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48 Threads found on edaboard.com: Isolation And Resistor
You'll notice that most industry standard SMPS have the reference and error amplifier for voltage or current feedback on the secondary side and are transmitting the error signal with an opto coupler. This way, the accuracy and linearity requirements for the analog isolator are much lower and can be usually (...)
I'd suggest you use a small transformer to get safe isolation. Something out of a junk "wall wart", or if you have an AC-output one, as-is. Apply the output to a resistor divider that centers the voltage within the rails of the uC's digital inputs, through a series resistor that makes the signal rail-rail at the input node, (...)
hi,all now im working on a 4-way power divider without the isolation resistor R,but when simulation it,unfortuately,i get bad results. my question is: 1.the VSWR(S44) and VSWR(S55) of the output side is more than 4.0,i don't know why it is so the impendence of the quarter-wave 70.71ohm? the files as follow:10325
You need isolation for the gate driver signal (e.g. by an optocoupler) and an isolated power supply. Or a level shifting driver designed specifically for the application.
The opamp and microcontroller are both connected directly to the 230VAC which is a deadly danger. isolation is needed. Voltage spikes on the 230VAC will destroy an opamp. An input protection circuit is needed. The input resistor needs to be made to use high voltages.
Interesting observation and question. First we need to determine the voltage on the Neutral pin wrt to your ground. I think it assumed that Neutral is at ground potential but this can vary enormously according to the distribution configuration, local earthing and soil impedance for the ground return impedance. If there is a voltage present o
The capacitor is used as though it was a resistor with equivalent value to it's reactance. In other words, it behaves like a resistor with value of 1/(2*pi*f*C) where f is in Hz and C is in Farads. Beware that this provides NO safety isolation so no part of the circuit should be touchable and that it is (...)
6N137 is not the solution If Ve (pin 7) is low then the output will always be high per the truth table on page 2 of the data sheet. The device is not enabled when Ve is low so this is expected. If you do not need the isolation of a opto a single MOSFET and resistor would be much cheaper. Depending on how the switch is used there may be a (...)
A Fet set up as an amplifier with an accompanying attenuator pad will work ok (maybe 15 dB of isolation), although it might add additional noise or intermodulation products. But since a fet and resistor pad will cost < 1$, and an isolator will cost is an experiment worth running for a production job. Of course, you realize (...)
It depends on how you want to use the 5V. First a warning - if you do not use a transformer you face a serious risk of electrocution. resistor and capacitor votage droppers do not provide any safety isolation barrier, effectively you are connected directly to the 230v AC with all the dangers that implies. If you understand (...)
If you put a stiff gate drive on any FET, the Cgso & Cgdo, and the gate-channel capacitance (which partitions to D, S) all are shunt losses. If you take a hint from CMOS and FET / HEMT RF switches and isolate the gate with a resistor, this is much improved and you are left with the Ron (insertion loss) (...)
Please suggest how to sense AC voltage without isolation transformer by using combination of Resistance and Capacitors. i need to convert AC 230V to a level of 0-5V so that i can sense it using a Microcontroller. I have heard about isolated OP-AMPS are used for that purpose but never used them practically please share your ideas and circuits (...)
PC817 is also good for opto-isolation
Rogers 4350 material should work fine at least up to 10GHz. To get good isolation at high frequencies must have the right terminating impedance at the other port (where you placed a 51 ohms resistor). The 50 ohms load resistor should have minimum parasitic inductance (preferable is to place 3 x 150 ohms SMD resistors in (...)
Hello sir , For 4 way Wilkinson power divider , I used the TFR as isolation resistor, I don't know ,how to find the thickness and width of TFR. I am getting the wrong values for both circuit and EM simulation for S- parameters for S(3,2) and S(1,1).I expect the reults as follows for both (...)
Your input legs are not constant impedance lines. All three legs going into your Wilkinson should be 50 ohm microstrip lines (assumed because you stated you used a 100 ohm load isolation resistor). I'd recommend taking your input lines straight up and down, then go into optimal 90 degree bends, so they are square to the board edge. (...)
have you used isolation resistor? i mean you need to use finally sch simulation for the layout component and place isolator resistor.
Sounds like an every days simulation problem. Possibly the converter simulation don't like zero input voltage. Try with suitable .IC settings. Also the isolation should be bypassed by a mnimal conductance (Mohm resistor).
This is a simple well resistor under STI (Field), the cross section shows an NWell resistor. For better isolation the resistor could sit in another well (for a triple well process). It could also be surrounded by an isolation ring and could have a metal field plate over the top of the (...)
I am in need of signal isolation. The signal is an AC voltage signal of ?200mV amplitude with 230VAC common voltage (line current measurement with shunt resistor). I need to find a transformer in IDUSTRIAL temp range (-40 to +85 C) that is cheap, small (as possible) and can work at 50 Hz. Would anyone know where to look. I wasn't so (...)
If two mirocontrollers either side of a 3.5KV isolation boundary wish to communicate by CNY17-3 optocoupler -what max frequency can they communicate at? CNY17-3 datasheet:
Hi, I am using 8051 for serial communication. It talks with another microcontroller at TTL level. So I think there is no need for MAX232. Am I correct ?. Is it enough if I connect tx of miconA to rx of moconB and rx miconA to tx of miconB. Is it like this or I need to connect some other way?. If I want to isolate this path, how can I do that?. Re
There is the problem with isolation. Enough power could leak from one transmitter to the other to damage the other receiver. I would suggest not doing this.
Hi Simply use 1:1 isolation transformer to isolate the 220V from main and then use the 1:20 resistor divider Also you can use measurement IC like ADE7753 from analog and optocupler to measure voltage and current from 220V rail Please remember to act with caution when using high voltage All (...)
Hi Aloysius, If you dont need more as 1.5KV rms AC isolation & your Iload =< 0.12A than you can apply Opto Mos relay too , their price is only ca. 1/3-1/4 of the Crydoms... K.
you can move the position of resistor and change the length of the 70,7 ohm I would disagree with that. Your isolation will suffer.
you have tied the primar & secondary to ground, so any isolation that the transformer WAS giving you is now gone. maybe this is OK for simulation purposes. otherwise, tie a 100MEG resistor between ground and circuit on the secondary side. what is your guarantee that your primary side will NOT have DC current? do not trust your perfect (...)
Can anybody tell me how to choose the Power Rating of isolation resisters while designing Power Divider?
I have used resistive dividers @ 3 GHz with no problem. Of course you get a losses compared to conventional wilkinson divider. But in case you do not mind burning half of the power in the divider resistors and you don't mind that the isolation between output ports is only 6 dBs, then resistive power divider is most simple solution (...)
None of them would provide you galvanic isolation !! Ground or Vcc are common in all of them. You need to separate grounds and supply.
You can use step down transformer to step down 220vAC to say 12Vac or if you just want to sense the voltage & there is no need of isolation then you can use simple resistor divider.
Total isolation and in the same time dc leakage detection is not possible .. Unfortunatelly, you need a common reference to monitor any leakages or shortcircuits .. One method is to introduce a dc offset (say 10Vdc - now your 0V is 10V and 12V becomes 22V) through a high-ohm resistor (something like 10MΩ) (...)
OD stands for the thin oxide region or active area. STI stands for shallow trench isolation (opposite of OD) In an OD NWELL resistor the resistor is formed in an active area. In the case of an STI NWELL resistor it is formed under the STI oxide. The models for these two (...)
pwoer is conserved so ~7 dB at the output and ~7 dB in the isolation resistor. I would have to dig a bit for the expression. You can have that fun. You might find the answer on the Krytar website. They make the things.
Hi If you for example have a two way wilkinson power splitter, and one output is disconnected. Half of the power is transmitted to one port and the other half is dissipated in the isolation resistor. Regards
Use 150Ω resistor to convert 0-20mA current to 0-3V voltage .. Next, you may use 12-bit (or whatever you need) A/D 3-wire converter such as LTC1288, connect its /CS pin to GND, and use 3 optocouplers to isolate CLK, Din and Dout .. see picture below .. Of course, to provide total isolation between ADC (...)
Most likely you don't have enough current through opto's LED. You should drive it with 10mA. On 5V supply, you should use current limiting resistor of 360Ω and make sure your microcontroller or logic gate output has capability of sourcing 10-15mA. Optocoupler is needed only when you need electrical isolation between MCU (...)
Hello I'm now designing a 5 stages 'cascade' Wilkinson power divider (bandwidth 0.5GHz -6.5 GHz) on RF-60A (Er=6.15, H=1.542mm)according to "A general design formula of multi-section power divider based on singly terminated filter design theory". With the value I calculated according to the specifications in my case, I can have exactly the
It won't have any isolation making it dangerous. It is bound to be as bulky as a transformer option because it will need a high voltage/high ripple current capacitor as the AC dropping element and maybe another high wattage resistor.
HI, Like I remember the resistor (in theory) suppose to be 100 omh, and you need it for improve isolation and return loss of the ports. if you need a formula tell me!! David
It can serve as an isolation for high frequency noise since this O ohms are inductive in nature!
One option is a current transformer .. see details at: This option is safe as it ensures full isolation between the AC line and the output of the current transformer .. Other options can be based on a standard shunt resistor, Hall sensors and so on .. see table below .. In all opt
Yes you can do this but the ISP needs to be sufficiently protected from the application circuitry. You can do this with a D-latch type chip or some other means of isolation.
Try to put shielding on your PIC and ground it properly, it will be also good to have total isolation of your high voltage side to your low voltage side.
For wideband DC bias you can use a wideband choke (lumped or microstrip) in series with a resistor. Both together will get enough isolation between DC and your signal. For decoupling you can use radial stubs or different values of capacitors (with different SRF) in parallel, to cover the entire frequency range.
anyone know how a series 18ohm resistor comes up for the isolation between VDD and the power supply? why not other value?
Does this have to be minimum loss and high isolation? Otherwise a star of 17 ohm resistors will work. Each one connected to an external port.
to measure current there is variety of ways... important parameters are frequency of the current and isolation if you need. in low frequencies you can use ac current transformer or a basic resistor... but hall effect sensors really good solution to measure any current . they can measures high frequency ac currents or dc currents... (...)