Fast buffer idea

On Mon, 15 May 2017 21:00:54 GMT, Steve Wilson <no@spam.com> wrote:

>John Larkin <jjlarkin@highland_snip_technology.com> wrote:
>
>> On Mon, 15 May 2017 20:46:14 GMT, Steve Wilson <no@spam.com> wrote:
>> 
>>>John Larkin <jjlarkin@highland_snip_technology.com> wrote:
>>>
>>>> The current probe is twitchy. I like to add visible current-shunt
>>>> resistors to make it easier to probe. 
>>> 
>>>Nothing wrong with that, except you have to add separate node names to
>>>either side of the resistor. Then instead of plotting Ib(Q2) you will
>>>plot I(R12). The polarity will depend on the orientation of the
>>>resistor. 
>> 
>> LT Spice defaults to getting that backwards.
>
>So plot the twitchy base, emitter or collector current, and add a minus 
>sign if needed to make it correspond with the waveform.
>

I just flip the resistor.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

John Larkin <jjlarkin@highland_snip_technology.com> wrote:

> On Mon, 15 May 2017 21:00:54 GMT, Steve Wilson <no@spam.com> wrote:
 
>>John Larkin <jjlarkin@highland_snip_technology.com> wrote:

>>> On Mon, 15 May 2017 20:46:14 GMT, Steve Wilson <no@spam.com> wrote:
 
>>>>John Larkin <jjlarkin@highland_snip_technology.com> wrote:

>>>>> The current probe is twitchy. I like to add visible current-shunt
>>>>> resistors to make it easier to probe. 
 
>>>>Nothing wrong with that, except you have to add separate node names 
to
>>>>either side of the resistor. Then instead of plotting Ib(Q2) you will
>>>>plot I(R12). The polarity will depend on the orientation of the
>>>>resistor. 
 
>>> LT Spice defaults to getting that backwards.

>>So plot the twitchy base, emitter or collector current, and add a minus 
>>sign if needed to make it correspond with the waveform.
 
> I just flip the resistor.
 
As above. Now you are plotting I(Rxx) instead of IB(Qx). Rxx may be a lot 
harder to find on the schematic than Qx. Wases your time looking.

Also the extra part takes up more space and requires another node name so 
you are not trying to plot V(n00x), which may change as soon as you add 
or remove another node. Good luck trying to find the original node that 
you wanted to plot. Wastes your time looking.

There are cases where an extra resistor is actually needed, such as a 
base parasitic resistor or in the gate of a fast MOSFET. These can remind 
you to include the resistor in the pcb layout, and help determine the 
value needed in the circuit. In the case of the emitter or collector, it 
usually goes to ground or to another component, so you don't need to add 
another resistor to monitor the current.

On a sunny day (Mon, 15 May 2017 15:38:06 -0400) it happened bitrex
<bitrex@de.lete.earthlink.net> wrote in <zsnSA.28967$9o7.3799@fx12.iad>:

>>  http://panteltje.com/pub/build_it_and_testing_at_10V_IMG_6185.JPG
>>
>>       NO resistors
>> here without flash so you can read the mA meter:
>>  http://panteltje.com/pub/buid_it_and_testing_no_flash_IMG_6186.JPG
>>
>> Sorry for the crowded place, lots of things multitasking here.
>>
>> I did not load it, but it sure wanted to beep on my FM radio as I did not decouple the supply lines...
>> Old Trio Kenwood scope does not go that high.
>> Never underestimate El Pante
>>
>> Current does not increase from 5 to 10 V, did not try higher,,
>> The audio generator is Linux sgen.
>>
>> Now for the spice by those who have it!
>
>Yes, the basic topology is an _excellent_ performer at low quiescent 
>bias current, low frequency, and into no load! ;-)

Na, be a good sport, if I have time tonight I will add a 75 Ohm load,
and rebuild it so the driver PNP is making thermal contact with the output NPN (for each half).
I hope that will fix any thermal tracking.
The above setup I build faster than you spicers could enter it.
AND it is real, unlike in the matrix.. 
;-)

Hey I am well aware of all the potential problems and limitations,
but it is fun to test how real those are and if those REALLY are a show-stopper.

Always learning.

On a sunny day (Mon, 15 May 2017 15:33:15 -0400) it happened bitrex
<bitrex@de.lete.earthlink.net> wrote in <0onSA.73595$jO6.6010@fx41.iad>:

>On 05/15/2017 03:13 PM, Jan Panteltje wrote:
>
>> Well that is same as from black to white, works fine tough.
>> that is just the PNP conducting pulling the output.
>> This circuit has been used for video by me many many times.
>> Never ever failed.
>
>Ya I'm sure it works fine for composite video. If the risetime off the 
>porches is a little sluggish I don't think it matters much; there isn't 
>anything timing-critical to that transition as its just setting up the 
>luminance "data." Might make the edges a little fuzzy? Like "vintage warmth"

It (the amplifier) is > 5MHz bandwidth,
this is analog NTSC send down from the drone at 5.something GHz.
You do NOT want faster risetimes etc in analog PAL / NTSC video.
It only adds crap (plenty HF noise in that FM link) .
You are no video man it seems, you talk about 'porches' nobody in video does.

This was fun. Not bad for 3904s.
https://www.seventransistorlabs.com/Images/High_Speed_Buffer.png
See how it works with 10GHz transistors. :^)

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com


"bitrex" <bitrex@de.lete.earthlink.net> wrote in message 
news:vN0SA.45616$3M3.37466@fx16.iad...
> Diamond buffers are kind of cool, emitter feedback makes them linear and 
> they don't have much phase shift, but they kind of suck balls whenever you 
> want to actually move appreciable current with them which unfortunately is 
> exactly what you'd want to do with a buffer.
>
> I came up with this thing that uses a sort of MOSFET-BJT Sziklai pair 
> input-thing to drive boosting transistors to pump more dynamic current 
> into the output follower's bases to speed up the transitions. This is the 
> sim of it pushing a 100MHz square wave into a load using jellybean 
> transistors:
>
> http://imgur.com/a/bM8hl
>
> Fast recovery didoes from the bases of the boosting transistors to ground 
> and Vcc seem to speed up the transitions a lot.
>
> Version 4
> SHEET 1 1804 1564
> WIRE -16 -592 -16 -672
> WIRE 160 -592 -16 -592
> WIRE 320 -592 160 -592
> WIRE 480 -592 320 -592
> WIRE 624 -592 480 -592
> WIRE 896 -592 624 -592
> WIRE -16 -480 -16 -592
> WIRE 320 -480 320 -592
> WIRE 160 -464 160 -592
> WIRE 480 -464 480 -592
> WIRE 624 -352 624 -592
> WIRE -16 -320 -16 -400
> WIRE 160 -320 160 -400
> WIRE 160 -320 -16 -320
> WIRE 320 -304 320 -400
> WIRE 480 -304 480 -400
> WIRE 480 -304 320 -304
> WIRE 560 -304 480 -304
> WIRE -16 -256 -16 -320
> WIRE 896 -160 896 -592
> WIRE -576 -112 -576 -144
> WIRE -16 -112 -16 -176
> WIRE 624 -112 624 -256
> WIRE 624 -112 -16 -112
> WIRE 704 -112 624 -112
> WIRE 832 -112 768 -112
> WIRE -16 -32 -16 -112
> WIRE -576 -16 -576 -32
> WIRE -576 -16 -688 -16
> WIRE -64 -16 -224 -16
> WIRE -576 16 -576 -16
> WIRE 896 16 896 -64
> WIRE -688 32 -688 -16
> WIRE 320 96 320 -304
> WIRE -576 144 -576 96
> WIRE -16 144 -16 64
> WIRE 160 144 -16 144
> WIRE 256 144 160 144
> WIRE 896 176 896 16
> WIRE 544 192 320 192
> WIRE 160 208 160 144
> WIRE -16 336 -16 144
> WIRE 160 336 160 272
> WIRE 160 336 -16 336
> WIRE 320 336 160 336
> WIRE 544 384 544 192
> WIRE 896 384 896 256
> WIRE 896 384 544 384
> WIRE 992 384 896 384
> WIRE 1152 384 1072 384
> WIRE 1312 384 1232 384
> WIRE 1472 384 1392 384
> WIRE 1600 384 1472 384
> WIRE 1696 384 1600 384
> WIRE -416 400 -576 400
> WIRE -224 400 -224 -16
> WIRE -224 400 -416 400
> WIRE 160 432 -16 432
> WIRE 320 432 896 16
> WIRE 320 432 160 432
> WIRE -576 448 -576 400
> WIRE -416 448 -416 400
> WIRE 160 496 160 432
> WIRE 1472 512 1472 384
> WIRE 1600 512 1600 384
> WIRE 896 528 896 384
> WIRE 544 560 544 384
> WIRE 544 560 320 560
> WIRE -576 576 -576 528
> WIRE -416 576 -416 528
> WIRE -16 608 -16 432
> WIRE 160 608 160 560
> WIRE 160 608 -16 608
> WIRE 256 608 160 608
> WIRE 1472 704 1472 576
> WIRE 1600 704 1600 592
> WIRE -16 784 -16 608
> WIRE 896 784 320 336
> WIRE 896 784 896 608
> WIRE -224 864 -224 400
> WIRE -64 864 -224 864
> WIRE 896 912 896 784
> WIRE -16 960 -16 880
> WIRE 624 960 -16 960
> WIRE 704 960 624 960
> WIRE 832 960 768 960
> WIRE -16 1008 -16 960
> WIRE 624 1072 624 960
> WIRE 320 1120 320 656
> WIRE 480 1120 320 1120
> WIRE 560 1120 480 1120
> WIRE -16 1152 -16 1088
> WIRE 144 1152 -16 1152
> WIRE -16 1216 -16 1152
> WIRE 320 1216 320 1120
> WIRE 144 1232 144 1152
> WIRE 480 1232 480 1120
> WIRE -16 1360 -16 1296
> WIRE 144 1360 144 1296
> WIRE 144 1360 -16 1360
> WIRE 320 1360 320 1296
> WIRE 320 1360 144 1360
> WIRE 480 1360 480 1296
> WIRE 480 1360 320 1360
> WIRE 624 1360 624 1168
> WIRE 624 1360 480 1360
> WIRE 896 1360 896 1008
> WIRE 896 1360 624 1360
> WIRE -16 1472 -16 1360
> FLAG 1696 384 Out
> IOPIN 1696 384 Out
> FLAG -16 1472 Vee
> FLAG -16 -672 Vcc
> FLAG -688 32 0
> FLAG -576 -144 Vcc
> FLAG -576 144 Vee
> FLAG -416 576 0
> FLAG -576 576 0
> FLAG 1472 704 0
> FLAG 1600 704 0
> SYMBOL npn 832 -160 R0
> WINDOW 3 67 65 Left 2
> SYMATTR Value 2SCR514P
> SYMATTR InstName Q1
> SYMBOL pnp 832 1008 M180
> SYMATTR InstName Q2
> SYMATTR Value 2SAR514P
> SYMBOL res 880 160 R0
> SYMATTR InstName R1
> SYMATTR Value 10
> SYMBOL res 880 512 R0
> SYMATTR InstName R2
> SYMATTR Value 10
> SYMBOL nmos -64 784 R0
> SYMATTR InstName M1
> SYMATTR Value RHP030N03
> SYMBOL pmos -64 64 M180
> SYMATTR InstName M2
> SYMATTR Value RRS100P03
> SYMBOL res -32 1200 R0
> SYMATTR InstName R3
> SYMATTR Value 47k
> SYMBOL res -32 -496 R0
> SYMATTR InstName R4
> SYMATTR Value 47k
> SYMBOL voltage -576 -128 R0
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR InstName V1
> SYMATTR Value 5
> SYMBOL voltage -576 0 R0
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR InstName V2
> SYMATTR Value 5
> SYMBOL res -432 432 R0
> SYMATTR InstName R5
> SYMATTR Value 100k
> SYMBOL voltage -576 432 R0
> WINDOW 3 -190 227 Left 2
> WINDOW 123 0 0 Left 2
> WINDOW 39 0 0 Left 2
> SYMATTR Value PULSE(-3 3 0 0.1n 0.1n 5n 10n)
> SYMATTR InstName V3
> SYMBOL res 1088 368 R90
> WINDOW 0 0 56 VBottom 2
> WINDOW 3 32 56 VTop 2
> SYMATTR InstName R6
> SYMATTR Value 50
> SYMBOL cap 1456 512 R0
> SYMATTR InstName C1
> SYMATTR Value 100p
> SYMBOL ind 1248 368 R90
> WINDOW 0 5 56 VBottom 2
> WINDOW 3 59 53 VTop 2
> SYMATTR InstName L1
> SYMATTR Value 100nH
> SYMBOL res 1584 496 R0
> SYMATTR InstName R7
> SYMATTR Value 50
> SYMBOL res 1408 368 R90
> WINDOW 0 0 56 VBottom 2
> WINDOW 3 32 56 VTop 2
> SYMATTR InstName R8
> SYMATTR Value 1
> SYMBOL pnp 256 656 M180
> SYMATTR InstName Q3
> SYMATTR Value 2N3906
> SYMBOL npn 256 96 R0
> SYMATTR InstName Q4
> SYMATTR Value 2N3904
> SYMBOL res 304 -496 R0
> SYMATTR InstName R9
> SYMATTR Value 100
> SYMBOL pnp 560 -256 M180
> SYMATTR InstName Q5
> SYMATTR Value 2N3906
> SYMBOL npn 560 1072 R0
> SYMATTR InstName Q6
> SYMATTR Value 2N3904
> SYMBOL res 304 1200 R0
> SYMATTR InstName R10
> SYMATTR Value 100
> SYMBOL schottky 144 208 R0
> SYMATTR InstName D1
> SYMATTR Value BAT54
> SYMATTR Description Diode
> SYMATTR Type diode
> SYMBOL diode 496 -400 R180
> WINDOW 0 24 64 Left 2
> WINDOW 3 24 0 Left 2
> SYMATTR InstName D4
> SYMATTR Value RF05VA1S
> SYMBOL res -32 -272 R0
> SYMATTR InstName R11
> SYMATTR Value 4.7k
> SYMBOL cap 144 -464 R0
> SYMATTR InstName C2
> SYMATTR Value 5p
> SYMBOL res -32 992 R0
> SYMATTR InstName R12
> SYMATTR Value 4.7k
> SYMBOL cap 128 1232 R0
> SYMATTR InstName C3
> SYMATTR Value 5p
> SYMBOL FerriteBead 736 960 R90
> WINDOW 0 -16 0 VBottom 2
> SYMATTR InstName L3
> SYMATTR Value 22n
> SYMATTR SpiceLine Ipk=0.5 Rser=0.044 Rpar=13 Cpar=1.6p mfg="Wurth 
> Elektronik" pn="742 792 711 0"
> SYMBOL FerriteBead 736 -112 R90
> WINDOW 0 -16 0 VBottom 2
> SYMATTR InstName L2
> SYMATTR Value 22n
> SYMATTR SpiceLine Ipk=0.5 Rser=0.044 Rpar=13 Cpar=1.6p mfg="Wurth 
> Elektronik" pn="742 792 711 0"
> SYMBOL diode 496 1296 R180
> WINDOW 0 24 64 Left 2
> WINDOW 3 24 0 Left 2
> SYMATTR InstName D3
> SYMATTR Value RF05VA1S
> SYMBOL schottky 176 560 R180
> WINDOW 0 24 64 Left 2
> WINDOW 3 24 0 Left 2
> SYMATTR InstName D2
> SYMATTR Value BAT54
> SYMATTR Description Diode
> SYMATTR Type diode
> TEXT -688 704 Left 2 !.tran 800u 

On a sunny day (Mon, 15 May 2017 19:45:04 GMT) it happened Steve Wilson
<no@spam.com> wrote in <XnsA776A03A13A6Cidtokenpost@69.16.179.22>:

>Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote:
>
>> On a sunny day (Mon, 15 May 2017 18:07:57 GMT) it happened Steve Wilson
>> <no@spam.com> wrote in <XnsA7768FC3A2F00idtokenpost@69.16.179.23>:
>>>These issues would be immediately apparent in a proper LTspice 
>analysis.
>>>
>>>Unfortunately, with some users still devoted to ASCII-art or hand-drawn 
>>>schematics, it is difficult or impossible to do a reasonable 
>preliminary 
>>>analysis. 
>> 
>> Man you are way way out in the boonies,
>> 
>> I can tell from just a few strokes if it wrks or not,
>> Van Gogh could too.
>> [My]Tronix is art, you are no art knower, just a wall painter using 
>spice
>> as paintbrush.
>> ;-)
>> 
>> THIS is why US can no longer send humming beans to space,
>> You live in a virtual world.
>> Its all over.
>> The Matrix has you, no way back.
>> ....
>
>I am retired, so I am not so interested in hiring new enginers. If I 
>were, I would use LTspice. SPICE has a huge learning curve that goes on 
>forever. If a candidate cannot use LTspice, he is of no use to me.
>
>You cannot tell if a circuit will work by looking at it. You have to find 
>a way to analyze it that is faster than pencil and paper. The old hybrid-
>pi models are useless to see if a circuit is usable. Unfortunately, these 
>are stiil taught in engineering schools.
>
>My criteria for hiring a new employee would be to show how they are able 
>to construct simple circuits in LTspice and show how they work. If they 
>cannot do that, they are of very little use to me.
>
>Your claim that you can tell if a circuit works by simply looking at it 
>is feeble. You need to prove it works, and LTspice is the best way to 
>start.

Hey, I am retired myself, so some time to play with stuff.
There is such a thing as 'experience', I have seen thousands and thousands circuits,
I have had to repair those too at times, I have a pretty good feel what fails and what does not.
I did both design and repair of stuff, including very high end stuff from media to mil to science.
To 'prove' something works there is only reality.

I do not give a <...> if you (mathematically) prove say a wormhole to me (people do),
but if I can buy it and travel through it and can come back to tell,
I won't ask my money back.

Hiring interviews is always interesting, there are often other forces than tech at work,
say discrimination, personal preferences, friends of somebody... politics.
Then, simple relay driver one transistor, forget the diode...
I had a repair shop, let them repair a set.

In show business there is 'the show must go on' you have to know the stuff in depth,
enough to improvise and invent on the spot or fault find in 1 minute in equipment most here never even 
could fathom in 10 years of study.
And, with electronics, things are always in motion, you study forever,
[LT]spice is just a small niche in it all, toy basically.
The human neural net configuration and weights is where it really is, that is why it is different for everybody.
Until the day we can transfer that neural net configuration and weights, teh new kids on teh block
will have to start again from scratch.
But now they chase Pokemon and want Python...

OK.
And Dinos are no more either.
You gotta give it to the last Dino, if he had a good time he was doing OK.

On Tue, 16 May 2017 03:29:30 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>This was fun. Not bad for 3904s.
>https://www.seventransistorlabs.com/Images/High_Speed_Buffer.png
>See how it works with 10GHz transistors. :^)
>
>Tim

You have almost built an opamp!


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

On a sunny day (Tue, 16 May 2017 03:29:30 -0500) it happened "Tim Williams"
<tiwill@seventransistorlabs.com> wrote in <ofed2o$7nr$1@dont-email.me>:

>This was fun. Not bad for 3904s.
>https://www.seventransistorlabs.com/Images/High_Speed_Buffer.png
>See how it works with 10GHz transistors. :^)

That is a classic.

On Tue, 16 May 2017 01:22:14 GMT, Steve Wilson <no@spam.com> wrote:

>John Larkin <jjlarkin@highland_snip_technology.com> wrote:
>
>> On Mon, 15 May 2017 21:00:54 GMT, Steve Wilson <no@spam.com> wrote:
> 
>>>John Larkin <jjlarkin@highland_snip_technology.com> wrote:
>
>>>> On Mon, 15 May 2017 20:46:14 GMT, Steve Wilson <no@spam.com> wrote:
> 
>>>>>John Larkin <jjlarkin@highland_snip_technology.com> wrote:
>
>>>>>> The current probe is twitchy. I like to add visible current-shunt
>>>>>> resistors to make it easier to probe. 
> 
>>>>>Nothing wrong with that, except you have to add separate node names 
>to
>>>>>either side of the resistor. Then instead of plotting Ib(Q2) you will
>>>>>plot I(R12). The polarity will depend on the orientation of the
>>>>>resistor. 
> 
>>>> LT Spice defaults to getting that backwards.
>
>>>So plot the twitchy base, emitter or collector current, and add a minus 
>>>sign if needed to make it correspond with the waveform.
> 
>> I just flip the resistor.
> 
>As above. Now you are plotting I(Rxx) instead of IB(Qx). Rxx may be a lot 
>harder to find on the schematic than Qx. Wases your time looking.

The resistor is right at the base of the transistor. It's hard to
miss.

>
>Also the extra part takes up more space and requires another node name so 
>you are not trying to plot V(n00x), which may change as soon as you add 
>or remove another node. Good luck trying to find the original node that 
>you wanted to plot. Wastes your time looking.

Node names are free in LT Spice. I name them something meaningful if I
want to see the node name on a plot or a DC analysis. I can name the
resistor RbQ2 or something, too.

>
>There are cases where an extra resistor is actually needed, such as a 
>base parasitic resistor or in the gate of a fast MOSFET. These can remind 
>you to include the resistor in the pcb layout, and help determine the 
>value needed in the circuit.


I'm not likely to forget, but Spice is useless in determining the
value that will kill oscillations. It can establish that some value
won't slow down normal operation too much. I tend to use 33 ohms.


-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

On a sunny day (Tue, 16 May 2017 08:12:13 GMT) it happened Jan Panteltje
<pNa0nStpealmtje@yahoo.com> wrote in <ofec8t$1a9r$1@gioia.aioe.org>:

><bitrex@de.lete.earthlink.net> wrote in <zsnSA.28967$9o7.3799@fx12.iad>:

>>Yes, the basic topology is an _excellent_ performer at low quiescent 
>>bias current, low frequency, and into no load! ;-)
>
>Na, be a good sport, if I have time tonight I will add a 75 Ohm load,
>and rebuild it so the driver PNP is making thermal contact with the output NPN (for each half).
>I hope that will fix any thermal tracking.
>The above setup I build faster than you spicers could enter it.
>AND it is real, unlike in the matrix.. 
>;-)

So....
been doing some testing, 75 Ohm load:
 http://panteltje.com/pub/some_detail_IMG_6194.JPG

  2 signal sources, laptop 20 kHz and 60 MHz square wave oscillator module (on small PCB borrowed from other HF project).
  output loaded with 75 Ohm coupled with a capacitor as I am testing with single rail lab supply between 5 and 10V.
  and I decoupled the supply line too this time.

20 kHz in 75 Ohm:
 http://panteltje.com/pub/input_output_20kHz_75_Ohm_load_IMG_6193.JPG
  input and output guess who is who (I know).

Since I do not have one of those defective scopes, the ones that only work every now and then,
sometimes call 'sampling scopes [1]' by their users, I use a trick 
 http://panteltje.com/pub/60MHz_square_wave_in_antenna_out_plus_75Ohm_load_IMG_6192.JPG
send the output to a piece of wire, and via LAN start raspberry that has antenna in attic sdr_rtl and my spectrum analyzer (I wrote it)

to see what comes out as harmonics.... of the 60 MHz square wave I feed in:
 http://panteltje.com/pub/testing_second_harmonic_of_60MHz_squarewave_IMG_6191.JPG
base at 60 MHz, second at 120 MHz, third at 180 MHz and a weak fourth at 240 MHz no problem finding with sdr gain at minimum.

Hope this helps.

Any more questions please build it yerself, it is not that hard.

Thermal runaway? No sign of it, not with these voltages and 75 Ohm load.
So .. else glue some trannies together so they track.
nuf said.

[1] I do have one but it is slow:
 http://panteltje.com/panteltje/pic/scope_pic/