Dying Stamp

Archiver

I've been having a problem of my BSIIsx dying...I've managed to make
two of them stop working and am wondering what I could be doing wrong.

At this point, it's either (a) a basic power supply problem or (b)
something I'm doing incorrectly in the way that I'm driving my
components.

(a) power supply: it's my understanding that the V... input pins
should be used in such a way:

Input:
Vss = ground
Vin = unregulated power supply
Vdd = regulated 5V power supply

Output:
Vdd = regulated 5V output
Vss = ground

I'm using Vin for the power supply, supplying 6V from a wall
transformer. The BS has a separate power supply from everything else.

(b) components:

I'm driving 2 sets of components:
1. a solenoid valve -- this is drived through an AC solid state
relay, triggered by one of the output pins, hooked into the stamp's
power supply ground.

2. a sparking mechanism -- this is also triggered by one of the
output pins, but through first a DC solid state relay and then a
standard coil relay. It has a 12V power supply.

So, the power supplies and circuits are electrically isolated as far
as I can tell.

Any ideas?

Thanks,
Scott

Archiver

I beleive your problem to isolation in nature. You likely have back voltage
spikes returning to your outputs and possibly to your inputs. The operation
of relays and coils involving coils induce a back EMF voltage due to
collapsing magnetic fields. Best to shunt these voltages to ground through
the use of diodes. Orient the diodes with the cathode connected to the relay
output node (relay on) and the anode to ground.

Bruce Wynn

Archiver

Thanks for the response here.

After doing more research about the solid state relays, I think that
the LEDs from the SS relays are consuming too much current. For SS
relays, the more often you activate them, the more current they will
draw and I'm activating them at 200 ms intervals.

So, triggering them through a transitor should solve the problem,
since this would draw less stamp current.

Since I'm using solid state relays, it wouldn't be possible (would
it?) to get a voltage spike going from the output back to the input.
There is no coil in a solid state relay and the only time I use a
coil relay is when it is triggered by a solid state relay.

thanks,
scott


>I beleive your problem to isolation in nature. You likely have back voltage
>spikes returning to your outputs and possibly to your inputs. The operation
>of relays and coils involving coils induce a back EMF voltage due to
>collapsing magnetic fields. Best to shunt these voltages to ground through
>the use of diodes. Orient the diodes with the cathode connected to the relay
>output node (relay on) and the anode to ground.
>
>Bruce Wynn
>
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