|
![](/i/fill.gif) |
>> Of course, when you buy a kit, somebody else has already figured out
>> what kind of LEDs to put in there, and what resister you need to connect
>> it to. I recall routinely using ICs to drive LEDs - but that was TTL,
>> and now I'm looking at CMOS, which has different characteristics.
>
> Not that hard to figure out what kind of resistor you'd need to safely
> drive an LED for a given voltage.
I wouldn't have thought so.
> You subtract the Vf of the LED from the supplied voltage, then use ohms
> law to calculate the resistance you'll need to drive the LED in its
> current range.
My plan was to just connect it up and see if it works - but sure, your
way would work too. ;-)
> BTW, why CMOS? TTL is more robust for experimentation. CMOS you have to
> worry about damage from ESD, etc...
This was my initial reaction too. However, it seems that CMOS has
several advantages here:
1. It's fractionally cheaper.
2. It uses less power.
3. It has a much bigger fan-out.
4. It can source more current.
5. It works over a greater range of supply voltages.
Seems the only real disadvantage is static damage...
Post a reply to this message
|
![](/i/fill.gif) |