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I am pulsing the VDD with 50% duty cycle at a frequency of 188 Hz (PWM). I get some weird spikes on my output TP3. Am I missing something about phototransistors?

Here is the picture of the IR circuit and the output from TP3: enter image description here

Here is the circuit of the PWM output and how it looks: enter image description here

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  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$ – Dave Tweed Jun 6 '17 at 19:35
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I think that its not a spike, and because it is a photo transistor. The transistor is slow, after a spike, the photo transistor lowers the voltage/current. It is recommended to use a laser, just use a mosfet. Then connect it to a laser, and on the output, just put an led, right into a common transistor, (you might need an op amp to amplify the led signal)

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