Subject:
|
re: ztx614
|
Newsgroups:
|
lugnet.robotics.handyboard
|
Date:
|
Wed, 19 Mar 1997 16:10:29 GMT
|
Original-From:
|
Jeffrey Strauss Morehead <morehead@ece.=IHateSpam=utexas.edu>
|
Viewed:
|
1542 times
|
| |
|
|
On Wed, 19 Mar 1997, Stefano Nardone wrote:
> > If I have interpreted the schematics correctly almost any npn can be used for
> > the ztx614. The 614 simply provides ground for the IR transmitter with a
> > collector current of about 3ma. The base current is set by the 10k R to about
> > (5/10k) 0.5ma. If I have calculated f=1/2*pi*RC for the TOC5 enabled
> > oscillator, then the frequency max of the IR output is in the kilohertz range.
>
> I think it must better be a darlinghton and it must support enough current: if
> you want to get 0.1A or more pulsed current in the IR led, the transistor must
> have a rather high current gain, more than that of an ordinary npn trans (by
> the way the base current is less than 0.5mA). Probably an N-MOS switch with the
> right switching V and enough current (BS170?) can be better...
How are you gonna get 100 ma through a 1k resistor biased by 5volts??
The max would be 5ma. I have *never* heard of a LED this size that can
handle more than 20ma!! This LED is tiny. I don't know where pin one of
the jumper goes to or its use but I know you can't pull more than 5ma
through that 1k resistor when the whole board has a supply of 5 volts.
>
> >
> > This all means that almost any medium power npn can be used!
thx,
jm
|
|
1 Message in This Thread:
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
