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# Transistor Hfe

97 Threads found on edaboard.com: Transistor Hfe

## VCE(sat) and hFE improvement

hfe is used with a linear transistor that is not saturated, the datasheet shows a Vce of a few volts to 10V. The datasheet for most transistors shows the saturation voltage drop when the base current is 1/10th the collector current disregarding the hfe.

## icbo and iceo in transistors...

A common emitter transistor is an amplifier. It amplifies its collector to base (icbo) leakage current.

## Common Emitter Transistor Circuit

Well, it's not quite that simple. What's the saturation voltage of the transistor? What's the Vbe?(You probably assumed 0.7, but it could be something a little different. Is the transistor GUARANTEED to have a beta of exactly 150? I doubt it, there's usually a minimum/maximum range.

## constant beta of NPN transistor over a large range of ib or ic.

By design method, any architecture can realize a constant current gain(beta) over a large input (ib) range? Unlike the typical current gain as shown in this figure, the gain should be a constant line. 131995Don't know of any way to do that. Normally the voltage gain of a transistor is stab

## Measuring Hfe of a NPN power transistor with 5A of collector current

Hi, I need to measure hfe of a NPN power transistor with 5A of collector current. I found a lot of of circuits to measure hfe but no one has this characteristic. Regards, Fernando - PU2PLL

## in finding an equivalent transistor, what are the important parameters?

The original 2N3392 was called "general purpose", not low noise. The circuit has low currents in the transistors so 500mA max does not matter. The transistors are reasonably biased so high hfe does not matter. Many Japanese transistors like the 2SC945 have the same plastic case and pinning. if you buy an old 2N2925 then buy (...)

## bfp420 bjt biasing and where to find iv curves?

I am learning S53MV oscillator design. It is provided here: I want to understand how biasing was chosen for BFP420 bjt transistor. I cant find any I-V (Ib) curves in BFP420 datasheet. Prevously i biased FET ne3210s01 and it was pretty convient, because there was some I-V curves, where i can draw

## What is the problem with the FM Transmitter circuit and my layout ?

I do not like the way the input transistor is dc biased. It is likely that transistor is fully saturated (collector voltage either at 0v DC or at 3V dc, instead of what it should be around 1.5 v DC). you can measure collector voltage with a voltmeter

## What is the hfe range of this npn transistor?

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

## Astable Multivibrator using Transistors

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

## low noise npn faster than mat12 sought

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?

## What is a Harris C9006 800637 TO-3 package used in an oscillator/driver circuit?

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

## Poweer transistor low "on" voltage

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 (...)

## PNP Transistor to control Tx module not working

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

## Transistor substitute/equivalent?

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

## Transistor as a switch

I want to design transistor as a switch.Any ideas on how can i begin.Every text that we have been taught uptil now discusses it but is silent about design.

## IDENTIFY Transistor from its Hfe Value

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 (...)

## datasheets Hfe's graph

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 (...)

## Common Emitter amplifier base current

113554 Ok so I have a really simple Common Emitter amplifier (I know it's not a very reliable circuit, but please ignore that). I'm a little confused as to how I select the base current. I have the equations: Vcc=IB*RB +VBE and VCC=IC*RL + VCE The component values are select so that IB makes VCE half the power sup

## Linear power supply series transitor

You don't need to calculate the base current depending on Vout. You need the base current for I out. Say you want 16V out and the Vbe of the transistor is 1.2V then you need to set the base to 17.2V to get 16V out. If your load at the emitter draws 1A at 16V , then your base current (assume hfe of 1000) will be about 1mA. Whatever the base is

## pwm to control proportional valve

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

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?

## CE amplify positive half signals more than negative one !!!

Hello Dear All, i tried to design a simple CE amplifier but i found that it amplifies the positive half cycles more than negative ones !!!What possible faults that may cause this error ? The gain is supposed to be 20 (but it is 24 after design acceptable) Rin > 2Kohm Beta for this transistor ~= 255 Is = 14.34 *10^-15 A Freq = 20 Hz -- 20 K

## Driving 24Vdc Solenoid valve with Transistor or MOSFET?

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

## How to drop off a couple of volts.

You can use a zener/transistor pre-regulator. Take a look at You can use LM317/337 regulators. LM317 has no max input because there is no ground connected directly to the regulator, there is only a max allowed IN/OUT voltage difference which is 40v, i

## difference between DC small signal gain and AC small signal gain ?

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 (...)

## How to calculate Zin and Zout for input and output matching network?

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

## Scaling and buffering an analog signal cheaply

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?

## A question about imput impedence

Question is pure theoretical. Input impedance equation should be solved using four-pole parameters of transistor. Expression is needed and not numerical result.

## Confused by transistors and base leg resistors!

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 (...)

## [MOVED] Triangular Wave Generator

It's unclear what causes the distortion. With MPSAxx transistor models you see only small deviation from ideal waveform. Although current mirors might be not well matched, this won't cause nonlinearity.

## the right transistor??

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

## Unbalanced "phantom" power

Would it be smarter to use a transistor with min hfe of 100 or min hfe of 250? hfe is AC current gain and has almost nothing to do with AC voltage gain. Since your buffer is an emitter-follower it does not have any voltage gain anyway. When the AC hfe is high then the DC hfe is also high (...)

## Equivalent to transistor 2d c 5609

Bruno, At the page bellow, you can find 2DC5609 parameters : Clicking at 2DC5609 equivalent, results in that parameters : In fact, the only

## [MOVED] Low Ib current NPN transitor for PIC, Ic=1A

Ib = Ic/hfe so for 1 Amp collector current, the base current will be 1/hfe. In theory, any transistor with a collector current rating of at least 1 Amp and a hfe of at least 40 could be driven by the PIC. There are thousands of such devices on the market but not all may be avaialble locally to you. Please note that those (...)

## Transistor base current for this circuit ... Help

I think your estimate for current through R6 is pretty accurate. However, diode drop (ssumed 0.7V) is also slightly current dependent, so you should check on data sheet and re-iterate if you want to be very sure. Regarding base current: It is quite small, but because it is dependent on hfe (the current gain) of the transistor It will vary aa lot

## current through series/parallel circuit

The circuit in post 1 is quite easy. You can simplify it like in the pic below. The circuit in post 3 is much more difficult. There are 2 possibilities: If the transistor is saturated, then we can estimate Vce = 0.1V. If the transistor is not saturated, then Ic = Ib * hfe. In either case you need to write out a set of l

## Transistor base resistor calculator

Software for ease of calculation. transistor.rar --- with installation transistorS.rar --- no installation

## Transistor current limiter

The circuit doesn't provide reliable current limiting. The maximum output current depends on input voltage and transistor current gain.

## How to find H-parameters of like hie, hoe,hre,hfe ?

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

## Self biasing a transistor

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).

## Transistor current calculation

Ib > (Ic/hfe) Use a value of Ib that is much greater than Ic/hfe, to ensure that the transistor is fully on (saturation mode). Hope this helps. Tahmid.

## Darlington transistor 2SD1275B

The measurements with a multimeter hfe tester are meaningless. SD1275 current gain is > 1000 (as with any darlington). But the transistor has integrated resistors that give a low hfe reading with the low currents used by the hfe testers.

## Transistor biasing calculation problem.

They used this value to make sure the transistor is fully saturated at all values of hfe/volt drops across D1/10 ohms o/p of NE555. . . Frank

## Transistor test cct diagram

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

## Calculating resistor values in this circuit.

One problem is that the collector load for Q2 is a transformer. This will have a very low DC resistance ( .5 ohms?) so the output stage will have a potentially huge current before it saturates. Lets presume an output current of 5A, the darlington transistor will have a hfe of 1000 or so, so the base current ot get this is 5/1000 = 5mA, as there ar

## looking for equevalent transistor info

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