Discussion in "Project Help" started by    kks    Mar 1, 2018.
Sat Mar 10 2018, 10:00 AM
#21


>I said it before, i have changed the project to secure car access system
Actually you said you were "thinking" of changing to a secure car access system.

>Goodness so now i need a limit switch too
No, you will need two limit switches.

>now i am stick with led.
You could have two LEDs, one for motor forward, one for back.

You unlock the car with an RFID key.
How do you lock it ?


ExperimenterUK


Yeah well our professor told us to do the car one because its less common. I fo have two led's, green and red. Just a question, is it necessary to apply resistor to the microcontroller for led. Cause it requires 330ohm and i have a 10k one. If i will apply that then the light will probably be very dim.


[ Edited Sun Mar 11 2018, 03:35 PM ]
Sun Mar 11 2018, 01:49 AM
#22
>Cause it requires 33ohm and i have a 10k one.
>If i will apply that then the light will probably be very dim.
Yes it will be very dim.
The suggested value is probably 330 ohms.
Anything from 220 to 1K should do. ( 1/4 watt)
Resistors can often be salvaged from old equipment.

You did not say how the door is locked.
You could swipe to lock, and swipe again to unlock, but it needs more code.
Sun Mar 11 2018, 07:47 AM
#23


Resistors can often be salvaged from old equipment.

You did not say how the door is locked.
You could swipe to lock, and swipe again to unlock, but it needs more code.

ExperimenterUK


Yeah i do have an old circuit of some speaker lying around, but i think the resistor are of higher ohms than 1k. I don't even have a voltmeter to check them.
As for the door locking again, you just have to swipe one to unlock and it will be locked again after some delay. Isn't that usually how all smart doors works. You do get a appropriate amount of time to pass. Ofcourse i could have added an sensor to keep the door opened as long as you are near to door, so that the door doesn't close on you. But it's too late now.
UPDATE: I did the connections and joined the negative of the leds to the resistor that i pried out of some old circuit whose resistance i am not aware of. I suppose it's more than 1k so i joined both the negatives to the same resistor. The positive is connected to the microcontroller for input. I did the same in proteus and it works fine there. But only my green led is lightning up in real. The red led doesn't light up for some reason. The soldering part is proper so i can't think of a reason why its not working. Does red led require higher voltage?


[ Edited Sun Mar 11 2018, 03:39 PM ]
Sun Mar 11 2018, 07:53 PM
#24
>As for the door locking again, you just have to swipe one to unlock
> and it will be locked again after some delay.
>Isn't that usually how all smart doors works.

Is this "secure car access system" to lock/unlock a single car
or a car park ?

> I did the connections and joined the negative of the leds
>to the resistor that i pried out of some old
>circuit whose resistance i am not aware of.

You can't just guess, assume and hope with electronics, things get damaged.
I'm not surprised is does not work.
Proteus is much more forgiving than the real thing.

Resistors have codes on them. Usually coloured bands
that tell you the resistance.

Your professor may want you to do the car project,
but you can't complete this project without the right parts.


[ Edited Sun Mar 11 2018, 07:56 PM ]
Sun Mar 11 2018, 08:10 PM
#25
It's Society car access system, where only the cars belonging to the members of the society will have access to its parking area. That way no outsider can come in and park their car.
I didn't knew that the color bands indicate resistance. I broke quite a few resistors today trying to get it from the circuit.
The reason i went ahead with the connection is because i thought a high resistance unlike low can't do much damage to anything.
Actually in Proteus, the led does get dim when apply high resistance. My green led is glowing alright but the red one is really very dim, almost unnoticeable.
I just need a low resistor now. Have to complete this project by Tuesday.
Sun Mar 11 2018, 10:47 PM
#26
http://www.resistorguide.com/resistor-color-code/

>The soldering part is proper so i can't think of a reason why its not working.
>Does red led require higher voltage?

There is a slight difference, but not significant.
More likely the red LED is the wrong way round.
Try the red LED in place of the green and try it both ways round.
It should light up.
If not, it is faulty.
Let me know the result, meanwhile I will look at the code.
....
I have sent a PM.



[ Edited Sun Mar 11 2018, 11:38 PM ]
Mon Mar 12 2018, 01:11 AM
#27
It isn't faulty, but very dim. I tried it both way round, it does light up but you have to be in a dark room to actually see it. The green ones working fine either way, its not the brightest but it can be seen. BTW thanks for the code.
Mon Mar 12 2018, 05:07 AM
#28


It isn't faulty, but very dim. I tried it both way round, it does light up but you have to be in a dark room to actually see it.

kks


If it is much dimmer than the green one, it is probably faulty.
Mon Mar 12 2018, 06:54 PM
#29
As i said, it just needed it's own resistor. It's working perfectly now. Thanks a lot for all your help. It's really hard to find people like you who spend time to answer your doubts everyday. Seriously without you i wouldn't have been able to complete this project!
Wed Mar 14 2018, 10:46 PM
#30


Thanks a lot for all your help. It's really hard to find people like you who spend time to answer your doubts everyday. Seriously without you i wouldn't have been able to complete this project!

kks


Thanks for that.
I hope your project goes well.

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