It looks very much like a faulty sensor. Contact the shop first: email [email protected] and refer to this thread.
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Ok, so I ordered a new sensor. Performed the same tests, same results!
Shorting still increments the counter, but I canât get the new sensor voltage below 3.5V!
Confused!
So am I!
What did the shop say?
Waiting to hear back.
Waiting tor 23 days? - give them a nudge.
I only got to test the second sensor today! My delay not theirs.
Guys,
even end completing a script that can be run, where a OPS is directly connected to a RPi.
G
Q3 I think would be a P-type transistor.
If it was, it would be called a high side switching circuit, itâd ensure a voltage close to VCC is seen at Pulse during a high input.
You might be right. In which case it is in straight-forward common-emitter (or common-source) configuration.
Iâve changed the drawing.
Right. I recently made a similar circuit. It was in response to getting stuck at using a single transistor to switch up to a higher voltage. Maybe a single logic level mosfet could be used to simplify this circuit. It at least be a matter of getting the right LDR and mosfet working together.
I think a more worthwhile improvement would have the LED on the back telling the truth about the pulse on the output.
And I very much doubt itâs an LDR - it doesnât look like an LDR, itâs labelled âD1â, the encapsulation is a photo-diode, and the response time is likely to be too slow.
I see that. That wouldnât be difficult either.
I havenât used a photo-diode ever. In full forward mode, bright light, theyâd drop 0.7V ? Thatâd look to throw the mosfet idea out, Iâm not sure about 2.6V drop even across a logic mosfet.
Itâd be a case of reading more and experimentingâŚ
DâOh. I just realised that in converting the LED into the sensor, I forgot to turn the diode round. Photo-diodes operate reverse-biased.
So they are!
Just had a brief look at a datasheet. Can see what you mean by speed. Rise and fall time of 5ns in the test. Fast.