Hi,
On a hobby basis I'm trying to figure out how electronics works
I'm doing this by buying a lot of kits (a real TPAddict as measured by the hight of boxes I have accumulated!!!), assembling them, and trying to understand how they work
I must be very dumb because I cannot even understand what the transistor is doing on the OTTO board.... Somebody please enlighten me

Thanks,
Nic

P.S. I hope that Brian's moving is over and that: AC1, Ballsie Lite, Placid will be available soon

Thanks Brian,

Now I understand (at least I think so....) and look even more forward to AC1!
According to the data sheet the coil resistance of the relay in question is 69R. With 5V this yields 72.5 mA (the figures you indicated......).
If I'm not to stupid this means that I can use this relay with a switch and a 5V source without the need for a current limiting resistor. Correct?
Is this generally true for relays (i.e. that a current limiting resistor is not needed)?
A yes/yes answer would be comforting.

Thanks again,
Nic

P.S. With a retail price in Europe of around 15 euro (about 20$) for the relay alone your OTTO is a real bargain!!

Edited by user Friday, June 5, 2009 3:42:08 PM(UTC)  | Reason: Not specified

Yes, the resistor is only for feeding the base of the transistor, not the relay, so if you are switching 5V directly, you don't need either the resistor or the transistor, but would need to add a little jumper on the board to get the 5V to the relay coil.