1/1/2024 0 Comments Phototransistor anode cathode![]() ![]() It does not store any personal data.The maximum pulse current that is allowed to flow continuously from the anode to cathode of an LED under a specified temperature, a repetition period, and a pulse width condition. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly. I think his description is better!Īfterthought: You may want to add a diode like a 1N4148 (even a 1N4007 will do) across the OPTEK LED in the opposite polarity to protect the LED against a mistake in wiring. I was writing this while Rick was writing his. They could be completely isolated or have a common ground or be one and the same, as I described above. The supply of the input LED need not be the same as the supply on the output side. The data sheet should give the optimal distance To start out with I would use a highly reflective surface to test, bringing it up close to the OPTEK. If we go for 10mA as well the resistor value is about the same as R1. anode of your desired LED to resistor R2. collector to cathode of your desired LED. If you tried the LED without a resistor R1, then I’m sorry, you’re going to need a new OPB705.Įmitter to supply gnd. (1.6 is the nominal forward voltage across the LED) other side of the resistor,R1 to supply voltage. That should get it working, but you’ll notice that the LED gets brighter and dimmer according to the amount of light that gets reflected into the phototransistor instead of giving a clean on-off indication.Ĭathode to supply gnd. connect the cathode of the LED to the collector of the phototransistor. If you’re eager to see it do something and don’t have a Schmitt trigger on hand, just take a 1K resistor from + supply to the anode of your LED. Connect the collector (and pullup resistor) to one of the inputs, and connect the anode of your LED to an appropriate current limiting resistor and the other side of the resistor to the + supply, and connect the cathode of the LED to the output of the Schmitt trigger. One of the nice things about these is that they are happy with a 5 volt supply or a 12 volt supply. ![]() You could either make one using a comparator or op amp and a few resistors, but the simplest way would be to use a CMOS hex Schmitt trigger, like a CD40106. Now- to connect the LED- since the voltage from the phototransistor is analog and won’t give you a clean 0n-off indication, I’d recommend connecting a Schmitt trigger to clean up the output. If you power it up and connect a multimeter between the emitter and collector of the phototransistor you’ll see the voltage move around as you move objects in it’s field of view. Again, this resistor is not very critical. This rwesistor is not critical as long as you don’t exceed 40mA into the LED.įor the phototransistor sensor, connect the emitter to ground and a pullup resistor between your supply voltage and the collector. If you’re using 12 volts, 380 ohms will be about right. If you’re using a 5 volt supply try about 140 ohms in series with the LED, which will give you about 30 mA. According to the spec sheet it is rated 40mA and has a 1.7 volt forward voltage drop. First, it’s important to limit the current to the LED. ![]()
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