them, but it wasn't one day!

 

Hi again. I just found the spec sheet for the optoisolator i am trying to trip. It is a pdf attached. Now we don't have to go by the sellers webpage that was known to be wrong.

Could someone good at reading spec sheets let me know if our amp draw we figured out is high enough for this optoisolator in the spec sheet?

I am still using that final MikeMl2 circuit for the relay. Also found this more detailed relay circuit schematic, attached as well (i'm removing the power jumper though).

 

MikeML did all this in post #3. Is 100 ma more than 2 ma? Is 100 ma more than 20 ma? Yes, it is.

Of course, removing the power jumper will stop the relay from working, but that's up to you.

As I said to somebody yesterday, Let's quit beating this horse and connect some parts!
It's ONE transistor and ONE resistor.

 

you really take a stretch to be patronizing. if you don't want to help someone that knows a lot less than you then don't reply. go into a more advanced thread. you don't have to read these if you don't want to.

i know 100 ma is more than 2 ma. great thanks.

my question is what are the amps needed for the opto from the spec sheet. i would like to know the range.

the jumper is being removed because i plan to use two separate powers to give the circuit true isolation. it will still work.

 

Sorry. I thought your primary goal was to get this project working. My bad.
You are free to discuss the details as long as you want. Please forgive my impatience.

 

Are driving this circuit from an Arduino output pin?
Is the Vcc supply that is driving the collector of the opto-isolator the same as powers the 5V on the Arduino?

 

The specs for that opto cite a minimum 2.5mA forward current, quotes the current transfer ratio at 5mA, and says the maximum allowed is 50mA.

I'd be a little nervous designing a driver for it at ~1mA unless I had the experimental data to verify it will work that low. So if your controller can't do more than 1mA, you will indeed need the transistor circuit and not a direct connection.

Where did you get the output specs for your ES-5? As far as I could tell, it's putting out an analog audio signal, not a digital 0 or 5V. But I could have missed it.