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Home > Archive > Electrical Engineering > April 2007 > Using 1 Proximity Sensor to Supply 2 Loads
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Using 1 Proximity Sensor to Supply 2 Loads
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| woodglass 2007-04-19, 9:25 am |
| I currently have a piece of equipment that uses 2 NPN proximity
sensors.
Both sensors monitor the same toothed pulley on a machine are used as
inputs to independant counting circuits.
I would like to modify the set up, so that only 1 sensor is used.
The resulting system will look something like the diagram below.
Is there anything commercially available (perhaps from RS Components)
that I can use to provide the 2 isolated outputs for loads A & B, from
a single input fom an NPN sensor ?
TIA,
woodglass
_____________ _________ _________
! NPN ! ! Signal ! ! !
! Sensor !--------! Isolator !--------! Load A !
!____________! !__________! !_________ !
!
!
!
!
_________
!
____________! !
! Load
B !
!
_________!
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| Palindrome 2007-04-19, 9:25 am |
| woodglass wrote:
> I currently have a piece of equipment that uses 2 NPN proximity
> sensors.
> Both sensors monitor the same toothed pulley on a machine are used as
> inputs to independant counting circuits.
>
> I would like to modify the set up, so that only 1 sensor is used.
> The resulting system will look something like the diagram below.
> Is there anything commercially available (perhaps from RS Components)
> that I can use to provide the 2 isolated outputs for loads A & B, from
> a single input fom an NPN sensor ?
>
One technique is to daisy-chain the inputs of two opto-isolators.
It does create the risk of a single point of failure - possibly not too
great a problem if the loads are only counters (and it isn't counting
money ;) )
--
Sue
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| **THE-RFI-EMI-GUY** 2007-04-19, 5:25 pm |
| What about a pair of isolation diodes from the counter inputs to the
collector of the one NPN sensor? This assumes that each counter has its
own internal pull up resistor. And as another poster questioned, perhaps
the redundant sensors are purposeful for data integrity. In other words
if a sensor fails, how do you determine if the process was correct?
woodglass wrote:
>I currently have a piece of equipment that uses 2 NPN proximity
>sensors.
>Both sensors monitor the same toothed pulley on a machine are used as
>inputs to independant counting circuits.
>
>I would like to modify the set up, so that only 1 sensor is used.
>The resulting system will look something like the diagram below.
>Is there anything commercially available (perhaps from RS Components)
>that I can use to provide the 2 isolated outputs for loads A & B, from
>a single input fom an NPN sensor ?
>
>TIA,
>woodglass
>
>
>_____________ _________ _________
>! NPN ! ! Signal ! ! !
>! Sensor !--------! Isolator !--------! Load A !
>!____________! !__________! !_________ !
> !
> !
> !
> !
>_________
> !
>____________! !
> ! Load
>B !
> !
>_________!
>
>
>
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."
"Follow The Money" ;-P
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