Are EveryCircuit Drawings Valid Here? (And -of course- some other questions)

[Asheekay]

So ... during a frustration-filled internet grazing (instead of browsing) last night, I stumbled upon EveryCircuit. And boy do I love it already! After playing with it all night and feeling a huge urge to upgrade to full version, I thought it's better to ask the pros before spending the bucks on a simulation software.

Do other members use it too?

Is the 15$ cost justified? (I feel highly inclined to it, but I'd hold it if advised against)

If this is not the most noob friendly simulation software (in an affordable price), which is?

Also, about this circuit:

How accurate do you think their current calculations are, considering I, the noob user, only get to choose power supplies based on voltage?

And lastly, is there a means to lighten up that LED with an even smaller voltage input from the left-side batter (the one providing 787 mV)?

And last lastly, in real life circuit, I'd need to connect both grounds. Yes?

 

[rjenkinsgb]

I've not seen that particular program; I don't use simulators much, just LTSpice which many others one here use, it's free from Analog Devices.

LTspice Simulator | Analog Devices

LTspice® is a high performance SPICE III simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators. Learn more about the benefits of this simulator software.

www.analog.com

For info, the ground points in your diagram are already interconnected - when you use the symbol for "ground", that automatically connects it to all other points using the same symbol.

With many systems, the same applies to any defined or preset power symbols; eg. if it has +5V or +12V symbols, all of those would be interconnected with others of the same voltage.

That would not apply to individual voltage sources, as in your example diagram.

 

[JimB]

I am not a simulator user, so I cannot comment on whether EveryCircuit is good or bad.

Please look at my crudely edited version of your circuit:

My first suggestion is that you draw circuits more like this, it is a common beginners mistake to draw circuits in some odd weird style.

Your circuit does not have any current limiting resistors.

In my version of the circuit, R2 sets the current through the LED.
If we make R2 = 1k, then the LED current will be approximately 9v/1k = 9mA.

Similarly the base current is set by R1.
Try setting the voltage source which is currently 787mV to 5v, and set R1 to 10k.
This will give you a base current of (5 - 0.7v)/10k = 0.43mA, which should be sufficient to turn on the transistor.

JimB

PS:

during a frustration-filled internet grazing

Try railways as a diversion from this electronic stuff.

 

[audioguru]

Your SIM program has a nuisance grid in the background, green dots all over some of the wires and you drew the parts too far apart.

How did you select the input and output currents to be exactly 100 times apart when you cannot buy a transistor with an hFE of exactly 100? Some will have an hFE of 40 and some will have 400, even if they have the same part number and same manufacturer. Also, the hFE changes with temperature and voltage.
Since the hFE of a transistor is a variable which might instantly burn out the LED then you should design the circuit so that the transistor saturates with a base current that is 1/10th the collector current, and use a current-limiting resistor in series with the LED.