Peavey Amplifiers

Started by Tim Wescott in sci.electronics.design10 years ago 10 replies

Anyone know where to get schematics for Peavey amps? Peavey Mark III Bass Head, if it makes any difference. In trying to find the low-level...

Anyone know where to get schematics for Peavey amps? Peavey Mark III Bass Head, if it makes any difference. In trying to find the low-level problem I dumb-thumbed, and dragged a scope ground across a power transistor -- and most likely fried it. It's not my amp!! So now I have at least two problems to diagnose and fix. And it's a house-numbered transistor, for my sins. So, if you...


Behavior transistor models?

Started by Robert Baer in sci.electronics.design7 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.design8 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...


Two Tones, One Transistor

Started by rickman in sci.electronics.design9 years ago 25 replies

I seem to recall from long, long ago, that the DTMF phones that Ma Bell put out used a single transistor to produce both tones. I can't find...

I seem to recall from long, long ago, that the DTMF phones that Ma Bell put out used a single transistor to produce both tones. I can't find any info on how this circuit would operate. How can you create a circuit that will resonate at two frequencies at once? How did Ma Bell do it? Rick


BJT saturation

Started by Anonymous in sci.electronics.design9 years ago 30 replies

Regarding BJT saturation point, the books say that the transistor is said t= o be saturated if increasing Ib no longer increases Ic. For example,...

Regarding BJT saturation point, the books say that the transistor is said t= o be saturated if increasing Ib no longer increases Ic. For example, if I h= ave a circuit where the the collector of NPN is at +5V through a 1K resisto= r, maximum Ic is 5ma. Assuming hfe is 100, above 50uA of Ib doesn't increas= e Ic due to 1K resistor. Is this the saturation point for the transistor? I= f this is ...


fast ramp follies

Started by John Larkin in sci.electronics.design4 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 ...


NPN - linear or saturation region region for GPIO switching

Started by Anonymous in sci.electronics.design8 years ago 11 replies

I am using a general purpose BC846 NPN transistor collector to pull an IC's= Enable pin down. The base of BC846 is driven a source that can only...

I am using a general purpose BC846 NPN transistor collector to pull an IC's= Enable pin down. The base of BC846 is driven a source that can only source= 0.2mA of current. Since I only need to turn ON the transistor to pull the = Enable pin down, base drive of 0.2mA is sufficient. Is 0.2mA of base curren= t sufficient to fully turn ON the transistor or it will operate in the line= ar region?...


LTSpice Help

Started by OldGuy in sci.electronics.design8 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.design2 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...


Planar NPN Transistor in Magic or Electric VLSI?

Started by Anonymous in sci.electronics.design5 years ago

Hi everybody, I'm going through Camenzind's Designing Analog Chips, and not far into it is the simple planar NPN transistor; how would I...

Hi everybody, I'm going through Camenzind's Designing Analog Chips, and not far into it is the simple planar NPN transistor; how would I represent this in Magic? Assuming the substrate is P, the N well for the collector makes sense, as does the P diffusion for the base, however the n+ emitter region within the base which resides in a N well - we could get away with an n+ contact reg


Germanium Transistor in Current Production

Started by Fred in sci.electronics.design12 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.design3 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.design4 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:/...


where to find a list of ID codes on recent SMT parts?

Started by Jamie in sci.electronics.design10 years ago 4 replies

Today at my bench, my boss wanted me to look at a simple inverter for a panel touch screen LCD monitor. While collecting information I found...

Today at my bench, my boss wanted me to look at a simple inverter for a panel touch screen LCD monitor. While collecting information I found that the ID codes on the smt did not match what usually go by. For example I had a "2A (underscore V) 3D" on a sot23 transistor. The chart tells me it is a 3906 (pnp) transistor however, I found that it is actually closer to being a fet transi...


TL431 supply current/gain Q

Started by bitrex in sci.electronics.design5 years ago 19 replies

Looking at the internal schematic of the TL431: http://www.tubecad.com/2005/January/18/Shunt_Regulator_10.gif It looks to me like startup of...

Looking at the internal schematic of the TL431: http://www.tubecad.com/2005/January/18/Shunt_Regulator_10.gif It looks to me like startup of the bandgap reference occurs as "REF" is brought up to some voltage slightly above 1.2V, causing the leftmost diode-connected transistor to turn on and drive current into the transistor with its base connected to 1k, which then bootstraps current ...


HEMT

Started by ECS.MSc.SOC in sci.electronics.design10 years ago 71 replies

Hi all I want to create a circuit, in which is used discrete elements. one of the elements that I need to use is HEMT transistor because of...

Hi all I want to create a circuit, in which is used discrete elements. one of the elements that I need to use is HEMT transistor because of its fast switching transition. Is there HEMT transistor as discrete element? If yes, is that usual to use in the board level circuit? Regards,


Convert Odd Tube Circuit to Transistor

Started by Ben Hartley in sci.electronics.design10 years ago 39 replies

I would like to convert this tube amplifier to solid state. IOW a transistor circuit that uses the same three stage format ... a "faithful...

I would like to convert this tube amplifier to solid state. IOW a transistor circuit that uses the same three stage format ... a "faithful reproduction", if you will. Not something "better". Can anyone please recommend suitabletype of circuit and parts? http://www.4shared.com/photo/VT-DRz5g/Tube-Circuit.html Of course, it will be powered from 12VDC, not the HV of the original tubes. ...


RF transistor load pull simulation with SPICE

Started by amal banerjee in sci.electronics.design2 years ago 1 reply

Could some electronics guru here please clarify this ? Is it feasible to perform load pull simulation for a RF transistor using SPICE's...

Could some electronics guru here please clarify this ? Is it feasible to perform load pull simulation for a RF transistor using SPICE's transient(large signal) analysis scheme ? Of course the load or source has to be changed over a range of values, and for each run measure the RMS input output power ? Thanks in advance.


Measured reverse base damage of NPN

Started by Mikko OH2HVJ in sci.electronics.design3 years ago 15 replies

I remember there was some discussion if low reverse currents can damage a bipolar transistor. I got a new toy (HP 4142B with 3 SMUs) and...

I remember there was some discussion if low reverse currents can damage a bipolar transistor. I got a new toy (HP 4142B with 3 SMUs) and did some quick testing. It seems that even 1uA reverse current starts to destroy the transistor. Here's a graph that shows hFE as a function of amp-seconds from the base: https://plot.ly/~msyrjala/3/#/ I also did an another test with 0.1 for 2000s and ...


Theoretical Maximum Transistor Switching Speed (based on distances)

Started by Skybuck Flying in sci.electronics.design7 years ago 10 replies

Hello, For a while now I've been wondering what the maximum transistor switching speed would be. Today I tried a google but now clear...

Hello, For a while now I've been wondering what the maximum transistor switching speed would be. Today I tried a google but now clear answer came up, so I will try to come up/calculate an answer myself. I share it with you for feedback/verifieing/finding any mistakes I made. For now I will ignore heat problems and other kinds of problems for example someday somebody might want to...