Bipolar transistor bias question

Started by billbowden in sci.electronics.design3 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...


AI-generated technical documentation

Started by bitrex in sci.electronics.design1 year ago 6 replies

Input: "The voltage on transistor Q1 emitter should read 3.5 volts" Output: "The voltage on transistor Q1 emitter should read 3.5 volts. Set...

Input: "The voltage on transistor Q1 emitter should read 3.5 volts" Output: "The voltage on transistor Q1 emitter should read 3.5 volts. Set voltage of transistor Q1 to 2.5 volts. With the voltage from transistor Q1 set to 1.5 volts, pull transistor Q1 clockwise until power is pulled low, or transistor is out of circuit. Pull transistor Q1 clockwise to reset voltage and pull power ba...


Transistor Tester.

Started by Baron in sci.electronics.design6 years ago 1 reply

Hi Guys, A long time ago I came across and article that described a simple transistor tester. It was based on a multivibrator circuit and...

Hi Guys, A long time ago I came across and article that described a simple transistor tester. It was based on a multivibrator circuit and was able to identify which type "N" or "P" of the device connected to the test terminals. I've googled for "transistor tester" and get lots of hits trying to sell them but not what I'm looking for. Thanks: -- Best Regards: B...


Exhausted

Started by David Eather in sci.electronics.design4 years ago 48 replies

If any kind soul can help... There was a short post/note on SED or SEB about a transistor with a 2.5V max Vebo and another one with 3.0 max...

If any kind soul can help... There was a short post/note on SED or SEB about a transistor with a 2.5V max Vebo and another one with 3.0 max Vebo. I have spent hours looking for the transistors and have run out of options. Does anyone remember which transistor numbers these were? I'm adding transistor junction breakdown noise to a Arduino and they would fit the bill perfectly - an...


pointers to transistor (semiconductor) curve tracer circuits/projects

Started by Anonymous in sci.electronics.design2 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.design3 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


Transistor-Transistor TTL Logic and Totem pole output

Started by Patrick Chung in sci.electronics.design5 years ago 7 replies

By combining basic TTL Logic NAND gate with invertors and other gate any logical function can be realized in TTL technology. TTL family of logic...

By combining basic TTL Logic NAND gate with invertors and other gate any logical function can be realized in TTL technology. TTL family of logic circuits is specially empowered with TTL Totem pole output Read more: http://www.cirvirlab.com/index.php/electronic/181-transistor-transistor-ttl-logic.html


BJT or MOSFET for Current Source Circuit

Started by panfilero in sci.electronics.design6 years ago 28 replies

I'm looking to make a "Current Source" I'd like to supply a maximum of 10A, I'm thinking about putting a transistor at the output of an Op-Amp and...

I'm looking to make a "Current Source" I'd like to supply a maximum of 10A, I'm thinking about putting a transistor at the output of an Op-Amp and using the transistor to pull the 10A through my load. My question is, would I be better off using a MOSFET or a BJT for this (darlington or maybe even IGBT) it really just has to sit there and handle 10A... does this point towards which transistor ha...


A high power RF LDMOS transistor

Started by Michael A. Terrell in sci.electronics.design4 years ago 129 replies

This transistor looks interesting: -- Subject: Spelling Lesson The last four letters in American.........I Can The last four...

This transistor looks interesting: -- Subject: Spelling Lesson The last four letters in American.........I Can The last four letters in Republican.......I Can The last four letters in Democrats.........Rats End of lesson. Test to follow in


Transitor as heater

Started by George Herold in sci.electronics.design6 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...


Why Is Hall Effect So Slow ?

Started by Anonymous in sci.electronics.design2 years ago 10 replies

An actual electronics/physics question borne from a topic in a forum where they discuss electronics, not have feuds. An optocoupler uses a...

An actual electronics/physics question borne from a topic in a forum where they discuss electronics, not have feuds. An optocoupler uses a photo sensitive transistor. A transistor that is controlled by something other than base current. A Hall effect sensor is a transistor also not controlled by base current built by magnetism instead of light. I know for a fact that a simple, analog opto ...


High GBW jelly bean transistor

Started by David Eather in sci.electronics.design9 years ago 13 replies

Does anyone have a suggestion for a transistor (npn pref) that has a higher GBW than a BC547 or 2N2222 at 2 - 10 ma?

Does anyone have a suggestion for a transistor (npn pref) that has a higher GBW than a BC547 or 2N2222 at 2 - 10 ma?


460GHz Vacuum Transistor

Started by amdx in sci.electronics.design3 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


Transistor Checker

Started by Anonymous in sci.electronics.design6 years ago 8 replies

OK, I pretty much never used one. When the circuit would come alive, the sc= ope tells you if a transistor is bad. If not, the DVM or ohmmeter...

OK, I pretty much never used one. When the circuit would come alive, the sc= ope tells you if a transistor is bad. If not, the DVM or ohmmeter will. (yu= p, that old, I know others are older and actually want to query them so I c= an make sure not to do what they did) At any rate, the boredom does set in once in a while and go looking for tro= uble. In the B&K 520B transoistor tester, I may...


NPN Transistor Question

Started by Jim Thompson in sci.electronics.design5 years ago 34 replies

Being in the I/C biz, I don't keep up very well with what is available in the discrete transistor world. What I'm looking for is a...

Being in the I/C biz, I don't keep up very well with what is available in the discrete transistor world. What I'm looking for is a _readily_available_ NPN, highest fT, VCE < 15V, IC < 10mA Suggestions? Thanks! ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations


Transistor identification?

Started by DaveC in sci.electronics.design5 years ago 23 replies

Help with identifying a TO-92 transistor?(at least I think it?s a transistor?) Pretty vanilla-looking with National Semi logo. Marked: NS...

Help with identifying a TO-92 transistor?(at least I think it?s a transistor?) Pretty vanilla-looking with National Semi logo. Marked: NS 444 ST 13903 (The ?NS? is the logo.) Not enough 4?s to make up a standard 2N number, and 13903 looks like a date code? Ideas? Thanks,


Interfacing to tube logic circuitry

Started by Anonymous in sci.electronics.design9 years ago 11 replies

Specifically Nixie tubes. I have this counter that has a connector that provides me with all the active-low transistor drivers for each digit....

Specifically Nixie tubes. I have this counter that has a connector that provides me with all the active-low transistor drivers for each digit. What are the gotchas for using these lines with a uC input? I'm guessing that it's all very high impedance when the transistor is off, but what happens when digits switch? Isn't there a plasma in there and can there be high voltage spikes on the output...


common failure mode for digital transisors?

Started by Maynard A. Philbrook Jr. in sci.electronics.design6 years ago 2 replies

I do some repair work now and then and I got a HF transceiver that I once replaced a DTC114ES digital (pre biased) transistor. It didn't...

I do some repair work now and then and I got a HF transceiver that I once replaced a DTC114ES digital (pre biased) transistor. It didn't appear shorted, it just wouldn't turn on. I just got a call from the owner and from what he's telling me and from what I can gather in the schematic, it appears that maybe another digital transistor of the same type has failed, but only in a differe...


Transistor oscillator.

Started by Ian Field in sci.electronics.design4 years ago 56 replies

Is there a rock bottom oscillator that will free run at the frequency limit of whatever transistor is put in it? I was thinking of the common...

Is there a rock bottom oscillator that will free run at the frequency limit of whatever transistor is put in it? I was thinking of the common base job with a capacitor strapped from collector to emitter, but am unsure what to use as a collector load. Basically for testing how good are a collection of vintage germanium transistors. Thanks for any help.


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

Started by Anonymous in sci.electronics.design3 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.