GPIO'4'Cars, the way to drive your car with N2!

[zyssai]

This website is wonderful, I didn't know it. The fact to see which way the current takes, I will try to play with it. Perfect, thanks

I will take a look tomorrow with a relay, and see if it works.

[mad_ady]

I remember falstad.com since ~20 years ago, when the simulations were java applets!

[zyssai]

I remember falstad.com since ~20 years ago, when the simulations were java applets!

I've just seen how full it is with math and physics simulators. A little old school but that's the best

[mctom]

I was really angry making that simulation, that interface for adding components is awful.
I prefer SPICE simulators, but those are much harder to use, and harder to share.

One thing you should try is to simulate what would happen if you placed a relay on this output, and why it wouldn't work. Relay coil has some 100 Ohms...

The output voltage is 118 mV. Not quite enough

EDIT: My girlfriend said yesterday she'd like to finally try all that Arduino stuff.
I told her an inspiring story of our French friend who developed an actual product with a little community help.
If you say this is an intuitive and easy to understand representation, I'll use this tool to teach her about amps and volts..

[zyssai]

This website is old you're right but it does the job

I will delay test of relay but will try to add it to your simulation soon.
Happy to know there's some french guys helping with an anecdote

[zyssai]

So here it is
Look at how nicely the widget is, as it is changing regarding the state of the output



I replaced R2 with the same relay as the one used to power N2 with the ATtiny85, it is the exact same schematic.
For the test purpose I just wired a led to N2 1.8v directly to the relay.

I just consider to let user choice to use 12v or some sort of open/close contact.

[mctom]

You can add relay permanently, and provide all three relay contacts, so the user can make anything they want with it.

OR, to save cost and board space and mass, you can make a high side transistor switch instead of a relay.
Related picture below. You'll need a P-type MOSFET for this. Which one? This depends mostly on maximum current you wish to provide with this output.

Don't ever believe the MOSFET current rating in amps. What you want is Ron (On-state resistance) to be low enough so your mosfet doesn't get hot when conducting.
Assuming 100mW maximum loss, and 2A output current, Ron would be..

P = I * I * R
2A * 2A * R < 0.1W
R < 0.1 / 4
R < 0.025, or more commonly 25mOhm.

T1 may be 2N7000 that you are already using.
R1 = 10k will be fine.

[zyssai]

Good advices as always

It's sure relay takes place. The supported current of this smd model is 2A for 12V.
I will study MOSFET solution as soon as I have time to

[zyssai]

I will release, I think before end of May, latest LOS20 from @voodik, including all the necessary changes to make GPIO'4'Cars board working directly out of the box.

[zyssai]

I am actually redesigning an alternative version of the board, for the possibility to attach the N2 and the GPIO'4'Cars board, directly on the back of VU7C screen.
Second reason to this redesign is to remove BT module, because unfortunately I don't find it perfect for every day usage.

As you can see, it will fit like this:



This seems huge, but thickness including VU7C and N2 is around 58mm.
I will design a 3D printed support to fix them together.