See the video.
Hfe is irrelevant for a saturated (reverse biased) transistor.
Collector voltage should drop below base voltage for switching, and that needs more base current.
Look at the saturation graph of say a 2N2222.
Also look at common opto-isolated 5volt realy modules.
You will find the base resistor to be 510ohm.
Leo..
Guess I'm drunk or something... Are you driving a relay to drive another relay to drive something else?... what is the end 'object' you are trying to switch?
With all this complexity, I'd look elsewhere and dump the relays if possible....
You can directly drive a solid state switch or a mosfet from the Arduino, more dependable and you can rid yourself of the diode game.
Good luck
I see the 5V relay that puts power to the 'Heavy Duty' one? What does it switch, pick or do?
Thatâs the OPâs solenoid/load.
Why not run the 'OP's solenoid' directly? I would have switched it directly with a mosfet...
Toggling at 1.4 Hz, I hope you picked up a couple extra relays
There are times when we need galvanic isolation between the controller and the load.
This is especially true when there is a long distance between the two.
A relay will provide this isolation.
The OP could use an opto isolator too for the same reason.
We need to know the OPâs reasoning for doing things is in this design.
I don't see that here... the only isolation I see is the LM2596? Tied to the same rails and ground...
I hope he gets it working OK... he's been hammered on it enough 
The relay contacts offer isolation between the Arduino and the load.
For example, letâs say the solenoid and relay are 5 meters away from the Arduino, however, it is not wise to take 5v out that far 
.
This would be similar to a starter relay in a vehicle.
There is the common element, the 14v power supply, but as mentioned the buck converter offers a point of separation to the Arduino from the power supply,
Hope the OP doesnât think the same.
We need confirmation from the OP.
Guess you didnât see my overview schematic?
Indeed not! On the contrary Iâve had very useful help from you and others, so the âhammeringâ remains a puzzle. 
Your car starter analogy was very appropriate.
Iâm rather surprised if the purpose of my project wasnât obvious to all. A transistor-relay-heavy duty load is surely fairly commonplace? The load in my case is a large, ancient solenoid, and as prominently shown in my schematicâs title Iâve deployed it as a can shaker. Had fun with the mechanics.
As I said up thread, I intend to make some further changes, including a MOSFET, and I might also precede it with an opto-isolator.
Not sure if you needed any further info or confirmation Larry?
Means there is no possible electrical path between them.
A car starter solenoid is not an example of galvanic isolation. It is just switching a load on the same supply line... Once you 'pick' the solenoid, there is no electrical isolation between the 12V that is on the switch and the 12V on the starter.
If your 12V switch picked a relay that supplied mains AC to a device, I'd buy into that as galvanic isolation...
Nevertheless, I get what you're driving at.
Good luck
OK, understood thanks.
Applying this to my circuit I now see what you mean. The isolation stops short of being galvanic because my 5V and 14V supplies are not separated by a transformer. Only by circuitry in the buck converter.
Presumably inductive coupling is the only way to achieve galvanic isolation in power circuits, unlike opto-couplers etc for low power isolation?
I don't think the power (high or low) would restrict it as they can always use the power 'on the other side', if you follow.
An optical isolator will switch high current loads. I use a solid state relay to switch the ventilation on/off when my machine runs. It's driven by the Ruidas 'Status' sink. Draws < 20mA and can switch the mains at 30 amps.. they use galvanic isolated... you are driving an led...
Another place is with electric vehicles and hybrids seem to isolation issues..
I use power mosfets to drive similar circuits that you are driving with the transistor. They are dependable, easy to use and low cost. I commonly connect them directly to the output pin of the micro... They have a mili ohm 'on' resistance, so less power going to heat.
Good luck
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