Bipolar transistor bias question

Started by billbowden in sci.electronics.design6 years ago 62 replies

I have a switching application where a single bipolar transistor might be used. The AC input is about 300mV and the transistor needs about 700...

I have a switching application where a single bipolar transistor might be used. The AC input is about 300mV and the transistor needs about 700 mV to switch on. My idea is to construct a voltage divider using a diode which will produce about a 600mV drop across the diode and a voltage divider of 2 equal resistors to set the transistor base voltage at about 300 mV so the transistor will sw...


pointers to transistor (semiconductor) curve tracer circuits/projects

Started by Anonymous in sci.electronics.design4 years ago 138 replies

I find myself in a situation where I am repairing some high end audio amps and cassette decks that have house numbered semiconductors, mainly...

I find myself in a situation where I am repairing some high end audio amps and cassette decks that have house numbered semiconductors, mainly transistors as well as JDEC p/n that are NLA. I have found a few transistors that are dead and need to be replaced. Fortunately, they are in parts of the amp where the other channel has an identical transistor. Having one transistor as a bas


Fail to amplify 27mhz rf using mosfet IRF843

Started by Anonymous in sci.electronics.design6 years ago 20 replies

I found old mosfet transistor IRF843, using 20k and 70k resistor, i manage to set the voltage at transistor gate to 3.9 volt and using 1uF to...

I found old mosfet transistor IRF843, using 20k and 70k resistor, i manage to set the voltage at transistor gate to 3.9 volt and using 1uF to channel the 27mhz rf signal to the transistor gate, i manage to get an audio from 8ohm speaker connected to the transistor drain. I'm using about 5.3 volt power supply from transformer. The audio is loud and clear. The mosfet gate can received


Transitor as heater

Started by George Herold in sci.electronics.design9 years ago 62 replies

Transistor as heater/ temp sensor. So in looking for a small heater one idea is to use a transistor as heater. And to take the idea one step...

Transistor as heater/ temp sensor. So in looking for a small heater one idea is to use a transistor as heater. And to take the idea one step further to use the same transistor (sequentially) As first a heater then a temp sensor. So the first question is then how to use it as a heater. I was thinking of controlling the current At some fixed voltage.. something like this, https://www...


460GHz Vacuum Transistor

Started by amdx in sci.electronics.design5 years ago 47 replies

Well not a exactly a vacuum, they fill it with helium. "...NASA?s Ames Research Center is going back to the future with its new vacuum...

Well not a exactly a vacuum, they fill it with helium. "...NASA?s Ames Research Center is going back to the future with its new vacuum transistor ? a nanometer-scale vacuum tube that, in early testing, has reached speeds of up to 460GHz." > https://www.extremetech.com/extreme/185027-the-vacuum-tube-strikes-back-nasas-tiny-460ghz-vacuum -transistor-that-could-one-day-replace-silicon-fets


How to determine Zin, Yout for RF transistor, from A parameters

Started by Anonymous in sci.electronics.design5 years ago 101 replies

Could some RGF/microwave guru on this newsgroup please help ? I am looking at the datasheet for a ONSemi RF transistor, with the S parameters...

Could some RGF/microwave guru on this newsgroup please help ? I am looking at the datasheet for a ONSemi RF transistor, with the S parameters listed for various frequencies. What would be a quick and easy(that I can code as a simple C program) way to convert these to the corresponding Zin and Yout. Thanks in advance for your hints/suggestions.


Digital transistor?

Started by Sylvia Else in sci.electronics.design6 months ago 13 replies

https://www.farnell.com/datasheets/2353855.pdf I bought a few of these. I don't know what is intended by "digital transistor" since the...

https://www.farnell.com/datasheets/2353855.pdf I bought a few of these. I don't know what is intended by "digital transistor" since the charge storage time defeats any attempt to use them at a high frequency, and there's no way to add a Schottky diode to prevent saturation, or a speed-up capacitor across the base resistor. I'm using this and the corresponding PNP type to do level shift...


Behavior transistor models?

Started by Robert Baer in sci.electronics.design8 years ago 20 replies

Where can one get them, and is there a wide range of transistor type represented? How good are they, eg: E-B breakdown correct, beta at...

Where can one get them, and is there a wide range of transistor type represented? How good are they, eg: E-B breakdown correct, beta at given sets of Ic VS temp correct?, Vbe VS temp and VS Ic correct? Are there models for each manufacturer?


single transistor oscillator

Started by Vivek N in sci.electronics.design9 years ago 11 replies

I tried building a single transistor LED flasher like this...

I tried building a single transistor LED flasher like this : http://cappels.org/dproj/simplest_LED_flasher/Simplest_LED_Flasher_Circuit.html I didn't have the recommended 2n2222 - I tried with a BC548, 2n2369 and 2n3055 - None of them work. I'm using a trimpot set to 2 kiloohms and a 470 microfarad capacitor. Instead of a 100 ohm resistor I put 3 superbright LEDs in series. I get 1.2 v...


fast ramp follies

Started by John Larkin in sci.electronics.design5 years ago 139 replies

OK, I need to charge a capacitor with a stable constant current. The desired slope is about a volt per nanosecond. So I did...

OK, I need to charge a capacitor with a stable constant current. The desired slope is about a volt per nanosecond. So I did this: https://dl.dropbox.com/u/53724080/Circuits/Fast_Ramp.JPG Things like this tend to oscillate, so I used a fairly slow, high-beta transistor, BCX71K. The ferrite in the collector is supposed to isolate the ramp cap from the transistor capacitance and make ...


LTSpice Help

Started by OldGuy in sci.electronics.design9 years ago 23 replies

I am new to Spice as well as LT Spice. I have input most of my circuit after spending much time looking for components. I have not run the...

I am new to Spice as well as LT Spice. I have input most of my circuit after spending much time looking for components. I have not run the circuit yet since I have a hole where a unijunction goes. The circuit additionally uses a triac, scr and transistor. I found the *Programable Unijunction Transistor pkg: TO-226AA .SUBCKT X2N6027 1 2 3 for a "generic" (to me) unijunction. B...


The Transistor will Never Work

Started by Unlisted in sci.electronics.design3 years ago 19 replies

Its been over 70 years since scientists began trying to invent a device to replace vacuum tubes. This device was named the TRANSISTOR....

Its been over 70 years since scientists began trying to invent a device to replace vacuum tubes. This device was named the TRANSISTOR. While it's a catchy name, it failed to work as predicted. How these scientists ever expected a piece of rock inside a container, with wires attached, to control the flow of electrons, is a mystery. After all, its a known fact that rocks do not conduct electric...


Germanium Transistor in Current Production

Started by Fred in sci.electronics.design13 years ago 22 replies

Does anybody know of any germanium transistor for audio use that are in current production? Also are the NTE102 and NTE103 or any other NTE...

Does anybody know of any germanium transistor for audio use that are in current production? Also are the NTE102 and NTE103 or any other NTE offerings any good for audio, fuzz boxes etc?


How to select transistor for oscillator ?

Started by Anonymous in sci.electronics.design4 years ago 45 replies

Could some electronics guru here please help ? What is the best way to select a transistor for an oscillator ? Consider a Colpitts oscillator...

Could some electronics guru here please help ? What is the best way to select a transistor for an oscillator ? Consider a Colpitts oscillator running at 5 MHz. The following are the analysis steps. 1. Select a value for the LC tank capacitor C1 = C2 = C 2. Select a load e.g., R=50 Ohm 3. To start oscillations, gmR > C2/C1. In this case gmR > 1 4. Using the oscillation frequency and


Flashlights

Started by Tim Williams in sci.electronics.design5 years ago 14 replies

These are fun! https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg Triple 'LVC buffer drives the power transistor at 5 or 6...

These are fun! https://www.seventransistorlabs.com/Images/FlashlightTrio.jpg Triple 'LVC buffer drives the power transistor at 5 or 6 nanoseconds risetime, not bad at all. Design is very hackable; by changing around a couple of resistors, it makes a portable bench supply! Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https:/...


Transistor Conversion of Tube Amplifier

Started by Kevin Foster in sci.electronics.design6 years ago 15 replies

The circuit linked below appears to be a conversion of a three stage inverting tube amp tube to a transistor circuit, powered by...

The circuit linked below appears to be a conversion of a three stage inverting tube amp tube to a transistor circuit, powered by 3VDC. https://app.box.com/s/dwflbolnqe58ra9c1kssqjuq14dulxo0 It appears to be intended to capture high frequency ambient signals and re-broadcast them. It may also be designed to self-oscillate to add a carrier wave. In any case, I would like to build it o...


Power NPN transistor N344AB

Started by slampen in sci.electronics.design12 years ago 29 replies

Hi, My Peugeot 406 heater blower control module ceased to work the other day, and its power transistor is open. Must be an NPN since it is...

Hi, My Peugeot 406 heater blower control module ceased to work the other day, and its power transistor is open. Must be an NPN since it is supposed to PWM the blower motor to earth (-12V). When searching N344* I find a lot of references to 2N344n.. (2N3440, 2N3442... etc) but not this the exact version. I've uploaded an image of the 'fat' case here: http://kuntigi.net/download/N34...


PNP for soft switch and reverse battery protection

Started by Peabody in sci.electronics.design6 years ago 66 replies

I'm working on a small circuit that will be powered by a 9V battery. I would like to combine the functions of a soft power switch and reverse...

I'm working on a small circuit that will be powered by a 9V battery. I would like to combine the functions of a soft power switch and reverse battery protection in a single device. I think the answer may be to use a PNP transistor on the high side, with a base resistor to ground - actually to ground through a physical momentary switch, or indirectly to ground via an NPN transistor cont...


Exploring Jupiter's moon, Europa, possible with silicon-germanium transistor technology, radiation proof transistors...

Started by Jan Panteltje in sci.electronics.design14 hours ago

Exploring Jupiter's moon, Europa, possible with silicon-germanium transistor technology ...

Exploring Jupiter's moon, Europa, possible with silicon-germanium transistor technology https://www.sciencedaily.com/releases/2022/09/220930163205.htm radiation proof transistors...


TRANSISTOR SIV300004 needed....

Started by jusme in sci.electronics.design14 years ago 2 replies

or equivalent. I only need one but would like to have some spares. I have looked all over. I would even take a datasheet. Oh, please email...

or equivalent. I only need one but would like to have some spares. I have looked all over. I would even take a datasheet. Oh, please email if you have one/any as I don't check here often. Thanks for any help. j/b