Re: Capacitor size


Jan Nielsen wrote:

Hi,

I have a simple circuit with a PICAXE that controls a relay board, when
the relay board is empty it works fine.
But when I put a simple 20W lamp on one of the relays (230Vac) the chip
resets very often when that relay starts/stops.

I have a 0.1uf on the power legs of the IC, how do I know what other
size is needed to prevent it from resetting.
I didnt make the relay board myself, but from what I can see there is no
caps on the board.

The relays use 12V where the IC is using 5V.
The 12V is from the powerinput, the 5V is from a 7805.

Does the reset pin need a cap?

It would be a really good idea to provide a schematic of your
circuit.The description is'nt really crystal clear :)
Are you sure that the PICKAXE can supply enough current to the relay
board when the lamp is connected?Measuring the current throught the
lamp should help.

What about the extra 0V pin the chip has (Picaxe 28X1, theres a pin next
to serial connection with 0V, although both 0V and VCC is on the other
side too).
It is generally a good idea when working with microcontrollers to
connect the two pins(Vcc and ground) that are provided on the 2 sides
of the chip to each other.This helps the microcontroller to source or
sink high current(high as in the maximum values specified in the
data***)

.