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135 Threads found on Optocoupler Circuit
Has it already been mentioned that the IGBT driver must provide isolation between the control voltage and the gate circuit? It's a very slow control signal related to usual IGBT application, so anything e.g. a slow optocoupler could be used to isolate the control signal. But you also need an isolated power supply for the gate driver. Can be a sm
Greetings, Does this circuit work well? Application : to control speed of ceiling Fan or to control brightness of a Light bulb. Components : MOC3021 (optocoupler), BTA12 600 (TRIAC) 110117 Thank you !
Hello All, I am trying to drive triac with Positive Power supply. With positive power supply it should be possible to drive triac in Q1 and Q4. Here is the circuit I am using. But triac is not triggering. I have checked in oscilloscope the signal on gate looks good enough. 110099 I really need your expert
optocoupler solution from EDN:
Hello, I have a circuit and I am trying to find its problem. I have square pulses at the tlp250 input (pin3, 5 V peak-to-peak) but I have no output at all (pins 6 and 7 of TLP250). There are six TLP250 to drive the BSM10GN60 IGBT module. Three of them has their Vcc connected together but the other three Vcc are not connected together and are sep
Hi, here is no mention of it in the datasheet. Look at the section "Absolute maximum rating". I bet it is mentioned. To the circuit. It would be helpful to show us... Is the second line of the AC connected to your expander device gnd? You are aware of the risk of electrical shock? I reccomend to use an optocoupler to get galvani
It does seem like there would be no use for a optocoupler with a common ground. Sometimes they are used when someone wants "isolation" not realizing that such a connection does not achieve the desired result. Can you post the circuit?
Short answer: no. 5V (less the LED drop) across 100K would only give you about 30 microamps. Unless you have an optocoupler that can work with this low current, you'll need to find another method. I'm not sure what you mean by "My scope is need to check the voltages". If you are using a scope, what do you need optos and rectifiers for?
I think the optocoupler cannot source the current required by the lamp. what type of lamp you are per the optocoupler datasheet, only it can source 10mA current. Try replacing the lamp with a LED to verify your current demand.
Is there any optocoupler ,which can be used for isolating analog signal?
The only thing a zener and an optocoupler have in common is that they both have "er" in them. Why do you have a zener in your circuit? Why do you have that other diode? Why do you have two 10Ks in series with that zener that you don't need? What is it you actually are trying to accomplish?
hello, will this ckt work?? R1=R2=22k 2 watt.. whether it will blow the optocoupler ?? please help... . Reverse diode is usually not included into the photocoupler and must be added.. this could be work ... without transform this output as DC average... I suppose you will send the square 50Hz signal in
I fear, the problem isn't clearly specified. What do you exactly mean with "protect the microcontroller"? In many designs, isolation between control circuit (e.g. microcprocessor) and DC bus is required. Of course, isolation involves protection against damage by a defective power stage, but that's not it's primary purpose. If the control cir
Last year for Christmas I did chaser circuit with AT89C4051+bc547+BT136, it was not recommended by this forum, (I was warned against bringing MC in contact with mains supply) was told to use an optocoupler. It just worked and was not perfect. And now - For using opto, as a prelim, I used PC817 separately , I connected it to 5v supply using 560
Are you aware of the huge signal delays caused by the optocouplers? Depending on the intended switching frequency, fast logic optocouplers might be required.
Dear Members, I am designing 2 KVa pure sine wave inverter system , using SG3525 to step up 24 Dc to 320 Dc , and then using IR2110 to make pure sine wave by SPWM signals from pic16f684 . I have a question that should I Use any optocoupler (like tlp250) between Microcontroller and Driving circuit or should I give signal directly to IR2110. (plz su
hi all. im trying to simulate this voltage sensing circuit for the output voltage of a boost converter. its an LM358 + an IL300 linear speaking the circuit seems to work fine in all the range of my output voltage the only issue i have is that for a voltage >~ 280V
I am using pulse train to trigger TRIAC and using moc3021 optocoupler to trigger triac ...circuit is working with frequencies up to 30Hz but i want to work with 50Hz/230V but it is not working....please chek circuit...and help me...please friends.. waiting for your replies 8-) 96659
You could, I expect, use the optocoupler as an emitter follower and avoid saturation. Provided that the pin receiving the follower output is happy with a somewhat reduced output voltage. If you trigger on the turning-on edge, and your frequency & min-off-time of the coupler is low enough to let saturation recovery tun its course, then fine. Trig
Hi there, I am successfully using the attached ECG circuit to get ECG signal. The problem is that this circuit needs two separate 9V DC batteries - one for the amplifier circuit & other for the isolation circuit (which has an optocoupler). This safety feature is great when one is physically (...)
what do u mean by fetch data...... use optocoupler with 220k resistor for each phase having star configuration
The circuit doesn't seem to make sense. Why you are using an optocoupler? Obviously there's no isolation problem. The circuit however suggests that the problem is about an unmodulated IR "beam". It will in fact suffer from ambient light, direct sunlight is the worst case. Optics is most likely required to make it work. Most optical (...)
The input is a high voltage pulse signal, I would like convert it into TTL signal so the microcontroller can capture the pulse width. I use optocoupler to isolated the the high voltage signal.
the dimmer circuit I'm using uses a potentiometer so I just need something to operate the potentiometer from a distant Whether u r ready to replace POT with optocoupler? or u wanted to operate the POT with a motor setup? How many steps brightness control u want? RF or IR/LASER? (RF is better) micro controller based or without u
hi all i want to know how make a solid relay state i tried to use mosfet irf730 to control as switch 12 vdc max 10 amp . drive microcontroller and optocoupler but mosfet heated i want help to make a solid rely and the circuit. thanks . Hi fawzy73 To design a solid state relay you need to use combination of one P mos and one N mos
thanks. someone protecting port with optocoupler. why we must isolation with optocoupler?
@pplus can u tell what u mean by Vka? is the cathode voltage of tl431 or that of the optocoupler? thanks
Do you want to test the optocoupler or the FET? And is this an in-circuit detection, or do you want to check components on the bench?
Hello, This is a really big problem in using triac for switching AC devices using microcontroller and optocoupler.I made a circuit which uses optocoupler MOC3041 and triac BTA16-600BWG.Due to the minor delay in switching of Triac there is a jitter at the zero crossing of the signal.This has resulted in burning of coil in my lower quality (...)
Actually there is '-' ,'+', and comp terminals for sg3524 pwm controller.. i m designing isolated converter for our application. i need to isolate the voltage sensing which is given to '-' terminal of the error amplifier.. how to acheive it..? any idea or example circuit..? Usually i used to go with tl431 and optocoupler at the feedback side to
is it possible to give 230v ac input directly to any optocoupler
Hi scmojks As i can see , the circuit has a big problem ! when optocoupler is on , the transistor can be destructed because you don't have any resistor in BE diode , path . Best Wishes Goldsmith
How to identify resistor and capacitor values in optocoupler feedback circuit? componet involved:optocoupler,AS431,resistors and capacitors..Please help..
I am looking for a very high isolation between two microwave circuits(4GHz)(isolation > 50dB). Is it possible to use a optocoupler between these two circuits? What should be the specs and type of optocoupler, i should use? Kindly help by sending some details on such a application. thanks
I'm designing a circuit with optocoupler 4N25 and 24v dc input which output is connected to the microcontroller Please calculate the resistance R1=? R2=?
interrupt pin RB0 to optocoupler output
If you better look in optocoupler, inside on one side is transistor with optical control of his base. If you need small size you can use some adequate ratings SMD SOT-23 transistor and his base control by adjusted input signal which you use on LED side of optocoupler. But you should know that then you dont have isolation of circuit For (...)
Hi I need circuit 24v dc to 5 v dc for digital input plc .I want use optocoupler TL21 Please help me. I want an input module with 24 volts to optocoupler, when the output voltage is 5 volts optocoupler be active in micro be used for input input 24v dc optocoupler TL21 OUTPUT 5V DV T0 INPUT (...)
Use optocoupler for that, dont put any additional load on ignition contact lock. You dont even need ignition lock, You can make circuit which will sens difference between turned off engine 12V-12,73V and when engine is on 13,8V-14,2V from lighter plug or similar.
Hi I m working on a circuit which need to drive an optocoupler(4n35) using a micro controller. The problem is when i connect the uc with the optocoupler the low logic pin of the controller rise upto say 2.26V. I have checked the datasheet of the at89s52(micro contoller i m using) it says the pin can sink a max of 10 mA so i added (...)
Are you trying to drive the FETs directly with the optocoupler, or are the optocouplers driving other gate drive ICs? You should post the actual gate drive schematic. Insufficient current in the isolators can cause several problems. Of most concern is the possibility that the turn off time of each FET will be increased greatly, leading to cross
Will my circuit connection work? At default state, the MCU pin is at state 0. If the MCU pin changes state to 1 it activates the 12v solenoid. Does the optocoupler make any difference if it is there or not? 69608 maybe you should add a pullup resistor 10k on pin colector opto
Hi all, I have a H-bridge circuit which is 1500W and operating at 25khz pwm. The power line is 230V. The logic circuit controlling the pwm is 5V. The 230V to 8V transformer supplies the 5V voltage regulator. The logic circuit and high power circuit is isolated with optocoupler. Although there is an EMI (...)
I designed a circuit to drive a load.i used two supply(Vcc=5). Is the circuit that I have designed correct or not? Is there any another design to drive a device else using relay(I don't want use Relay). tnx
Use this : 64382 In your case use second circuit. tpetar dear .tank you for circuit.but in this circuit output become off when optocoupler become off.i want to output has became on when opto coupler become on only one time. :roll:
Hello everyone I have a RS485 based relay control hardware. I need to transfer a ground signal to a remote component. Once the component is on (by receiving my ground signal), it sends a back indication in form of ground signal which is received at AT89C51. I have isolated the ground sent/received to/from the component using optocouplers. I need
Your quest is about switching AC .. For that you need a triac driven by, for example, an optocoupler .. Have a look at the attached picture .. circuits like that should work ok with voltages down to roughly 12Vac . :wink: IanP
Dont worry I will help You. ---------- Post added at 21:18 ---------- Previous post was at 20:13 ---------- I suggest You that for switch use optocoupler with some mosfet as switch (turn On when sense current in monitor). Look this circuit examples may be useful: Web location : [url=www.e
Hi, I'm using the optocoupler HCNR200 and I need to know how I can to use it for measurement 220 VAC, because I'm probing the circuit dual with two LM158 and two HCNR200, but the circuit not working. (The circuit that I use is of the figure 3 of the application note 1357 of Agilent technologies) If you can help me, (...)
If I keep the power pad of HCPL-0708 to ground, what is the output level when I toggle the input from high to low ? Many thanks.