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92 Threads found on Transistor Hfe
I'm trouble-shooting a pre-amp from a 70's Fender Rhodes electric piano. Pretty simple device... but I realized that I should poke around to see what equivalent transistors I might need. With rare exception, the designer selected 2N3392s for his go-to transistor. Amplification, buffering, tone controls... all 2N3392s. The top rail is 25 V, sing
IV curves cannot be used because the hfe of any transistor part number and the base-emitter voltage are a range because some of the transistors are more sensitive and others are less sensitive. The curves on a datasheet and a simulation show only a "typical" device but the circuit you design must have enough negative feedback so that it (...)
Dear friends. I wanna make a fm transmitter with electret microphone for my elder aunt. We all live in same apartment, and sometimes my elder aunt need help. If we can listen her by our FM radio, when she need help, we can immediately go and help her. It was my main aim. So I researched some circuit and I found one of them that seems solve my
KSC388 (npn transistor) datasheet page 2 says it has a hfe of 20 to 200 However, graph on page 3 (fig2) shows its hfe is around 110 to 150. Which page is right? KSC388 NPN datasheet
Hello, Can someone please explain how to go about choosing the collector resistors for this topology? Say i want frequency of 500 Hz, then i know that : If i let C1=C2=0.1uF then i find that R1=R4=14.5k will provide the needed frequency For some reason i dont know how to Choose R2=R3 If VCC=5V and VCE=0.3 V (to ensure im in the active
It's pointless to compare audio low noise with RF transistors. Unfortunately you didn't even mention the frequency range of interest, particularly does the noise corner frequency matter?
No problemo, sorry I took it the wrong way. I think I just need to look for a cheap switching TO-3 NPN transistor , maybe 250V or higher with about 10A capability. I'm going to try a BUX32B. Try if you like but it has poor gain and Rce hfe= 8 ~40 @ 3.0/6.0 (Vce / Ic ) implies Rce= 500 millOhm 8 is low
Hi, I'm using the 2SB507 as a regulator bypass transistor, and have a small concern about the specific two I am testing the circuit with which I wanted to use: A few months ago, the same type of transistor (perhaps even the same batch, they came in the same bag of 10) had a fully on voltage drop of 0.65 - 0.7V, and a guesstimated hfe (...)
One other thing, notice they haven't quoted a quiescent current? When I have one connected to a circuit it drains the battery when left idle, that's why I decided to toggle the power using the transistors. Before making things complicated, try measuring the current again with the DATA pin tied to ground, my experience of these kinds
Hi, I need to replace a broken transistor, is a BFR36, but I'm unable to find the same transistor at the local electric shop; I can't exactly figure out which equivalent would be ok: by a search on Google I've seen a pair of possible candidates: 2N5109 and 2SC1068; which of these two would be fine? Or maybe someone could suggest me a good altern
Simply look at the datasheet of the switching transistor. Here is a little 2N3904 transistor switching a 50mA current and a big 2N3055 power transistor switching a 10A current:
A transistor in a TO-220 case is usually used at 1A to 3A, not at just 0.0025A like your tester uses. hfe is not used when the transistor is a saturated switch anyway, usually the base current is 1/10th the collector current for a switching transistor but at higher currents the base current might need to be 1/3rd the (...)
Aren't the output transistors a complementary NPN and PNP pair of emitter-followers? Then if the NPN is cutoff with a Vce of 69V the PNP is saturated with a Vce of close to 0V or close to the negative supply voltage, not 38V. hfe does not matter if the driver transistor can supply the maximum base current needed for the output (...)
You NEVER EVER make a common-emitter amplifier like that. The base current for one transistor part number has a wide range (the hfe value) so some transistors will be saturated (high hfe) and other transistors will be cutoff (low hfe). Negative feedback is needed to effectively reduce the (...)
Hi, In linear power supplies there is a transistor (usually darlington) that is current-controlled depending on the output voltage. The problem is I cant seem to find the Vout - current-to-darlington-base equation. Do I operate it in the linear region? When Vout < Vout_desired do I saturate it? What is the range of current in its base? (i
Darlington's have the disadvantage of almost 2 diode drops initially ( actually 1 diode drop & 1 saturation drop) but when conducting heavy currents with fast pulses in PWM due to low input capacitance compared to MOSFETS will have better current gain( ~100) . When the transistor is used as a switch and saturates, the hfe typically reduces to o
How can I simulate a circuit using 2SC1969 transistor in ADS? i don't think there exists a model of 2SC1969. So how can I simulate?
Your emitter capacitor C1 shorts the emitter resistor which kills all AC negative feedback. Why is the DC collector voltage so high that the transistor is almost cutoff? I simulated it and got a voltage gain of only 30.1 times. I corrected the bias so that the DC collector voltage is 6.3V and got a voltage gain of 181.3 times. Without any negativ
There is a different class of transistor switch with ultralow Vce and Rce with higher hfe and gain at saturation. I wont get into the epitaxial differences but instead of 10:1 Ic:Ib specs for switch operation they are 50:1 and usually specialized by Diodes Inc and some others. They also class the devices for NPN with Rce like MOSFETs
I'm searching for another pair of transistors but all i find with suitable voltage/current ratings have approximately the same hfe. There is something I don't understand and are missing, but what? When designing power supplies with discrete transistors, you should also consider other circuits than single (...)
The capacitance of a transistor and its wiring is a filter and produces negative feedback from the collector to its base due to the Miller effect which reduces the hfe AC small signal current gain. The hfe DC small signal current gain is not affected so it is the highest. Fairchild's datasheet for the 2N3904 transistor (...)
Friends I am new in RF design. I want to design a class A power amplifier at 850 MHz by ADS. How to calculate Zin and Zout of transistor Q2SC5761_M16 for input and output matching network. hfe of transistor Q2SC5761_M16 and QN3440 are 300 & 100 respectively. Graph of Vce Vs ic is correct but graphs of Zin and Zout are wrong. 10
If I remember my transistor circuits, the output impedance of a common-collector transistor is the emitter resistor (100K, in your case) in parallel with (input impedance)/hfe. Thus, you're still going to have a pretty high output impedance (maybe around 50K). Can you use a lower value emitter resistor?
Question is pure theoretical. Input impedance equation should be solved using four-pole parameters of transistor. Expression is needed and not numerical result.
BC 546/7/8 is one of the most used general purpose transistors, so don't worry about availability. If you want that any BC548 type can be used (A, B or C), calculate the resistor for the A version. If you can have some power consumption from 3.3V, just go for 1 mA, this will sure saturate the transistor. At low temperatures hfe drops and (...)
I applaud your decision in "going all the way" and designing a discrete-component amplifier. It is a good learning experience! :idea: But my first word of advice is that you'll definitively need more than a DMM to design and debug it. Beg, borrow or steal an oscilloscope and a function generator. Also, some power resistors, because if you plan on
Well, I'm not sure I'd say it this most important thing to know... There are a number of things you need to consider in selecting the transistor, in no particular order: What voltage will it operate at? What is your current load? What is the available drive current and voltage? How fast do you need to switch your load? As far as hfe, a rule of th
The 0.1 miiliohm value you put in for R8 isn't but ridiculous. Sorry you could not grasp that R8 with its value was not a working part. It was a placeholder for the sim and to help explain what I am asking about. All in all the problem can be easily solved and has been already a thousand times.[/
Hi, Can anyone point to me a equivalent transistor to the 2DC 5609? Thanks, Bruno
I have a heavy load to drive with a PIC and I want to use an NPN transitor with load on Collector. I'm looking for a transistor that starts conducting with a very low current on base, low enough to be driven with a PIC (TTL out, 25mA max). I also need high current on Collector (around 1A). To better explain the way I'm going to use it, here's the
Hello I have this simple current source circuit and the current source through the collector is controlled by voltage drop across the transistor base emitter and resistor R5 Ic=Ie = Vbe/R5 but i want to know how much current flowing through the base and diodes ? The current flow through the resistor R6 = (9-1.4)/1K = 7.6mA i supposed the to
I think Millman's theorem wont help me. Below is my simplified circuit in which am suppose to calculate total current when the transistor is ON. Consider diode drop as 1V, transistor Vce as 0.7. when transistor is ON, we see 3 current loops i.e. R2,D1,R1,U1,D2,R4 and R5,R6,U1,D2,R4 and R5,R3,D2,R4. so how to calculate total current I1,+I2+I3 ?
Software for ease of calculation. transistor.rar --- with installation transistorS.rar --- no installation
The circuit doesn't provide reliable current limiting. The maximum output current depends on input voltage and transistor current gain.
Hi all, I have to perform an experiment on my own. Experiment title is 'find H parameters of BJT transistor'. I don't have a clue what to do. I am asked to show hie, hfe, hoe calculated values in lab that should match to specification sheet of transistor. please tell me how to proceed step by step. Thanks in advance.
I'm guessing you are ignoring base current and hfe in your assumptions. I am afraid, boylesg is not familiar with transistor basics (operation principles).
How to calculate base current of a NPN transistor with collector current 50amps?..
because there is no such transistor with those specs 2SD1275 is rated 60V and 2SD1275A is rated 80V
Columns are A -> G Rows are 21 -> 24 IB= column contains the formula =E21/C21 RB= column contains the formula =(B21-D21)/F21 They are based on the equations here:
What transistor are you having Most Multimeters have hfe detectors use them they are more helpful if you want to know whether your tranny is working or not
Never mind the 555 and everything to the left of it - have a good understanding of that part. But I don't understand hoiw the designers of the circuit (below) have come of with the resistor values on the base of the BC327 and the base of the Darlington. I have had a stab based on a 555 puting out from 50 to 100mA but I have not come remotely near
Hi My friend I don't know that is there any site available or no , but i want tell you if i have the problem like your problem what i will do : I will read it's datasheet and write maximum IC and hfe and GBTP of current and break voltage , in a paper and try to compare them with transistors that i have ever used or know , or will search in my da
can i use BF494 transistor in place of BF199 transistor and BC549 transistor in place of BC547 transistor ?
what i can tell you is hfe is the beta gain of the BJT. It is given in datasheet of the transistor. I don't exactly know about the other two parameter. Umair ---------- Post added at 23:31 ---------- Previous post was at 23:21 ---------- what i can tell you is hfe is the beta gain[/B
You need to stop thinking about the transistor as a resistor... it acts like a diode, so best to think of it as one. Here are your steps to analyze the circuit: Need Ic = 10 mA (max) Most BJT's need 0.7V across the base-emitter junction to turn on. Looking at hfe (DC current gain) on the spec sheet, you'll see that a BC109 has a minimum (...)
I wanna know exactly how a transistor amplifies any signal
Hello All, I am trying to work with M34063 with 2SB1386 transistor for stability. There is a lot circuit diagram about these combination on internet. What I want to ask is, Initially when i brought the transistor 2SB1386, its was 2SB1386Q i.e. hfe range 120 t0 270. Now i am not able to find the same, What i got is 2SB1386R. When i
Hi, I buiding simple transistor switch circuits using 2n2222. I looked at the datasheet for the value of hfe.the datasheet gives many values of hfe. how do I know which value to take for my calculation. the values range from 35 to 300. please help me with this. thank you.
how much difference will a transistor with hfe 15-20 & 20-25 will bring to the circuit while all other parameters being same.
Hi, I'm pretty new to the forum. So I hope I posted on the right channel. I want to ask about the measurement condition that is put next to transistor parameter. I have BC846A from NXP. The datasheet can be downloaded from here. The datasheet sa