Questions tagged [optoelectronics]
Components, circuits, or systems that convert between electrical and optical (light) energy.
279 questions
2 votes
6 answers
329 views
Why there's no limiting resistor at the base of the TIP122 in this device?
I have this circuit of a solenoid controller I have, and I'm trying to understand a few things about it. I simulated it in FALSTAD. I used a relay in place of the solenoid in Falstad. Also two NPN ...
- 661
0 votes
0 answers
39 views
Guidance on prototyping with PPG sensors and pressure cuff systems
I’m working on a project that involves integrating a PPG (photoplethysmography) sensor with a pressure cuff system for measurements on extremities. This is for an academic project, not for clinical or ...
1 vote
1 answer
85 views
Existence of a certain type of optoelectronic device that detects EM waves while allowing them to pass through?
Is there an electronic device that detects EM waves while allowing them to pass through? Kind of like a window that can detect a measure the qualities/quantities of a light ray but lets it pass ...
- 21
6 votes
1 answer
293 views
Linear Optocoupler
I do not understand completely the principle of the linear optocoupler IL300. My reference is this tutorial, especially the part, where it is analyzed in detail: On the left side the OpAmp U1 adjusts ...
- 834
1 vote
1 answer
63 views
Can I connect two SSR devices (TLP3547(TP1,F) to the same load?
I am trying to implement the following schematic: The two +30V sources are controlled simultaneously with the SSR LEDs. So if the top 30V source is switched on, the top SSR turns to ON state, and ...
- 35
0 votes
2 answers
84 views
Correlation between optocoupler "go-no-go" test and CTR measurement
Is it conceivable that during troubleshooting, an optocoupler is functionally OK based on the "go-no-go" test, but when the CTR (current transfer ratio) is measured, the value is outside the ...
1 vote
1 answer
56 views
directly connecting highly doped metals to the active intrensic region in an LED instead of p and n doped semiconductor layers?
Why are p- and n-doped semiconductor layers essential in an LED structure? What would happen if, instead of using these layers to inject carriers into the active region, we directly connected highly ...
- 11
0 votes
0 answers
67 views
LTspice shift a quadratic signal
I need help in a simulation for LTspice. I need to shift a quadratic signal, the thing is that this signal is made in bv (behavioral voltage) using a function; V={V(n_x)^2}, which changes a SINE ...
- 1
0 votes
3 answers
227 views
Why are the optocouplers in this design all connected through a straight line? [closed]
This is a design for a 3-phase H-bridge for a motor driver. I want to know why the optocouplers are all connected with one line in pin 8. EDIT: I think I caused a misunderstanding, this is my design, ...
- 109
1 vote
1 answer
114 views
PiKVM V2 MOSFET relays
I need some IP-KVM's for my homelab, so I decided to build 3 PiKVM's following this guide from the official docs. I almost got all the parts and designed a custom PCB for the ATX controller, which I ...
- 123
0 votes
0 answers
95 views
How can I stop this part oscillating - HFBR-2555AFZ
hopefully I can pose this question well. I have a fiberoptic communications circuit as part of a larger device which I designed which has worked really well with HFBR-2505AZ, but unfortunately I can ...
- 727
8 votes
2 answers
633 views
Photodiode reverse light current question
I am looking at a photodiode BPV10NF and it says the typical reverse light current is 55 μA. In the lab, I have found that the light current keeps increasing with light intensity well past 300 μA when ...
0 votes
2 answers
135 views
Saturating BJT in emitter follower
Can we saturate the BJT in emitter follower configuration by increasing base current? If yes, what happens in the process? How does increase in collector current decrease \$V_{CE}\$ when there is no ...
- 63
5 votes
6 answers
620 views
Emitter Follower - Normal BJT vs Phototransistor
Here is the circuit of normal BJT in emitter follower configuration. I understand that when conducting, $$V_e = V_b - 0.7$$ In the above case, \$V_e = 1.33V\$ Now, consider an opto coupler circuit as ...
- 63
1 vote
0 answers
122 views
Arduino with PC847 optocoupler and WS2812B RGB LED circuit isn't working
I must be doing something dumb here as my circuit tests fine yet I can't control the 5mm LED (not a strip of them). I have a simple 1 second on/off pulse on the input pin 22. I measured pin 16 on the ...
- 11