On a sunny day (Mon, 15 May 2017 17:18:17 GMT) it happened Steve Wilson wrote in :
Well OK, it is BC547-B / BC557-B (B is the beta range) Sometimes I wonder what sort of monitor or viewer people use...
It may be that in some cases LTspice can not do my circuits :-)
On a sunny day (Mon, 15 May 2017 13:30:20 -0400) it happened bitrex wrote in :
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.
On a sunny day (Mon, 15 May 2017 18:07:57 GMT) it happened Steve Wilson wrote in :
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. ....
On a sunny day (Mon, 15 May 2017 19:50:40 +0100) it happened "Kevin Aylward" wrote in :
Hi Kevin, just wanted to ask, I was following some public lectures by several professors last week, and the last one was about the Higgs boson. In that space is not empty and filled with the Higgs field. Today I have been studying that stuff.. and found some interesting mass related problems. Did you have thoughts about that?
Ever met the man?
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"
Yes, the basic topology is an _excellent_ performer at low quiescent bias current, low frequency, and into no load! ;-)
analysis.
preliminary
spice
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.
LT has a transmission line. It's fully symmetric, like an unshielded twisted pair. And it acts as if it has an ideal transformer inside; it tolerates any common-mode difference between ends. In fact, it makes a handy ideal transformer.
To simulate an actual twisted pair, I use three of the LT Spice TXLINE things.
Probably the middle one should have a different prop delay.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
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. This is not so bad, except you will have to turn it around to get the flow in the direction you want. Or you could simply add a minus sign to the plot to get it to the direction you want.
These are simple things, but are part of the huge learning curve in spice.
This is why I wish people would post working LTspice schematics instead of ASCII or hand-drawn schematics that most likely do not function.
If you are speaking of the complmentary emitter-follower circuit, it is not new. I used it in 1979 and shipped it in millions of dollars worth of products in 1980's dollars.
HP thought it was excellent, which led to several hundred thousand dollar sales.
I don't know if it has a name, but it is also shown in numerous web sites today.
LT Spice defaults to getting that backwards.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
So plot the twitchy base, emitter or collector current, and add a minus sign if needed to make it correspond with the waveform.
No matter how painful or inconvenient, LTspice is still orders of magnitude more useful than ASCII or hand-drawn schematics.
I just flip the resistor.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
to
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 wrote in :
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 wrote in :
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.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:
On a sunny day (Mon, 15 May 2017 19:45:04 GMT) it happened Steve Wilson wrote in :
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.
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" wrote in :
That is a classic.
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