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1 vote

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 – ...
kruemi's user avatar
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0 votes

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 ...
Kuba hasn't forgotten Monica's user avatar
2 votes

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 ...
Antonio51's user avatar
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1 vote

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 ...
Rohat Kılıç's user avatar
3 votes
Accepted

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 ...
Justme's user avatar
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4 votes
Accepted

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 ...
Simon Fitch's user avatar
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1 vote

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 ...
Simon Fitch's user avatar
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2 votes

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 ...
Simon Fitch's user avatar
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6 votes

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 ...
periblepsis's user avatar
-1 votes

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-...
Dereck's user avatar
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8 votes

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. ...
Justme's user avatar
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2 votes

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 ...
TonyM's user avatar
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2 votes

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 ...
Kuba hasn't forgotten Monica's user avatar
2 votes

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 ...
Hearth's user avatar
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4 votes
Accepted

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 ...
GodJihyo's user avatar
  • 24.7k
2 votes

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)
nanash1's user avatar
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3 votes
Accepted

Please help me identify this IC - top marking "CEK"?

Most probably it is a single 2-input AND gate, SN74LVC1G08DCK in SC70 packaging.
kaosad's user avatar
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0 votes
Accepted

Can anone identify this IC marked `55JT`?

It's a Texas Instruments LM95245 temperature sensor. (Source: aliexpress.com)
nanash1's user avatar
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3 votes
Accepted

Identify IC marking LCSZ

It's an Analog Devices LTC3563EDC step-down converter. (Source: lcsc.com)
nanash1's user avatar
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1 vote

SMD transistor identification

Likely, Transistor is C1815. you can search c1815 smd in google.
sn01's user avatar
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3 votes
Accepted

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 ...
vir's user avatar
  • 20.2k
0 votes

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
Hla Myo's user avatar
2 votes
Accepted

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_{_\...
periblepsis's user avatar
3 votes

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.
Antonio51's user avatar
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0 votes

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 ...
Autistic's user avatar
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2 votes
Accepted

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: ...
periblepsis's user avatar
3 votes

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 ...
Andy aka's user avatar
  • 464k
0 votes

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 ...
Tim Williams's user avatar
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1 vote

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. ...
Justme's user avatar
  • 158k
1 vote

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 ...
periblepsis's user avatar
2 votes
Accepted

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}\$ ...
Dave Tweed's user avatar
  • 175k
0 votes

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 ...
Circuit fantasist's user avatar
4 votes
Accepted

Do transistors "prefer" to pull current from their base or collector?

It would have been instructive to look at V(base) in the first circuit. Then you could compare apples to apples with the second circuit. The problem is not that the transistor "prefers" to ...
Dave Tweed's user avatar
  • 175k
2 votes

Help me to identify an SMD component marked 'NM' in an SOT-89 package

I think @Tony is correct, the photos match lcsc's listing for the 2SCR533P5T100 and 2SCR533PT100. The latter is NRND and the difference between the two appears to be grade related- the electrical and ...
Spehro Pefhany's user avatar
1 vote

What's the role of the transistor on power input in this schematic?

Q1 is a P-channel MOSFET that is normally used in this configuration as a form of reverse polarity protection (for example, if you reverse the cable connection on P1) that is more efficient than a ...
Ronan Paixão's user avatar
3 votes
Accepted

What is the purpose of the diode in this complementary class B amplifier?

The purpose of the diode to reduce the crossover distortion. The diodes make sure that both of the transistors base-emitter voltages to be set for linear operation. This reduces corssover distortion ...
Confused's user avatar
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1 vote

What's the role of the transistor on power input in this schematic?

Q1 is a P-Channel Enhancement MOSFET is open in case your vgs is positive. In this case, you can ensure VIN > GND and protect the circuit from reverse connections.
Jessay's user avatar
  • 21
5 votes
Accepted

What's the role of the transistor on power input in this schematic?

It's to protect against an accidental reversed power connection. Normally, when VIN > Q1_threshold, Q1 will turn on and supply VIN to then'5V' line. Q1 will just act like a negligible resistance. ...
jp314's user avatar
  • 19.3k
2 votes

How to distort a square waveform to get even harmonics?

A 50% duty cycle square wave will have no even harmonics, as you've noticed. Passing the signal through a linear filter will not restore harmonics that are not there, for instance a lowpass filter. ...
Neil_UK's user avatar
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2 votes

Transistor recommendation needed

You want to look for a N-Channel MOSFET that has: As low of Rds-on as possible. This lowers the power dissipation in the MOSFET when it is switched on to as low as possible. Find something with a low ...
Michael Karas's user avatar
1 vote

High side MOSFET driver - transistor design

Some general comments, and some tips to encourage a self-solution. (IMHO: the best questions are those that didn't need to be asked -- because one is equipped to figure them out themselves!) Why are ...
Tim Williams's user avatar
  • 39.1k
0 votes

Guitar pedal mod - trigger button presses from a microcontroller by shorting the switch contacts?

If you want to use an opto you need to know how the button is connected anyway because you have to connect its transistor in correct current direction. Or use two optos with their transistors ...
Michal Podmanický's user avatar
1 vote

Circuit design for a timer and relay

I recommend that you replace the LM2904 op-amps with comparators. (They'll work better, don't risk latch-up in saturation.) Many comparators have open-collector or open-drain outputs and this would ...
Transistor's user avatar
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18 votes
Accepted

Why does 2N2222 allow battery current flow when separate 5V circuit unpowered, but 2N3904 doesn't?

Good chance you've got one of those "2N2222" transistors that has reverse pinout compared to 2N3904 (C-B-E rather than E-B-C). Both kinds are common on the market- there is no standard other ...
Spehro Pefhany's user avatar
6 votes
Accepted

How to identify this IC FG97

It's a SEMTECH SX8652 touchscreen controller.
nanash1's user avatar
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0 votes

How does this gate driver generate 200 V from a 12 V supply?

If the supply voltage is 12V, then the maximum output voltage can only be 12V. Because this is a gate driver, not a boost converter. I don't think this is a mistake of LTSPICE. Because on the website ...
susk's user avatar
  • 51
0 votes

What are the possible disadvantages of using this PNP transistor?

The increased loop length to gate driver is acceptable, because less I and dI/dt flows through it, at least on the falling edge. The driver sinks little current, and what's actually doing the driving ...
Tim Williams's user avatar
  • 39.1k
3 votes
Accepted

How does this gate driver generate 200 V from a 12 V supply?

I don't know exactly what's wrong with this model in LTspice (note that it does not claim to be compatible- "SIMetrix version 8.3g or higher") and I didn't try very hard to make it work, so ...
Spehro Pefhany's user avatar
2 votes

How can I find time constant of a RC circuit with a transistor circuit when switch is closed?

When the switch is closed (conducting) you get \$\tau_{on}=R1\cdot C2\$ When it is open (not conducting) you get \$\tau_{off} = (R1+R2)\cdot C2 \$, ignoring Vbe. Since Vbe << 12V, ignoring Vbe ...
Spehro Pefhany's user avatar
0 votes

How can I find time constant of a RC circuit with a transistor circuit when switch is closed?

By the looks of it you're traing to get a delay for switching off. When you press the button, the LED lights up immediately, when you release the the button, the LED stays lit for some time and than ...
kruemi's user avatar
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