Are you using the relay to reverse the motor?

I have one application exactly like that, but my motor is even heavier,
it consumes 1.2A.
It uses a DIP relay rated for 2A, but I don't allow the relay to switch
while the motor is running., a series connected MOSFET does the current
switching.

Of the seven units in operation for over two years, not even one failed yet=
..


Isaac



Em 09/08/2015 00:21, IVP escreveu:
> Hi all,
>
> I've got 12VDC geared motors here which a client wants to use in
> his product
>
> There are two sizes, both from Shayang Ye
>
> http://www.shayangye.com/english/products.html
>
> The IG420294-25111R and IG520150-40101R
>
> The IG42 is what I'm preparing the PCBs for now, the IG52 is what
> he (might) want to use in the future
>
> The run current of the IG42 is ~0.8A, which the planned relay can
> handle, but the start current does seem quite "sparky" when I test
> with a crocodile clip, and I worry that this may in time weld or pit
> the relay contacts. The IG52 run current is ~1.5A, so its starting
> current will be even higher.
>
> Three options
>
> (1) a heavier relay, although that too may get damaged, and space
> is limited for anything bigger than a 16-pin DIL type
>
> (2) "something" to absorb the starting spark
>
> (3) PWM the motor from 0 to run current
>
> Option (2) would be the most convenient at this stage. What could
> I use ? An RC snubber across the motor and/or relay ?
>
> Option (3) is doable. Product has PIC content with a spare output,
> would mean changes to the PCB and s/w
>
> TIA
>
> Joe
>
>
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