Greetings, I'm having trouble wiring my sugar cube relay and did my research over the internet and this is the best I can find to be able to trigger the relay with D3. would you please share your feedback if it is right before I plug it in and blow things off.
NPN should be switching the high side. The diode should be reverse biased, cathode to positive.
pontiacbandit:
NPN should be switching the high side. The diode should be reverse biased, cathode to positive.
So it should be fine with image edited above.
No way to tell, the transistor leads are not labeled, relay pins either.
And you're still switching the low side, all you did was spin the diode afaics.
Look at the diagram in the forum thread I found and linked.
Low side switching is correct with an NPN.
pontiacbandit:
And you're still switching the low side, all you did was spin the diode afaics.
Look at the diagram in the forum thread I found and linked.
Yes, that diagram correctly shows low side switching, doesn't it?
Is the output of the ESP8266 board 5v or 3v3?
Is the relay 5v,
Paul__B:
Yes, that diagram correctly shows low side switching, doesn't it?
Damn, ignore me 
Brain is really soggy last few days.
What threw me was the op's diagram having the black wire at the top.
Inrush current may be too much for the arduino
What inrush current might this be?
Paul__B:
What inrush current might this be?
when you energize a coil, you create a magnetic field. there is an inrush at that point. it is not 5x like a motor or 2-4x like a solenoid, but when you are powering a relay from the Arduino power supply, you have a limited power available.
I have had to use a points booster. Designed for train points, it has a small cap that charges and a resistor that limits current to the cap. when switched, the cap delivers the power quickly, then the holding current can be delivered without problems.
Unfortunately, you appear to be mightily confused here!
Solenoids are inductors. An "inrush" current is the very thing that inductors prevent by nature. 
Perhaps you need to go and "brush up" on some basic electrical theory. 
I don't think I should need to go into a more detailed explanation, this really does not constitute any legitimate point of contention.
Now the "points booster" is a completely different matter. The capacitor is used to deliberately produce an inrush current in the solenoid, and that despite its behaviour as an inductor which is in the case of points actuators, quite minimal. There are two interrelated purposes to this. One is to make use of a lesser rated power supply than might otherwise be the case.
The second and more important, is that if the solenoid were continuously powered with the current used to move the points, it would quickly overheat and burn out. Railway points (full-scale or model) are switched by intermittent pulses, you neither need to nor can you power the solenoid continuously.
This is an entirely different matter to operating a relay or any solenoid which needs to hold its position.
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