[Emc-users] Encoder supply voltage

[dave]

A few weeks ago when I was having motion problems someone suggested I
check the supply voltage
to the encoder. It turns out to be 4.8 V. The power supply was an 85 w
pico , the little card that plugs
into the 24 pin power connector. Thinking that maybe I could do better
with a standard power supply
I swapped in a 300+ watt supply. Measured the encoder supply voltage and
it is 4.82 V.
System is using 5i20/7i33.
Is that voltage likely to cause problems?
TIA

Dave

[Nicklas Karlsson]

Post by dave
A few weeks ago when I was having motion problems someone suggested I
check the supply voltage
to the encoder. It turns out to be 4.8 V. The power supply was an 85 w
pico , the little card that plugs
into the 24 pin power connector. Thinking that maybe I could do better
with a standard power supply
I swapped in a 300+ watt supply. Measured the encoder supply voltage and
it is 4.82 V.
System is using 5i20/7i33.
Is that voltage likely to cause problems?
TIA

It is supposed to be supplied with 5V, others are common.

[Erik Christiansen]

A few weeks ago when I was having motion problems someone suggested I check
the supply voltage
to the encoder. It turns out to be 4.8 V. The power supply was an 85 w pico
, the little card that plugs
into the 24 pin power connector. Thinking that maybe I could do better with
a standard power supply
I swapped in a 300+ watt supply. Measured the encoder supply voltage and it
is 4.82 V.
System is using 5i20/7i33.
Is that voltage likely to cause problems?
TIA

That is 3.6% low, well within tolerance for all adequately engineered 5v
electronics. But you never know if an encoder might become marginal on
e.g. quadrature prematurely as the voltage diminishes.

If the power supply also has a +12v output, you could hook up a 7805
or similar, with e.g. 330 nF caps to ground directly on input and
output, to provide the 5v for the encoder. It might not even need a
heatsink if the encoder is not too greedy. But measure its output too,
as it may also only put out 4.8v and still be within tolerance. A
schottky diode in the ground leg would in that case up the voltage to
maybe 5.1 - 5.3, still within tolerance, but providing more headroom for
the encoder electronics.

Erik

[dave]

Post by Erik Christiansen

A few weeks ago when I was having motion problems someone suggested I check
the supply voltage
to the encoder. It turns out to be 4.8 V. The power supply was an 85 w pico
, the little card that plugs
into the 24 pin power connector. Thinking that maybe I could do better with
a standard power supply
I swapped in a 300+ watt supply. Measured the encoder supply voltage and it
is 4.82 V.
System is using 5i20/7i33.
Is that voltage likely to cause problems?
TIA

That is 3.6% low, well within tolerance for all adequately engineered 5v
electronics. But you never know if an encoder might become marginal on
e.g. quadrature prematurely as the voltage diminishes.
If the power supply also has a +12v output, you could hook up a 7805
or similar, with e.g. 330 nF caps to ground directly on input and
output, to provide the 5v for the encoder. It might not even need a
heatsink if the encoder is not too greedy. But measure its output too,
as it may also only put out 4.8v and still be within tolerance. A
schottky diode in the ground leg would in that case up the voltage to
maybe 5.1 - 5.3, still within tolerance, but providing more headroom for
the encoder electronics.
Erik

The encoders are Koyo: automation-direct gives the voltage as 5.0 +- .25
so in
theory I should be OK. Just trying to cover all the bases. Next step to
to actually
put a scope on it. All three axes have Koyo's and only the X was giving
problems so
that is probably not the cause. Just a bit paranoid when things don't go
right.

I was rather expecting PCW to weigh in here; no luck so far.


Dave