crullier:
So going back to this image, how is the author / or why is he suggesting that we can use 12v on the Collector after the relay?
Because he is using an NPN.
Thanks for the help guys,
I got a replacement leonardo bord and after much reading and testing I switched the scheme to have a NPN transistor and wire it all as suggested by the 2nd schematic David provided. Thank you David ! - I got it to work.
David, I dont understand the last schematic. What do you mean by the CAUTION? where is that 5 volts coming from?
my connection is actually like that where I am using 12v on the transistor, and also to power the Arduino.
PS: what software did you use for those schematics?
BTW. I had received two boards today and killed one originally when I connected the 5v output to the base of the NPN transistor without a resistor... Then I used a 10Kohm on a new board and its working "fine". Why did my board burn?
I want to present this in the future. I have gone through two boards already... I can't keep doing this =(
crullier:
I switched the scheme to have a NPN transistor and wire it all as suggested by the 2nd schematic David provided. Thank you David ! - I got it to work.
The "2nd schematic", that in the middle, uses a PNP transistor.
What are you doing?
With regard to the schematic symbol for a transistor, whether PNP or NPN, do you understand that the Emitter (E) is the terminal with the arrow, the Collector (C) is the opposite terminal without an arrow, and the Base (B) is the terminal going perpendicular to the flat?
crullier:
BTW. I had received two boards today and killed one originally when I connected the 5v output to the base of the NPN transistor without a resistor... Then I used a 10Kohm on a new board and its working "fine". Why did my board burn?
I want to present this in the future. I have gone through two boards already... I can't keep doing this =(
You're using random means in the hope of achieving a rational result.
Learn to love resistors. They are your friends.
sorry I made a typo and dyslexia kicked in at the same time. So no, I am using ye first schematic with the npn transistor and 12v. And it's working fine I think.
Yes I really need to warp my head around transistors and have tons to learn. I appreciate all the help.
You are right my ignorance makes me do a lot of trial and error and has costed me several transistors, one relay and two arduinos. But, I think it's a fair price to pay considering all the help I am getting from you guys.
So thank you.
Ps: I am asuming, that the first time I connect the circuit, I exceeded the amp draw of the arduino trying ti actuate the base of the npn and killed my board. That made me realize that there IS a difference between volts and current.
I dont understand the last schematic. What do you mean by the CAUTION? where is that 5 volts coming from?
my connection is actually like that where I am using 12v on the transistor, and also to power the Arduino.
5 volts is coming from the Arduino.
Arduino +5 Volts is connected to the Relay +12 Volts, this is a connection that beginners normally do not do.
If you forget that you have done this you might later come back and add some extra hardware to your circuit where the new hardware needs you to connect the Arduino GND to the 12 volt GND. THIS WOULD DAMAGE YOUR Arduino ! Therefore in the 3rd (right hand) drawing DO NOT Connect the 12 volt GND to the Arduino GND!
To draw the schematic I used WINQCAD (no longer available ).
Search the WEB for other software ex: Eagle, KICAD, Fritzing
