New answers tagged transistors
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How is junction-to-ambient temperature measured?
There are a bunch of assumptions, often not stated or hard to find. For example, with diodes they may make assumptions about lead length, copper pads and type of board. The loss down the leads can be ...
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Transistor switching speed
I won't go further than a very simplified (1st order) model of what's going on to help develop a meaning for \$f_t\$. There are higher order models. But to a first order the following approximation ...
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Transistor switching speed
Switching speed of transistor cannot be defined with exact number.
For high efficiency SMPS design you don’t want the transistor to be in linear region more than example 2% of overall time.
On other ...
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Help with circuit analysis - Transistor, dc-motor, arduino, resistors
Let me draw your circuit with some annotations that I can refer to later:
simulate this circuit – Schematic created using CircuitLab
Your equation for \$R_B\$ was calculated as follows:
$$ R_B =...
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Diagnosis and Replacement of 2N1101 transistor
Your understanding is not correct. With a diode tester a bipolar transistor should show around 0.6 V for silicon, 0.3 V for germanium from both the collector and emitter to the base, depending on ...
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Help with circuit analysis - Transistor, dc-motor, arduino, resistors
To avoid burning resistor or transistor, use constant current buck converter IC to generate the required current. But, my advice is - don't make your life difficult; check the specification of the ...
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Help with circuit analysis - Transistor, dc-motor, arduino, resistors
To start with, your formula for \$R_B\$ is incorrect if you're using an emitter resistor. You have to take the voltage drop across that resistor into consideration. But then you don't really need the ...
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Import transistor into LTSpice
Similar question has been answered here.
You encountered an error because of a missing dot before the SUBCKT. I have corrected it in the script below. Save it in a ...
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Finding relationship between saturation current and Vgs for MOSFET?
There's never a guarantee that a certain amount of current will flow, given some particular \$V_{GS}\$, because it varies so much even between devices from the same batch. Even if a datasheet does ...
- 38.9k
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Switching ON/OFF an ADC line
Well, there's a couple possibilities:
Don't care. If the input currents are small enough, there's no wear on the ESD clamp diodes*, and VCC lifts imperceptibly against the normal loads on it (MCU ...
- 39.6k
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Switching ON/OFF an ADC line
which electronic component could one use to switch ON/OFF several
external lines for ADC?
Analog switches and multiplexers come to mind, most designs have two parallel mosfets, one pmos and one nmos ...
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4N25 Optocoupler design
You have a wee bit of an issue with a 100Ω load and this circuit. Generally you'd like the base current of the transistor Q2 to be 1/10 to 1/20 of the collector current, which argues for an R6 of ...
- 407k
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4N25 Optocoupler design
Indeed. You want to give yourself a good margin relative to the maximum current defined by the CTR, because this will decline as the device ages. You want the 4N25 output transistor to be saturated ...
- 175k
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Why does this transistor amplifier fail if Rc is greater than 50 ohms?
I wonder about accurate simulation of RF, using your current understanding of bipolar circuits. But I'll drop that and move on.
A couple of bad things done in that ...
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Is my setup for a 5V motor project faulty?
You have the transistor "upside down." It should be like this:
simulate this circuit – Schematic created using CircuitLab
The arrow in the transistor symbol points towards ground. ...
- 72.5k
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Will this 3.3 V signal voltage be high enough to close Q3?
Q3 is a darlington pair, meaning that you require \$V_{BE}\approx 2\times0.7V = 1.4V\$ to switch it on. A potential of +3.3V at PWR_ENABLE will be adequate in this application, because collector ...
- 38.9k
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Will this 3.3 V signal voltage be high enough to close Q3?
(Your current question title says 3.3 V while the text says 3 V, so I'll use the lower of the two.)
Driving PWR_ENABLE with 3 V will be plenty to switch the whole ...
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How do you separate a logic gate from the circuit implementing that logic gate?
The way transistor biasing works, it isn’t really possible to make an AND or OR gate without the additional inverter stage.
- 55k
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Transistor AND gate problem
What you created is an NAND with an open collector output. The Output would be at the collector of the upper transistor and the LED will light up when the output is low.
simulate this circuit – ...
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How do I analyze an emitter follower with a capacitive load?
how can I predict the emitter voltage or current?
Generally, you'd do it by solving the differential equation system that models the circuit. SPICE does it numerically. You may be able to come up ...
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Power dissipation in an IC
Made with microcap v12.
For this task, you could use the file "uA741.cir" included with microcap.
Microcap calculates the full powers by "definition".
Here, it should be 72 mW ...
- 14.5k
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Power dissipation in an IC
What is the correct method to calculate power dissipation in the circuit which means power dissipated in all BJTs?
Assume no load is connected and no input signal is applied to either inputs, and ...
- 36k
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Power dissipation in an IC
Think of the opamp as load like a simple resistor.
The power dissipation of any load is defined by the voltage over the load and current through it.
With +/- 15V supplies there is 30V over the load so ...
- 159k
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How do I analyze an emitter follower with a capacitive load?
Since the transistor is only able to source current from the positive supply, implying current flowing downwards through the capacitor, and since you've provided no way for current to flow upwards ...
- 38.9k
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Simple BJT circuit problem
The schematic does not explicitly specify the potential of the lower node, and you are correct to question this. You are also probably correct that the author intended this to be 0V.
For the PNP ...
- 38.9k
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Why is a push-pull transistor configuration asymmetric?
Each transistor is responsible for passing current in two different parts of the input/output waveform, between which current in the load changes direction.
The upper transistor is allowing current to ...
- 38.9k
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Why is a push-pull transistor configuration asymmetric?
Everyone has already pointed out that one of your transistors is arranged incorrectly. So I won't belabor it here. Sufficient that you know it won't work.
The phrase ...
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Why is a push-pull transistor configuration asymmetric?
Your circuit is invalid. Try something like this. It can operate from a single-ended power supply. Reference the amp to 6-volts. Circuit reference https://circuitdigest.com/electronic-circuits/push-...
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Why is a push-pull transistor configuration asymmetric?
But that's not a valid push-pull circuit to begin with.
You have the PNP transistor upside down.
Even if it were correct, for negative output you would need a negative supply and you don't have one.
...
- 159k
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Simple BJT circuit problem
Is the problem missing some vital information?
Yes, very much, as you note yourself. It is missing:
Ground connection. This is reasonably assumed to be the horizontal at the bottom.
Transistor ...
- 23.6k
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Simple BJT circuit problem
The inclusion of the switch also seems weird to me, as its purpose isn't relevant to this practice problem.
Re-reading the problem statement: The 5Ω heater in Fig. P-1.6 is to be turned on by closing ...
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How do I analyze an emitter follower with a capacitive load?
The problem is that you're trying to linearize about a DC bias where the transistor is deep into cutoff, because there's no way for C2 to discharge. The emitter voltage is pinned to Vcc, and you're ...
- 35.2k
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Simple BJT circuit problem
The ground is the line at the bottom common to the switch and heater resistance, they just didn't mark it as such.
The switch is relevant, it is the thermostat switch as mentioned in the problem. It ...
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Identify board components Yaskawa Z1000 VFD
The component on top is a 10 kΩ resistor. The one on the bottom is a SMBJ17CA TVS diode made by Diodes Inc.
(Source: lcsc.com)
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Please help me identify this IC - top marking "CEK"?
Most probably it is a single 2-input AND gate, SN74LVC1G08DCK in SC70 packaging.
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Can anone identify this IC marked `55JT`?
It's a Texas Instruments LM95245 temperature sensor.
(Source: aliexpress.com)
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Identify IC marking LCSZ
It's an Analog Devices LTC3563EDC step-down converter.
(Source: lcsc.com)
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Why do I have to increase the current by 2V when I am using a transistor?
It is dim because the collector-emitter saturation voltage for your transistor is ~2V. Use a logic level MOSFET and a current limiting resistor. You won't be able to get full brightness with a 3V ...
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Can anybody help me identify this SMD component?
Looks like pmv65xv in 12/24 power supply. I have the same problem in TLC and i have the blue print of the circuit
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Why do some JFETs oscillate and others don't?
models and datasheets
The MMBF4416A datasheet you provided is terrible. There are no charts given. Nothing to examine. However, my eye is drawn to this:
If you now set this up in LTspice where \$V_{_\...
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Why do some JFETs oscillate and others don't?
Made with microcap v12, interactive mode "Stability" analysis.
Just change your C1. It will start to oscillate within 250 us ...
Tried until 420 MHz.
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Why do some JFETs oscillate and others don't?
JFETs have very spready DC characteristics .I have not used them in any high volume products due to fear of a production disaster. Sure people do and seem to get away with it .Try reducing R1 to get ...
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Solving complex opamp circuits
I've grabbed up the part you seem to be asking about and labeled an additional node.
I'll be using SageMath/SymPy for the symbolic KCL analysis. It flows about like this:
...
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Solving complex opamp circuits
It's called an MFB band-pass filter and is well-known in the industry. Here are a few references that get you started on what it's all about.
Ref 1 from ESP
Ref 2 from MT-218
Ref 3 from eCircuit
I'm ...
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Which characteristic of a BJT determines the timing in the following given application?
Stored charge and saturation.
Namely, the transit time parameters. TF is forward transit time, for the common-emitter case; TR ...
- 39.6k
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Designing a 24 V output relay using PCF8575
You are not telling how exactly you are connecting the optoisolator LED input to the IO expander.
Since it does not work, it is a safe guess that you connected the anode to IO pin and cathode to GND.
...
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How much current will a BJT transistor draw through its base?
There are two primary viewpoints for the BJT: the DC operating point and the AC behavior around that DC operating point. You must keep these ideas totally separate in your mind. The connection between ...
- 11.2k
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How much current will a BJT transistor draw through its base?
Shouldn't \$i_B\$ be the full current we'd get between base and emitter if we simply had a diode? If it's not, then how do we predict what \$i_B\$ is?
It is.
But you need to remember that \$V_{BE}\$ ...
- 175k
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How much current will a BJT transistor draw through its base?
The transistor will draw more current from the base if you disconnect its collector.
Yes, the BE junction behaves like a diode but here its cathode follows the anode, so the current is too small.
You ...
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