On Thu, 21 Nov 1996, Harry Tenopoulos wrote:
> Hello everybody
>
> I have designed a PCB for the company i work for which is used on an
> automatic machine..
> The board has 3 PICs on it (2 16C54 and 1 16C55)
>
> This board interfaces with 3 external power relays.These relays are
> signaled from 3 other reed relays on the board which are
> opto-isolated from the signaling PIC.
>
> When the power relays operate alone (not connected to the machine's
> motor) there is no problem. But when they are connected problems
> start. These three relays control a two speed bi-directional  220V
> motor. At the change of speed or direction the electronic circuit
> seems to be reset (it happens about once in 10 changes).
>
> Can anyone tell me what is happening ?


Maybe your Supply voltage (for the electronic circuit) breaks down
('Spannungseinbruch') --> Can you use a oscilloscope to check it out ?

bernhard

>
>
> Harry
>

Bernhard Schweighofer alias schweigi@sbox.tu-graz.ac.at
(Student at Graz University of Technology, Austria)