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Old 22nd June 2010, 07:58 PM   #1
larryB is offline larryB  Canada
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Do not read this thread if you are not gonna comment . Do not criticize unless you have valuable info or advice or schematic to go along with your critique .

Here are some observations/simulatins from my circuit design , I just wanna make an power amplifier that can handle reactive loads and stay sine , maybe with a little power with that , a capable sine wave oscillator if you will , for tesla experimets . So I am a bit going blind here since my load is a total mystery , I guess the transformer needs to be matched to the still undiscovered load , Or maybe I will go for a one size fits all impedance bridging transformer instead , is there such a thing as a low impedance transformer with Ok coupling factor ?

Anyways , these simulations are crap , there is no good transformer with center tap with this free-version multisim from a book , all secondaries are messed up , its as if this was meant for tubes , I dont know much about these transformers . I am aware of the forumula for a voltage drop across a component is = current squares * impedance .

As you can see , my self-made circuit topology actually works , loves resonant loads and inductive loads , large capacitance not so good , still gives a tiny amplitude sine after a bit settling time , I guess the lower the secondary impedance the better it is for capacitive loads ? It seems to be quite similar to the single ended in terms of various reactive loads besides the tiny little distortion , to me that is very acceptable . I think I will go with my design after all and start designing a pcb , I like the simplicity of it , I like the adjustable biasing on both legs , I like the direct coupling and the simple power supply . If you notice the npn voltage follower this stage might not be used , its just to isolate capacitive loads and make the op amps job easier . Modern op amps are good enough I think , I dont believe these people that say many active components = bad , I am eyeing up a particular op amp , the tle2142 . -1 gain stable , very fast settling , very fast slew rate , high output swing , very low offset voltage , low noise . Cheap and available in 4 channel version so the voltage gain and rectifier can be on the same chip for best matching possible , good for +- 18 volt rail and compensated for capacitive loads .. My power supply will be a +-18 volt regulated supply with an oversized positive rail . Mosfets will run on battery power or a 15 volt power supply . Hope this is high enough to eliminate gate oscillation with the lateral mosfets .

Precision Amplifier - Wide Bandwidth - TLE2144A - TI.com

Here are some simulations , obervation , circuit waveforms . Might seem noobish but heh ... All these were taken at 20 khz ... Maybe somebody can answer these little question and observations I put there

Comments are very welcomed . Do not read this thread anymore if you are not gonna comment
Attached Images
File Type: jpg directshort.JPG (137.7 KB, 175 views)
File Type: jpg inductiveload.JPG (220.3 KB, 172 views)
File Type: jpg largecapacitiveload.JPG (306.5 KB, 159 views)
File Type: jpg mydesign.JPG (257.5 KB, 150 views)
File Type: jpg semi-resonant.JPG (195.8 KB, 139 views)
File Type: jpg single-ended.JPG (263.2 KB, 29 views)
File Type: jpg untitled43.JPG (78.0 KB, 71 views)

Last edited by larryB; 22nd June 2010 at 08:27 PM.
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Old 22nd June 2010, 11:32 PM   #2
larryB is offline larryB  Canada
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82 people read this post and didnt reply , most of them have small wieners and bad haircuts . ( he who replies about this sentence and not about general electronics is as described in this sentence )

Here is my idea , I like this better than the zeus if the only disadvantage is the slight distortion , wich is more like an acceleration , not at all a crossover distortion . The idea is basicly a halfwave biased in continous conduction to avoid bemf issues and kinks , simple as that . If you know how to make a half wave biased with another technique plz do share .

Looking from the basic superposition of the waveforms of same peak amplitude and same bias current , my technique looks/is more efficient . Also , it does not suffer from bad efficiency at lower amplitude . As you can see from the very basic pictures .

So to the experts , lets start a debate about this with passionate opinions , I am wondering what is the difference between the 2 techniques , they both give the same output at the secondary , one has a slight distortion , one has bad efficiency . But wich one is the best @ being stable with all kinds of reactive loads . What is YOUR opinion ?
Attached Images
File Type: jpg zeuscompare.JPG (199.4 KB, 52 views)
File Type: jpg powercompare.JPG (136.1 KB, 24 views)

Last edited by larryB; 22nd June 2010 at 11:55 PM.
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Old 23rd June 2010, 12:19 AM   #3
T in AZ is offline T in AZ  United States
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Build it, looks like you've simmed it to the point that you need to see what it does in real time.
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Old 23rd June 2010, 01:07 AM   #4
larryB is offline larryB  Canada
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Thx you for the comment , you have given me confidence .

Yes I am making this on a pcb , my design and a zeus like to see wich comes out on top .

I have a bunch of crazy oscillators I made I wanna try out with power , learning amplifier basics was harder than expected yet I have much experience @ imaginating circuits only not the right knowledge for applying the math to actually finish the things I make , I actually invented a massive 3 channel harmonics phase shift pure oscillator that is 100% stable . Using the appropriate analog logic that I invented with a ramp wave and comparators I created this I can make a 0-2 Khz phase shift pure sine oscillator that has no jitter and phasing issues that I can adjust with a single pot phase or amplitude . I have also built a self-made 3 wave mixer , a self-made 3 phase driver using only cmos .

Last edited by larryB; 23rd June 2010 at 01:12 AM.
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Old 23rd June 2010, 02:26 AM   #5
sawreyrw is offline sawreyrw  United States
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Your schemetics are almost impossible to read. If I could read them, I might comment; just thought you might like to know this.
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Old 23rd June 2010, 03:01 AM   #6
larryB is offline larryB  Canada
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the schematic is called untitled43 , in my sim I have omitted a few things from that design for simplicity reasons , there is no npn voltage follower as well . All the chaotic sim schematics with diodes in em are the design mentionned with different loads .

The other schematics are very simple , there is nothing to see there .

Last edited by larryB; 23rd June 2010 at 03:18 AM.
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Old 23rd June 2010, 09:32 AM   #7
godfrey is offline godfrey  South Africa
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Location: Cape Town
Maybe something like this would be good?

The bias for the two Mosfets can be set with VR1 and VR2.
R1 is to reduce feedback around U1 so it's speed matches U2.
Supply for the op-amps is +-24V (not shown).

Cheers - Godfrey
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File Type: gif weird.GIF (4.3 KB, 43 views)
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