Electronics > Projects, Designs, and Technical Stuff
Borderlands style jewelry box research thread
Youkai:
I don't think I can do the 3 wire configruation Ian.M because I need to have it connected to Arduino. Does this diagram look correct to you?
EDIT: I'm sure I didn't draw the interaction between the LED and the transistor correct there. Would I just draw that as if it were a wire?
Ian.M:
That should work, (as long as you don't mix up the transistor emitter and collector) active high when the gap is *NOT* blocked.
If you make it active low, by putting the transistor between the Arduino input and Gnd with the 10K resistor as a pullup, you can do three wire.
The usual LED symbol has two parallel arrows to represent light.
Youkai:
I re-drew the diagram. Does that look correct?
I just bend the two pins together and solder one wine to both of them and use that as the ground?
So in this configuration the Arduino pin will read high (5v) through the 10k resistor when the LED is blocked. Then when it's clear it will read low (0v, or close to it) because the path to ground has much lower resistance. Is that correct?
Ian.M:
Nearly - you are missing the arrow that indicates the phototransistor emitter and that its NPN. Assuming you've got te emitter at the bottom, the circuit looks OK.
If you find it difficult to get a good logic '1' level (>4V) when the gap is blocked, due to stray light or an interruptor that isn't totally opaque, decrease the 10K resistor. Don't go below 2K.
Youkai:
Ah, so like this? https://learn.parallax.com/sites/default/files/content/shield/robo_ch6/series_sch.jpg The two arrows outside indicate that it's a phototransistor and the one inside indicates the emitter?
Cool beans. I'll wire up a test circuit with my breadboard tonight if I have time.
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