W
[email protected]
- Jan 1, 1970
- 0
Greetings,
How to connect an LED to the PCs PPI and make it glow by program?
Thanks in advance.
How to connect an LED to the PCs PPI and make it glow by program?
Thanks in advance.
Greetings,
How to connect an LED to the PCs PPI and make it glow by program?
Thanks in advance.
Greetings,
How to connect an LED to the PCs PPI and make it glow by program?
Thanks in advance.
Greetings,
How to connect an LED to the PCs PPI and make it glow by program?
Thanks in advance.
Greetings,
How to connect an LED to the PCs PPI and make it glow by program?
Thanks in advance.
ehsjr said:
So if it's 2.6 mA max (data pins to ground), are the 470-ohm resistors
still necessary? (grin)
Michael
Ya know, this is kind of interesting.
http://www.taomc.com/bits2bots/litbit.htm
(Amazing what one can learn when trying to answer someone else's
question.)
I have a new question for the group. I don't have any LEDs lying
around, but I have a few light bulbs lying around. I know that the
data output voltage is 5V, but what is the maximum safe current to
draw? I'm guessing that, since resistors are required for the LEDs,
the current is fairly high - hundreds of milliamps, I'm guessing. But
I also wouldn't want my light bulb to fry my parallel port, if it draws
too much current.
So if it's 2.6 mA max (data pins to ground), are the 470-ohm resistors
still necessary? (grin)
Michael
ehsjr said:Where's you get 470 ohms? That won't limit the current enough.
Ed
ehsjr said:Where's you get 470 ohms? That won't limit the current enough.
Ed
Oh, good point. Got that from a random page on LEDs.
To limit current to 2.6 mA, I'd need 2 k-ohm, right? (R = 5V / 0.0026A)
I posted a page on my website re: controlling a light bulb by parallel
port:
http://mrdarrett.googlepages.com/blinky
Is a 2 k-ohm resistor big enough? Should I make it larger, just to
stay on the safe side?
Coming soon: PWM motor control via parallel port.
Michael
ehsjr said:You don't get a lot of base drive with that 2K resistor,
and yet you want to be darn sure you protect the port.
If you really intend to drive an incandescant bulb, you'd
be better off with a darlington, like a TIP120. In terms
of figuring the base resistor, you would be able to use a
4.7K. The TIP120 in your circuit with 4.7K base resistor
could drive a bulb that needs up to 1 amp.
Ah. I was planning on driving even bigger loads than my incandescent
lamp. I drove a 1A 12V blowdryer fan with an IRF530, with the setup on
my website. My MOSFET got kinda warm - about 105 F with a heatsink.
(I used a diode and two caps as the 555 PWM circuit recommended.)
Is a 3.3k still good for an IRF530?
Thanks!
Michael
(Amazing what one can learn when trying to answer someone else's
question.)
I have a new question for the group. I don't have any LEDs lying
around, but I have a few light bulbs lying around. I know that the
data output voltage is 5V, but what is the maximum safe current to
draw?
I'm guessing that, since resistors are required for the LEDs,
the current is fairly high - hundreds of milliamps,
With regard to your IRF530 - putting 5 volts on the
gate won't turn it all the way on. The resistor at
3.3K would be fine*, but the gate voltage is low.
* = you need very little current on the gate - except
when you need rapid turn on. But your 5 volts already
is a problem which superceeds that.
Ed
ehsjr wrote:
...
Gate fully open at 10VDC, then? (from reading the V_GS charts on an
IRF530 spec sheet from digikey)
Michael
ehsjr said:10V will turn it on for you to drive heavy current,
(presumably) like the motor will draw. I don't know
what "gate fully open" means - I assume you mean
turn the mosfet fully on.
Ed