Reply to "IR or Optical Sensors"

stan2004OGR Forum Member

ken's trains posted:
Don't want to be lazy so looked up NPN operation. If I understand, when beam is detected, most current flows to GRD through sensor. Therefore, transistor is off and emitter would be floating. So maybe a resistor from E to GRD would solve problem?

Correct. When beam is detected, NPN is off, emitter is "floating" so a resistor from E to GRD would solve the problem In this case you should use the regular pinMode (x, INPUT) instead of INPUT_PULLUP. Someone correct me if I'm wrong, but there is no Arduino that supports pinMode (x, INPUT_PULLDOWN).

I realize the NPN circuit is all wired up, but couldn't you just run a jumper wire as shown in purple above? It's OK to leave the NPN as-is with the E disconnected.

Attachments

Hide

Images (1)

3/19/203:35 AM

<ul id="{%=id%}ButtonGroup" class="button-group h-popup-buttons even-button-group even-1">
    <li id="{%=id%}Okay_buttonContainer"><a id="{%=id%}Okay" href="javascript:void(0);" class="button success no-margin-bottom h-alert-modal-ok-button" role="button">OK</a><script type="text/javascript">
        (function() {
            function {%=id%}Okay_click(event, data) {
            {%=id%}Popup.hide();
        }
        
                $('#{%=id%}Okay').on('click', {%=id%}Okay_click);
        })();
    </script></li></ul><a href="javascript:void(0);" class="close-reveal-modal" aria-label="Close Modal">&#215;</a><div class="last-modal-focus focus-utility-element" tabindex="0"></div>
</div>
<script type="text/javascript">
        (function() {
            {%=id%}Popup = new SS.Popup.ModalPopup('{%=id%}');
        })();
    </script>

Skip to main content

Attachments

Membership Required

Remove From Your Block List

Manage Follow Preferences

Block

OGR Forum Supporting Membership Required

OGR Forum Supporting Membership

Help support this forum with an OGR Forum Supporting Membership.You will be able to watch the videos in the INSTRUCTIONAL VIDEO FORUM!A one-year OGR Forum Supporting Membership is only $12 per year, so sign up now!

OR

Access the ALL the OGR VIDEO FORUMS AND over 300 back issues of OGRwith a DIGITAL SUBSCRIPTION!

Please wait...

Help support this forum with an OGR Forum Supporting Membership.
You will be able to watch the videos in the INSTRUCTIONAL VIDEO FORUM!
A one-year OGR Forum Supporting Membership is only $12 per year, so sign up now!

Access the ALL the OGR VIDEO FORUMS AND over 300 back issues of OGR
with a DIGITAL SUBSCRIPTION!