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# Current Source Circuit

759 Threads found on edaboard.com: Current Source Circuit

## Constant-Current Source

I understand that we use an NMOS to form a constant current source. My question is, can we create a constant current sink using a similar approach with PMOS? Is constant current sink even a thing? Constant current source is a term used in the circuit theory (...)

## Passive MOSFET bridge rectifier

Are you certain that you wired the actual circuit correctly? You may have the MOSFET body diode voltage drops to account for (2) when current is flowing in RL, e.g. the pin "2" of RL is not actually at ground (potential of the negative plate of the DC source) but diode drop above it). Take a DMM and measure voltage drops around the loop.

## how to make a strong 50hz atmosphere

Are you saying that through this spiral does an electric current pass (ie the wiring is part of some circuit consuming power), or is it just a helical-like antenna ? If you want a 'stable' 50Hz noise source, I would recommend to make some circuit that you could predict the electromagnetic flow and even tune it. An open (...)

## Output PWM'ed audio to speaker

It depends on the loudspeaker and how much power you want. Some NE555 manufacturers specify as much as 200mA sink/source current which is enough to drive a medium to high impedance loudspeaker directly. The mass of the loudspeaker cone will be enough to average the PWM back to an analog level. For higher power all you need to do is ensure enough '

## High current spikes during on and off of the MOSFET switch(PFC circuit)

1-2A peak gate current spikes are normal for power MOSFET drivers (sometimes more, for fat FETs). The Qgg displacement charge has to go somewhere, out the drain, source or both. 'Scope photo is not informative, about what's what. Seems like if you're designing it you ought to be able to tell where the current is from and to, and (...)

## Bandgap reference circuit (bjt area ratio)

Because you are looking to run two equal currents through devices at two unequal current densities. So you need unequal areas. 1:N ratioing is the IC designer's best way to get a maximally consistent ratio. Drawing two different device geometries (like a single 1X emitter, and a single 16X-area emitter) puts you at the mercy of various lithogr

## Current limiting circuit

Hello, I build some project which use a constant power supply of 30V 30A, and i want to limit the current because i'm not use such a huge current and i want to promise that my project will never get 30A in 100%. I want to limit my project circuit current to 1A, what is the easiest way to do it? 136031

## Need help on Rail-to-rail input

The transistors in red boundary are nothing but a simple single stage opamp. The final transistors(common source ones to the right) are used to add the current from the pMOS and nMOS differential inputs.

Hi, As in schematics, the output positive is directly connected, so if it get shorted to chassis or any ground of circuit, the sensing won't even know about it. Correct. But what happens: A short circuit will cause the fud´se to drop. And if it is able to sense it? What schould happen then. It is useless to switch OFF the MOSF

## How to apply external pattern source in mentor graphics tessent tool in DFT domain

Problem Statement:- We are current working on testing of different benchmark circuit using Tessent , DFT Advisor, Fastscan (Mentor Graphics) tool to calculate Test coverage, Fault coverage and ATPG effectiveness, We have calculated above parameters using default ATPG , but we unable to apply external test patterns to improve TC and FC. Whether

## 2 kinds of PMOS current sources

Since you seem to have a semi-infinite series of the most basic questions I think a textbook is right for you. But the textbook isn't going to teach you to recognize, for example, that "Vb" in the lower is the exact same thing as M3:M4 common gate node in the upper, only difference being whether or not the biasing is shown and how complicated i

## Calculating output current in a pseudo current mirror circuit

It looks like an erroneous schematic. Presumed Q1 is a regular NMOSFET as claimed by the schematic symbol, drain and source terminals are interchangeable, and in this case, just drawn wrongly. After fixing the symbol, you get a regular current mirror with an additional resistor R2 draining part of the reference current. Wonder if the (...)

## 7 volt 10 to 20mA variable constant current control circuit for UV LED

The obvious choice will be something like the LM317, but if you don't have one at hand, you can make a very simple current source like the circuit shown below. If you make R1 or R3 variable, you could adjust it between 10 mA and 20 mA. The switch is just for illustration of the minimum and maximum range.

## NO vs NC Relay to reduce seizing

currently have a relay thats rated for 15 amps for a 5amp AC PSU power source (high capacitive inrush current). I have it wired so that its in the NC state, and when the relay is powered it cuts power to the PSU (reason I want it like this is if the relay control logic fails on boot/power on, the AC circuit will still be (...)

## How can we design a simple circuit to tune the slew rate o an ideal square waveform

One way is to use a programmable current source to vary the slew rates as shown below. A lot will depend on required frequency, level, etc.

## max load capability of a voltage source.

If you overload your voltage source and it does not have current limiting then the circuit will smoke and burn or blow a fuse.

## MOSFET Turn-off time adjustment in IR2110 circuit problem

The "problem" is that even if the FET turns off instantly, the rise time of VDS will be determined by its drain source capacitance (Coss) and the load current. If your load is just a 1K resistor, this will result in a fairly slow rise time of VDS. You need to increase the load current greatly to see the true switching times of the FET. (...)

## Commercial products of dual voltage controlled current source in uA level

Even if both currents would be exactly equal, the circuit doesn't generate a "voltage window" rather than a voltage difference V1-V2 with unknown & floating absolute voltage somewhere between 0 and 5 V. I'm not aware of ready made controllable current source ICs in the ?A range. I designed similar (...)

## Drive Mosfet with 5V

hi, A P MOSFET requires negative voltages on the Gate and Drain with respect to the source in order to control source to Drain current conduction. E

## Thermocouple voltage amplifier

Hello! Just a first hint for you. A thermocouple does not deliver a voltage but a current. You should search for a current/voltage conversion circuit. Dora.

## Voltage controlled resistor circuit question

With a series capacitor between the (current source?) and the upper RX terminal, it doesn't look much like a resistor to me. The mentioned photoFET optoisolator is only linear for maybe +/-100mV and then rolls over. Not a good general purpose "resistor" for anything but true small signal (as the datasheet itself makes plain). I wonder about some

## I wonder if it is possible to design a device to debug short-circuits based on ohms.

Finding shorts by measuring voltage drops works quite well with PCBs, except for shorts between continuous overall power and ground planes. You need a constant current respectively current limited voltage supply to source a short circuit current that doesn't damage the board or components. A few 100 mA to (...)

## Using 6 TLP250 how to solve dead time for BLDC motor driver

I presume the TLP cathodes are directly connecting to STM32 IO pins? STM32 GPIOs can basically source or sink the required TLP drive current. But the circuit is completely wrong. - individual series resistors for each optocoupler required, power supply must be 3.3V - high side drivers can't use common power supply, need either three (...)

## LM102 and LM107 replacements

I think the circuit may be from "Op Amp circuit Collection", AN-31, attached is the schematic which uses LM102 and LM107 for a "Bilateral current source."

## What does it means by common mode for a non differential circuit?

It is a differential circuit. The voltage across the shunt tells you the current across the shunt. That's a differential measurement. Common mode refers to the absolute voltage of the shunt with respect to ground. The diagram captures it well. The + and the - are the differential measurements. The voltage source shown is common to both (...)

## Thevenin equivalente question containing control voltages

I now see the reason for the arrow in the current source. It is negative conventional current produced by a current source that must have a negative supply voltage since the base of the NPN transistor is at ground. If the gate of an enhancement N-channel Mosfet is also at ground then the (...)

## Linear circuit with a dependent current source.

Yeah, I forgot the negative sign, because the current k*V1 enters in the negative polarity of the R3. Regards.

## Unwanted circuit coupling between PCA9685 and power line

It could be measurement error. Your scope probe needs to be using tip and barrel only across Vcc and Gnd .... ~ 1cm or less apart without gnd clip. since ESR rises with C, the RC time constant is 10us for LOW ESR and about >>100us for standard. So when cable capacitance is switched current pulse causes a voltage spike at source due to ESR. BIt m

## AC voltage measurement without transformer issue

No AC source is actually floating, and most likely you don't want to operate your circuit directly connected to the mains. A suitable solution for most applications is a high impedance (e.g. 1 Mohm to 10 MOhm) differential voltage divider. It involves some leakage current, but low enough not to trip any RCD protection or to expose (...)

## Vdd and vss are exchanged

Substrate diodes and dedicated protection diodes are forward biased with inverted power supply. If the supply source is able to exceed the maximum diode current, the device is destroyed.

## Transistor input to microcontroller: what uses less current

Check the input high threshold of the micro, the NPN circuit will lose Vbe between input voltage and the output so it may not reach logic 1 anyway. With the top circuit, you might be able to replace it all with a Schottky diode, cathode to the signal source side. For the bottom circuit, consider removing the transistor and (...)

## how to set DC stimulation controller sweep unit accordingly

In the circuit you showed the current source is set to generate a current from 10 uA to 100 uA in 10 uA steps. The setting is given directly in the I source where you have written "IBB uA", so any number you set IBB is in uA. If you prefere, you could also delete uA from the I source (...)

## digital controlled negative current source

Hi, i want to make a digitally(FPGA) controlled negative current source. C1 capacitor is the load. - i want that current change equally for every single bit , for istance 1110 = Ix 1101 = 2Ix 1100 = 3Ix... but in my circuit current doesnt change propartional. i arrange resistor values to make it 2Ix (...)

## how to generate sawtooth wave on GPIO pin?

Some external circuit will be needed - current source loaded to capacitor.

## [moved] Current Mirror design

It's a standard cascode current mirror as described in any analog design text book. Plus two apparently useless transistor sourcing additional current to ground. You would want to review the place where you quoted the image for an explanation.

## MOS intrinsic gain, EE240, test circuit MOSFET with opamp and current source

In first place I thought that this would't work, because you're forcing the current and by definition gm = did / dvgs. If id is constant gm is equal to zero. The same goes for the gds = did / dvds. Even though I tried to simulate that circuit and I get a completly different plot: 129410 The devices I am using are 1.

## [moved] LED control with PWM and Constant current source

I have 6 LEDs in my board connected to the GPIO pins of the MCU. I want to design a circuit for constant current control with supply current in uA(when all LEDs are OFF) The question appears to be incorrect, or perhaps unclear. Are you meaning you want to control the driven current of 6 LEDs in steps of uA's

## noise level of voltage source vs current source

Hi, assume there is a simple connection of an ideal voltage source with a resistor. on the other hand, there is a current source connection with a resistor. I want to measure the resistance in each circuit. now, 1- for measuring resistance of a 10k or higher, it is preferred to use voltage source or (...)

## AC current measurment problem using LTS 25-NP Current Sensor

I use LTS 25-NP current sensor to measure ac current grid. I just built it. I tried to calibrate it using simple circuit consists of a single phase source and high power resistor. The current is flowing when I change the source voltage as appearing in the Ammeter but the output voltage from (...)

## Nuvotone 8 Bit MCU W79E2051

Yes, you cam make your own A/D converter, and it's not too dificult to understand. With a constant current source and a small capacitor, you can generate a saw teeth waveform, which can be used to compare with measured signal. The time elapsed to reach the same value is proportional to the voltage.

## Two poles in oscillator circuit

There's no Vin, gain (transimpedance in this case) is measured with current source I1. Seriously I have no idea how the circuit is intended to work as oscillator, respectively don't know which transimpedance value you want to achieve.

## half bridge series resonant inverter

What is I1? Are you really supplying the DC bus with a current source? That's weird.

## noise file for current source cadence

Hi i want to add noise to the input current source of my multiplier circuit and i want to run the DC analysis. Can anyone tell me can is there any noise file already written that i can obtain from cadence or do it have to write a file of my own and include the txt file. Also once obtained can anyone pls tell me how to include it. In the (...)

## Bandgap refernce design

Hi, All this depends on your circuit. You should give at least your example circuit. * Supply voltage? * output current? source only? or sink too? gain: How much gain do you need? What is the input voltage? I estimate it should be a unity gain buffer, am I right? BW: For me a reference voltage could be considered to be (...)

## output of Parallel RC circuit- Not simple

Ideally, SW3 should not be open, otherwise I current source would generate an "infinite" voltage accross its terminals.

## AC current direction Measuring circuit

To know the inverter power (magnitude and direction), you'll multiply and voltage and current (instantaneous power) and average the product. Under circumstances, it's sufficient to form sign(P) = sign(V) xor sign (I), needs only two comparators. The inverter can also "source" or "sink" reactive power, in this case sign (P) will flicker with doub

## Diode Bridge Rectifier Circuit

Hello , Can someone please explain why the current at the output is considered to a pulse?? I don't understand how this the case if out input voltage is sinusoidal, or is the pulse obtained not necessarily the output? Please refer to the document and the schematic attached htt

## frequency to voltage conversion

for these super low frequencies, use a current source/capacitor ramp generator circuit. Start the ramp at the positive going zero crossing of the input sine wave, and reset the capacitor to 0 Volts at the negative going zero crossing. Save the peak ramp voltage value in a simple diode/hold capacitor and read off the voltage from that hold (...)

## 1ma constant current source for PT100 sensor (Circuit problem

Hello I am making 1ma current source for constant - - - Updated - - - Sorry for mistake Continue......I am making 1ma constant current source for PT100 sensor using OP07 op-amp. I am using a voltage divider for negative pin and a series resistance for positive input pins. At the negative input pin

## Does V/R create current?

Yes the internal resistance will limit the current in addition to any external resistance. Frank