How big of resistor do I need for opto coupler?
The resistor size depends on what you are loading the output side with, as this opto coupler has a “current transfer ratio” (CTR) of .5, so by driving with 20 mA you should be able to drive a 10mA load. When you do this measure the voltage on the output of your Arduino and also where the resistor meets the opto.
Which is an example of an opto-coupler application?
Common applications for opto-couplers include microprocessor input/output switching, DC and AC power control, PC communications, signal isolation and power supply regulation which suffer from current ground loops, etc. The electrical signal being transmitted can be either analogue (linear) or digital (pulses).
What can the slotted optocoupler be used for?
The slotted optocoupler can thus be used in a variety of ‘presence’-detecting applications, including end-of-tape detection, limit switching, and liquid-level detection. FIGURE 3. Slotted optocoupler device. FIGURE 4. Reflective optocoupler.
Which is an example of an optocoupler circuit?
There are many different applications for optocoupler circuits, so there are many different design requirements, but a basic design for an optocoupler providing isolation for example between two circuits, simply involves the choice of appropriate resistor values for the two resistors R1 and R2 shown in Fig. 5.2.1.
Which is the minimum resistor for an optocoupler?
That optocoupler you are using can have 60 mA forward current in the LED, so give it 5 to 10 mA, not 1 mA. 1 mA is also the minimum from the datasheet, and I like to stay away from minimums like that. The value of the pull-up resistor is uncritical.
How to calculate the CTR of a resistor?
According to the data sheet with If=1mA minimum CTR is 34%. Using series resistor of 1.5k at 3.3V gives If= (3.3-1.2) / 1.5k = 1.4mA. The collector is connected to a 30k pull up resistor.
How many milliamps can an optocoupler handle?
Typical optocouplers can handle input and output currents from a few microamps to tens of milliamps. There are many optocouplers on the market and to find the most appropriate for a particular purpose, vendor’s catalogues and manufacturers datasheets should be studied.