Peter_wadley
New Member
Hi all,
Ive been a guest to this website for a while and I thought it is time to make a thread of my own!
I have been in my own little world of circuits for the last year and have learned a good amount of things that will help make next year alot easier as I am going to university for computer engineering in September.
Here are a few questions which are all fair game in this thread:
1) How much current can AAA,AA,9V,D and C batteries shell out, will they over heat and leak acid if they are overloaded? Can I run a 6.3v .25amp lamp with maybe 4AA batteries in series? (its for a fridge light)
2) Right now I am training with the PIC16F84a, I wanted to run a small DC motor from one of the PIC's outputs so I used the output, which has a low current capacity (20ma?), to switch a power transistor on which in turn powered the motor.
Problem: The output which I used to turn the transistor on now only reads @ 1V... even after reprogramming the PIC.. Did I overload and kill the output?? Note: this has happened to 2 seperate outputs on 2 seperate PIC's
To find the output - transistor base resistor I calculated:
5v-.7= 4.3v ;since transistors turn on when the base has a voltage of .7v I needed a resistor which will take 4.3v of the 5v's coming out of the output.
Since I didnt want to pull more then 20ma and kill the pic I chose a resistor value that would take the 4.3v at 5 ma..
V=I*R
R = V/I
R = 4.3v/.005
R= 830
So, I used a 860hm: resistor.
This went to the base of an NPN TIP31C power transitor.
The emitter went to ground and the collector to one lead of the motor (other lead went to 5+)
Did I mess this up and ruin the pic output?
3) I would like to try and use an infrared reciever as a switch for the pic. Is this possible? Ie IR ray is directed over the IR reciever input goes 1 or 0 - motor goes on.
Thanks all,
Peter W
Ive been a guest to this website for a while and I thought it is time to make a thread of my own!
I have been in my own little world of circuits for the last year and have learned a good amount of things that will help make next year alot easier as I am going to university for computer engineering in September.
Here are a few questions which are all fair game in this thread:
1) How much current can AAA,AA,9V,D and C batteries shell out, will they over heat and leak acid if they are overloaded? Can I run a 6.3v .25amp lamp with maybe 4AA batteries in series? (its for a fridge light)
2) Right now I am training with the PIC16F84a, I wanted to run a small DC motor from one of the PIC's outputs so I used the output, which has a low current capacity (20ma?), to switch a power transistor on which in turn powered the motor.
Problem: The output which I used to turn the transistor on now only reads @ 1V... even after reprogramming the PIC.. Did I overload and kill the output?? Note: this has happened to 2 seperate outputs on 2 seperate PIC's
To find the output - transistor base resistor I calculated:
5v-.7= 4.3v ;since transistors turn on when the base has a voltage of .7v I needed a resistor which will take 4.3v of the 5v's coming out of the output.
Since I didnt want to pull more then 20ma and kill the pic I chose a resistor value that would take the 4.3v at 5 ma..
V=I*R
R = V/I
R = 4.3v/.005
R= 830
So, I used a 860hm: resistor.
This went to the base of an NPN TIP31C power transitor.
The emitter went to ground and the collector to one lead of the motor (other lead went to 5+)
Did I mess this up and ruin the pic output?
3) I would like to try and use an infrared reciever as a switch for the pic. Is this possible? Ie IR ray is directed over the IR reciever input goes 1 or 0 - motor goes on.
Thanks all,
Peter W