Sign in
Search Sci.Electronics.Design
design by Keywords
8051 | Amplifier | AVR | CMOS | Converter | DAC | Diode | FPGA | GPS | I2C | IDE | Laser | LCD | MOSFET | Op-amp | Oscillator | Oscilloscope | PID | PLL | PSU | PWM | RFID | RS232 | RS485 | SMPS | Spice | Transformer | Transistor | TTL | USB | VCO
Ads
See Also
Transistor
Sci.Electronics.Design is a worldwide Usenet news group that is used to discuss various aspects of Electronic Circuit Design.
We found 750 threads matching "transistor"
You are looking at page 1 of 19.
The most relevant threads are listed first
Best way to protect a transistor from overcurrent?
CJ - 2009-07-20 15:16:00
I have a project that involves using a transistor to drive an external
device. The external device requires 500mA and my parts are sized to
handle this fine.
My concern is that if the external device fails or is improperly
connected, it is going to instantly destroy the transistor.
What wo...
looking for a transistor
2008-01-01 16:48:00
I need to switch some GE #44 lamps from a TTL output. #44 lamps are 6.3 volts
at 250 ma, so I'll need a transistor to do the real work. Unfortunately, it's
just a hair too much power for one of the hundreds of surplus 2n2222's I keep
around to do almost everything else here. Can someone sugges...Need Help with Design
BobP122 - 2008-01-20 18:04:00
Hi,
Could use some help with configuring a:
1 Battery connected to
2. a Switch (2 contacts) connected to
3. a Transistor(& load)
The open switch switch turns on the transistor.
The closed switch turns off the transistor.
B+ > | | > Transistor (Switch open - Trans. OFF)
B+ > H > TrTran...Need BFY90 transistor preamp
Jim - 2009-03-24 14:52:00
Some time back I remember seeing a schematic and I think pcd artwork for a
single transistor 2 meter antenna preamp using a BFY90 transistor.
I now have a few of these transistors and have need for a small portable
preamp that would cover around 147 to 167 mhz with BNC input and output.
I h...Howdy the power to do?
FuGuntje - 2009-04-06 07:41:00
Hi, I am Fu Gung, evobiology student from Amobinia.
I about the transistor power gain read,
and want to amplify the AA cell power of 1.5 Ampere
and 3 Vold with the transistor gain so you
will help me drive cars with it.
The book has power gain for transistors very high, it says 100 000
and mor...Circuit explanation
ZZTech - 2009-05-26 18:40:00
I have been puzzling over the following simple circuit:
http://www.uoguelph.ca/~antoon/circ/2qflash.htm
Can anyone help me to rationalize how it works?
Here's my attempted explanation:
1. At the start both transistors are off.
2. The capacitor is charging through the 10M resistor
3. At...Huh - 2200V Transistor?
Frithiof Jensen - 2008-11-26 04:34:00
Just fell over this looking for something else: A ready-made cascode
transistor, like the discrete ones I used in my exam project 25 years ago.
Now, where can I get some Oil to put it in?:)
http://www.st.com/stonline/products/literature/ds/12919/stc03de220hv.pdf
...Understanding a split-mode power supply.
Sylvia Else - 2009-01-03 21:32:00
After my airconditioner failed the other day, and being reluctant to pay
a technician to come and fix it, I've been taking a look at its
electronics board.
It's clear that its power supply circuit has failed. From the board
itself I've inferred this partial circuit:
http://members.optusn...Re: Cons of FPGA
Rich Grise - 2009-04-17 12:31:00
On Thu, 16 Apr 2009 16:06:42 -0700, Tim Wescott wrote:
>
> Use vacuum tubes -- it's a proven technology :-).
I grew up on toooooobz - when they invented the transistor, it took
me awhile to wrap my head around how they worked; then along came the
JFET and I was, like, "Hallelulah! A transi...need fast switching transistor
Mark R Rivet - 2008-08-21 16:29:00
Hello all, I'm looking for a transistor that can handle around 80volt
and has a switching speed, full on to full off of 1nano second or very
close to that. Anyone have a source?
...ZVS converter - snubber helpful at turn-off?
Yzordderrex - 2009-10-15 10:34:00
I am looking at doing a half-bridge LLC resonant converter design.
Fairchild appnote AN-4151
Turn-on is not a problem as it is into zero voltage as the lagging
current commutates the current before the Fet turns on.
I am wondering if placing a small capacitor (100pf-1000pf) across the
Drain...Re: Whats different between these two circuits?
Don Klipstein - 2008-07-23 21:13:00
In ,
readeraz wrote:
> Ringing choke circuit and blocking oscillator are different names of
> oscillator.
> Are they same meaning or they are different circuit in practice?
> How to distinctly identify them?
Both resemble variants of the Hartley oscillator, with the capacitor
acros...Transistor arrays?
krw - 2009-09-02 20:23:00
Anyone have a handy transistor array (NPN RET or logic level NFET)
that'll easily drive LEDs? I need cheap (Joerg? ;) and small. Normal
RETs are in the $.08 range but only come in duals in a SOT-363 (six
lead) or some such. I'd like something with four or eight transistors
with a common emit...Simple switching circuit
2008-01-05 14:33:00
I have designed and built a circuit that consists of an infrared
emitter & detector along with a power transistor. The idea is that
when the beam of infrared light is broken, I want a small 2.5 Amp - 12
volt pump to turn on. I have it working with one problem... when the
beam is partially bloc...Best way for mounting high voltage transistors on heat sink
Saman - 2009-05-25 00:20:00
Hello, I have a board that has 8 transistors mounted on a heat sink. each
TO-220 transistor(IRF 630) dissipates about 10W. for lower voltages I
usually used rubber silicon pads for isolation. I have tested them and they
can dissipate up to 15W without making transistor too hot. Now I have a hi...Re: Germanium Transistor in Current Production
RST Engineering - JIm - 2009-10-31 15:08:00
Isn't Oliver Germanium still around?
Jim
"Fred" wrote in message
news:0a31b4f9-c50d-4d0c-95c6-68cc63498b19@b18g2000vbl.googlegroups.com...
> Does anybody know of any germanium transistor for audio use that are
> in current production?
>
> Also are the NTE102 and NTE103 or ...Re: OT: Rant on Dictatorship
Eeyore - 2008-03-25 21:18:00
John Larkin wrote:
> YD wrote:
> >
> > Most, if not all, of the world outside the US uses aluminium. But you
> > lot still measure in inches and pounds so I guess we'll just let it
> > lie as another charming little quirk of yours.
>
> Silly quirk, like refrigeration and airp...Re: EMI prevention / protection?
whit3rd - 2009-10-31 15:23:00
On Oct 30, 12:04=A0pm, Joerg wrote:
> Beads in front of opamp inputs or transistor bases also help.
Only as a last resort, surely!
The inputs and transistor bases are relatively HIGH impedance,
and beads are low-Z by comparison; I'd save those beads
for emitters where they have better m...Re: Why Is High Feedback Considered Bad In Audio? In Simple Terms
Jan Panteltje - 2009-01-23 18:47:00
On a sunny day (Fri, 23 Jan 2009 23:10:41 +0000) it happened
adrian@poppyrecords.invalid.invalid (Adrian Tuddenham) wrote in
:
> If you can be sure of keeping the amplifier within its working limits at
> all times, feedback is generally a good thing, but if you overload it
> (even slightly)...solar light detection (day/night) problems
Dan K - 2008-09-26 09:40:00
I just want a detector to tell if its day or night. Easy, right?
I started out with a photo resistor (CdS Photoconductive Photocell I
believe) in a voltage divider feeding a comparator. Worked fine on the
bench. Worked fine outside the first day. Stopped working the second day
(failed t...Balancing LEDs ?
Simon - 2008-08-08 11:26:00
I have a circuit which efficiently operates LED through transistor and
resistor using very ultra bright white 3.4v LED
My client wants me to run 1.8v LED on off same transistor with its own
resistor
I want good power usage efficiency because our product is soilar charged
into NiMH button...Re: Precision current mirror
2008-08-01 20:36:00
On 29 Jul., 22:42, "Tim Williams" wrote:
> Well, you can certainly make three transistors into a 1:2 current mirror,
> and generic transistors will go that fast. Tweaking the full 13+ bits
> accuracy out of it is your problem. ;-)
>
> Tim
snip
I guess Jim could answer this but, if ...Circuit protection ideas?
2008-07-02 09:59:00
I am putting together a design for an RGB LED controller using PWM to
control color and intensity on RGB LED's. I want the controller to
work with various LED's, so I am using a 4 position screw terminal.
The controller just supplies 12 volts and switches ground on the 3
other terminals to effe...Buck voltage controlled by an MCU
2008-08-01 11:07:00
Is it possible to use the voltage divider in the feedback loop of an adjustable
buck converter to continously change the desired output voltage over time ..?
How fast could the feedback voltage be allowed to change without compromising
stability ..?
(example chip: http://focus.ti.com/lit/ds/...Re: OT: Where to sell MOSFETs back to a supplier
Joerg - 2009-09-24 19:54:00
Klaus Kragelund wrote:
> Hi
>
> I should have posted this only on at Sci.Electronics.Components, been
> a while when I last looked at the NG, but now its all spam.
>
> Anyway, I accidently got hold of some really expensive MOSFETs
> (STW45NM50, 7USD a piece) without knowing what they...Re: More on cracking the 433.92 MHz light remote
Jan Panteltje - 2009-03-07 13:37:00
On a sunny day (Sat, 7 Mar 2009 10:12:17 -0800 (PST)) it happened linnix
wrote in
:
> I will try to just record and compare the signal with the uC. I am
> thinking about IR receivers tapped into the unused 2nd and 3nd phone
> wires.
When I did the IR learn thing with this soft, long ...Re: My Vintage Dream PC
Ahem A Rivet's Shot - 2009-06-02 09:40:00
On Tue, 02 Jun 2009 08:10:10 -0400
Roland Hutchinson wrote:
> Since you submitted a timely correction, we'll also overlook that "RAM
> memory" is a parallel construction to "PIN number", "TCP protocol" or
> "LED diode".
OTOH transistor transistor logic actually makes sense, not all
...Re: Need design for 120VDC 60mA constant current supply
whit3rd - 2009-03-11 18:15:00
On Mar 9, 9:11=A0am, John Nagle wrote:
> John Larkin wrote:
[ use two power supplies, and a class G type amplifier that
takes current from both]
>
> =A0 =A0 But how to regulate all this?
>
The selector coil is floating, nicht wahr? A sense resistor on
the (-) terminal to ground ...Transistor Theremin by Alexander Zeyliger
Andreu - 2008-08-08 20:01:00
I would like to build the Transistor Theremin designed by Alexander
Zeyliger but I need some help. I have some questions to be answered, I
know they are so basic....
What kind of capacitor is needed? I mean: ceramic, electrolytic,
etc...
It will works if the power supply is a 12VDC battery ch...Re: #6 screw as heatsink
sycochkn - 2008-03-09 11:43:00
"mkr5000" wrote in message
news:1d4fbfb2-aa58-43ad-88cd-486fd53c06a5@u69g2000hse.googlegroups.com...
> Just sharing....
>
> You know the little hole in a TO220 tab?
>
> Just a 1/2" to 1" machine screw with nut tightened to it does a very
> respectable job of sinking heat.
>
> ...Re: monitoring heatsink temperatures
whit3rd - 2008-07-25 13:15:00
On Jul 25, 3:08=A0am, Jamie Morken wrote:
> legg wrote:
> > > I have a PCB with 4 heatsinks that I would like to monitor the
> > > temperature of for feedback to the cooling fan controller.
> Any other TO-220 analog temperature sensors besides the LM35?
The temperature sensitivit...Re: circuit that sumulates a high voltage zener with low temperature coefficient
Tom Bruhns - 2008-02-07 00:38:00
On Feb 6, 7:52 pm, "mook Johnson" wrote:
> I'm looking to replace a stack if 1N4085 low TC zeners used to make a stable
> 600V reference. Any ideas for a non-zener based shunt regulator that would
> give a stable 600V. load is less than 1mA.
>
> thanks
You didn't say how stable. "...Re: abusing transistors
pawihte - 2010-01-05 14:58:00
Wimpie wrote:
> On 5 ene, 17:54, "pawihte" wrote:
> > Wimpie wrote:
> >
> > > I know from experience that reverse biasing BE
> > > junctions, destroys low current HFE completely (BC84x
> > > series).
> >
> > If you'll forgive me for inserting a beginner's question here:
> > Des...Re: Anyone using a Welec W20xxA DSO?
Falk Willberg - 2009-07-09 14:55:00
Jon Kirwan schrieb:
> On Thu, 09 Jul 2009 06:46:13 -0700, Joerg
> wrote:
...
> > Yes, now I remember you mentioning that in the German NG.
> >
>
> Which newsgroup is this. I'd like to start reading it. I need to
> work on German
Die Gruppe heißt: de.sci.electronics. Yo...Re: Electronic load advice
Leon - 2008-02-02 23:48:00
On 3 Feb, 01:46, Richard Henry wrote:
> I need to test some battery packs. We predict the load of the target
> product will cycle from high power (80 W for 10 ms) to low power (5 W
> for 240 ms) during operation. I would like to simulate that load
> including the dynamics in the battery...=?ISO-8859-1?Q?Re:_High_voltage_switch_<500=B5s_and_max_7kV?=
Winfield - 2008-01-17 06:09:00
Joerg wrote:
>
> Win, you might get a kick out of this pulse generator
> from the late 70's, see figure 1:
>
> http://msc.eldoc.ub.rug.nl/FILES/root/WiersmaDA/1978/OptCommdeBree/1978OptCommdeBree.pdf
Hey, thanks! Very nice. They get 15ns pulses,
2 to 3kV they say, but that's not to...simulation yields negative current.wierd!!
2008-07-30 22:59:00
hello.
i have a problem in figuring out the wierd negative current that
appeared in the cct i was simulating. a 5 volt battery to the base of
transistor, 12 volt battery via a relay to the collector and ground to
the emmitter. the transister is an npn transistor along with the
resistor to base ...Re: Help with power issues
linnix - 2009-03-31 21:47:00
On Mar 31, 6:05 pm, linnix wrote:
> On Mar 31, 4:36 pm, Eeyore
> wrote:
>
> > James Arthur wrote:
> > > The problem with your zener shunt regulator idea is that it
> > > won't work.
>
> > You got it. They are the lousiest most power hungry 'regulators' in the world.
> >...using transistors to switch LED's with floating load buck regulator - problem
CJ - 2009-07-14 12:55:00
I have a project I am trying to do where I use a Zetex ZXLD1360
constant current buck regulator to drive either one of two strings of
three high power LED's.
I have string of blue and a string of red LED's. The output from the
reguator is connected to two NPN transistors, which control which
...Problems to find the correct load line
2008-10-15 01:55:00
I have some problems about load line of this circuit...
http://img406.imageshack.us/img406/2959/loadlineqn4.jpg
Usually, to find load line i calculate current in transitor when
transistor is shorted and when is open circuit. In this case, when
transtistor is shorted, vout=vss and current in tran...