On 8/21/22 03:57, andrew beck wrote:
I'm trying to convert these color sensors
US $50.00 | Color Mark Sensor HW-111 Use for Packing Machine voltage 12-24v
DC NPN metal case Photoelectric Eyes Marks
https://a.aliexpress.com/_mtEjRmc
To pnp.
I converted similar sensors with a 10k resistor.
US $2.37 5%OFF | CHUX Proximity Switch NPN M12 non-Flush IM12-4-DNC 5V
6-36v Cylinder NO+NC 4Wires 4mm Detect Distance Motion Approach Sensor
https://a.aliexpress.com/_mLMiQHA
These work fine
My theory was maybe use a higher value one and check with voltmeter
decreasing the value until it works
But I could use a quick lesson from you guys.
So just thought I would ask.
I know a bunch of you.
Chris
Andy
John
And many others
you guys know lots of electronics😊
And so do I, as a C.E.T. And while I did look at the prox switch link
above, I don't have enough data
to expound like an expert.
I do gather that micron accuracy should not be required for this if all
you want to do is verify a pkg
marking or some such with the color sensor.
What I will remind you of is that these things have a time lag AND a
temperature sensitivity, meaning that
the detection distance will vary some with the ambient temp of the device.
This can be a PITA, even a stow-stopper, and I'll give an example here.
Prusa, one of the more expensive small 3d printers, uses a temperature
compensated 8mm
device as the bed level sensor. And you can do 20 copies of something,
1 copy at a time,
and the 20th one will be as good as the first started from a cold machine.
BIQU, with their BX printer, uses a prox senser that looks just like the
Prusa's, but it is not temp
compensated. That printer can do it too, but needs a high speed fan on
it for about a half hour
between each print to get the whole machine down to a consistent
starting temperature. Thats
how much it drifts the first layer thickness. Tolerance for good
adhesion is around .05 mm.
I'm converting an Ender 5+, a huge beast, to use an $8 8mm sensor, if
it works but can't repeat
w/o the extensive shutdown and time wasting cooling, I'll order a couple
of the Prusa spare parts.
At $25 usd, plus shipping from Prague.
Some of these inductive prox sensors run as slow as 150 hz, so their
detection time may affect
you if milliseconds count.
Meaning reliable detection for a part placed to be scanned reliably may
require 100 milliseconds
after the part is placed to be 100% certain it is ready to be scanned.
You may be able to build a faster
machine using an IR photobeam to detect that something is blocking the
beam. Ambient light may
be a problem, so often they switch the IR diode at a good rate, 50
kilohertz or so, then detects
the amplitude of the 50 khz signal, ignoring the essentially dc offset
the ambient light gives.
This type can be pretty dependable and considerably faster than an
inductive prox sensor.
Take care & stay well.
Regards
Andrew
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--
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