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A relatively unimportant announcement...

Discussion in 'Electronic Design' started by Paul Burridge, Dec 24, 2003.

  1. James Meyer

    James Meyer Guest

    OK Paul. Would you like to put your money where your mouth is? You
    name the stakes and we'll let Win Hill hold the purse.

    My bet is that you'll never get it to work worth a darn with only one
    diode in there.

    Since I'm laid up at home with a cracked rib and bored as hell, I'm
    going to put your circuit into LTSpice. Then I'm going to add the second diode
    and post the differences.

    Jim Meyer (the other Jim)
     
  2. James Meyer

    James Meyer Guest

    It's at "http://www.burridge8333.fsbusiness.co.uk/fsm(revision1).jpg"

    Be sure to copy the whole URL between the double quote marks and paste
    it into your browser. The brackets confuse my news reader.

    Note to Paul......

    Since LTSpice is freeware and anybody with a windows platform can run
    it, the best way to distribute your simulations is by adding the .asc file to a
    post. The .asc file is plain text and it will recreate the complete schematic
    when you clip it out of a post, paste it into notepad, and save it as as .asc
    file.

    example of hartley.asc from the LTSpice distribution.....

    .......begin copy here....

    Version 4
    SHEET 1 2624 2336
    WIRE 1984 2048 2144 2048
    WIRE 2400 2064 2400 2096
    WIRE 2400 2176 2400 2192
    WIRE 2192 1984 2192 1968
    WIRE 2192 1968 2320 1968
    WIRE 2400 1984 2400 1968
    WIRE 2080 1920 1984 1920
    WIRE 1984 1920 1984 1792
    WIRE 1984 1792 2000 1792
    WIRE 2080 1792 2112 1792
    WIRE 2224 1792 2256 1792
    WIRE 2320 1936 2320 1968
    WIRE 2320 1968 2400 1968
    WIRE 2144 1920 2256 1920
    WIRE 2256 1920 2256 1856
    WIRE 2320 1856 2256 1856
    WIRE 2256 1856 2256 1792
    WIRE 2320 1856 2320 1872
    WIRE 2112 1792 2112 1824
    WIRE 2112 1792 2144 1792
    WIRE 1984 1952 1984 1920
    WIRE 1984 2016 1984 2048
    WIRE 1984 2096 1984 2048
    WIRE 1984 2160 1984 2192
    WIRE 2192 2080 2192 2192
    WIRE 2160 1664 2400 1664
    WIRE 2080 1664 1984 1664
    FLAG 2400 2192 GND
    FLAG 2192 2192 GND
    FLAG 2112 1824 GND
    FLAG 1984 2192 GND
    FLAG 1984 1664 GND
    FLAG 2400 1664 out
    SYMBOL njf 2144 1984 R0
    SYMATTR InstName J1
    SYMATTR Value 2N5484
    SYMBOL voltage 2400 2080 R0
    SYMATTR InstName V1
    SYMATTR Value 10.
    SYMBOL cap 2144 1904 R90
    WINDOW 0 0 32 VBottom 0
    WINDOW 3 32 32 VTop 0
    SYMATTR InstName C4
    SYMATTR Value 250p
    SYMBOL ind 2384 1968 R0
    WINDOW 0 36 25 Left 0
    WINDOW 3 36 55 Left 0
    WINDOW 39 37 81 Left 0
    SYMATTR InstName L4
    SYMATTR Value 1mH
    SYMATTR SpiceLine Rser=100
    SYMBOL ind2 2128 1808 R270
    WINDOW 0 32 56 VTop 0
    WINDOW 3 4 56 VBottom 0
    SYMATTR InstName L2
    SYMATTR Value 30µ
    SYMBOL ind2 1984 1808 R270
    WINDOW 0 32 56 VTop 0
    WINDOW 3 4 56 VBottom 0
    SYMATTR InstName L1
    SYMATTR Value 30µ
    SYMBOL cap 2304 1872 R0
    SYMATTR InstName C1
    SYMATTR Value 500p
    SYMBOL cap 1968 1952 R0
    SYMATTR InstName C2
    SYMATTR Value 30p
    SYMBOL diode 1968 2160 M180
    WINDOW 0 24 72 Left 0
    WINDOW 3 24 0 Left 0
    SYMATTR InstName D2
    SYMATTR Value 1N4148
    SYMBOL ind2 2064 1680 R270
    WINDOW 0 32 56 VTop 0
    WINDOW 3 4 56 VBottom 0
    SYMATTR InstName L3
    SYMATTR Value 3µ
    TEXT 1912 2248 Left 0 !.tran 250µ startup
    TEXT 2112 1728 Center 0 !K1 L1 L2 L3 1.
    text 1664 2320 Left 0 ;This example schematic is supplied for
    informational/educational purposes only.

    .......end copy here....
     
  3. Jim Thompson

    Jim Thompson Guest

    I only see the schematic there. Was there a posting of *simulation*
    results?

    ...Jim Thompson
     
  4. James Meyer

    James Meyer Guest

    Only the schematic. The results were verbal. Provided by Paul.

    Here's the schematic I reproduced with LTSpice....

    Version 4
    SHEET 1 1864 680
    WIRE 1680 192 1680 384
    WIRE -192 304 -192 384
    WIRE -192 384 0 384
    WIRE 1680 384 1680 416
    WIRE 0 304 0 384
    WIRE 0 384 144 384
    WIRE 144 288 144 384
    WIRE 144 384 320 384
    WIRE 320 320 320 384
    WIRE 320 384 464 384
    WIRE 464 336 464 384
    WIRE 464 384 576 384
    WIRE 576 336 576 384
    WIRE 576 384 720 384
    WIRE 720 320 720 384
    WIRE 720 384 848 384
    WIRE 848 336 848 384
    WIRE 848 384 976 384
    WIRE 976 336 976 384
    WIRE 976 384 1088 384
    WIRE 1088 320 1088 384
    WIRE 1088 384 1200 384
    WIRE 1200 336 1200 384
    WIRE 1200 384 1328 384
    WIRE 1328 336 1328 384
    WIRE 1328 384 1536 384
    WIRE 1536 272 1536 384
    WIRE 1536 384 1680 384
    WIRE 1680 112 1680 -64
    WIRE 1680 -64 1248 -64
    WIRE 320 -64 320 0
    WIRE -192 224 -192 144
    WIRE -192 144 0 144
    WIRE 0 224 0 144
    WIRE 0 144 144 144
    WIRE 144 224 144 144
    WIRE 144 144 192 144
    WIRE 320 240 320 144
    WIRE 288 144 320 144
    WIRE 320 144 320 80
    WIRE 400 144 320 144
    WIRE 464 96 512 96
    WIRE 512 64 512 96
    WIRE 512 96 576 96
    WIRE 512 -16 512 -64
    WIRE 512 -64 320 -64
    WIRE 576 272 576 224
    WIRE 576 224 464 224
    WIRE 464 224 464 192
    WIRE 464 256 464 224
    WIRE 672 96 720 96
    WIRE 720 96 720 64
    WIRE 720 96 720 144
    WIRE 784 144 720 144
    WIRE 720 144 720 240
    WIRE 720 -16 720 -64
    WIRE 720 -64 512 -64
    WIRE 896 -64 896 -16
    WIRE 896 -64 720 -64
    WIRE 960 96 944 96
    WIRE 896 64 896 96
    WIRE 896 96 848 96
    WIRE 848 256 848 224
    WIRE 848 224 976 224
    WIRE 976 224 976 272
    WIRE 848 192 848 224
    WIRE 1328 240 1328 272
    WIRE 1200 256 1200 240
    WIRE 1200 240 1328 240
    WIRE 1088 240 1088 144
    WIRE 1088 -16 1088 -64
    WIRE 1088 -64 896 -64
    WIRE 1024 96 1088 96
    WIRE 1088 96 1088 64
    WIRE 1136 144 1088 144
    WIRE 1088 144 1088 96
    WIRE 1312 96 1296 96
    WIRE 1248 96 1248 64
    WIRE 1248 96 1200 96
    WIRE 1248 -16 1248 -64
    WIRE 1248 -64 1088 -64
    WIRE 1376 96 1424 96
    WIRE 1488 96 1520 96
    WIRE 1536 96 1536 192
    WIRE 1680 -64 1808 -64
    WIRE 1808 112 1808 -64
    WIRE 1808 176 1808 384
    WIRE 1808 384 1680 384
    WIRE 1200 192 1200 240
    WIRE 1520 96 1536 96
    WIRE 192 144 224 144
    WIRE 576 96 608 96
    WIRE 944 96 896 96
    WIRE 1296 96 1248 96
    FLAG 1680 416 0
    FLAG 1520 96 OUT
    FLAG 192 144 VIN
    FLAG 576 96 V1
    FLAG 944 96 V2
    FLAG 1296 96 V3
    SYMBOL voltage -192 208 R0
    WINDOW 123 24 132 Left 0
    WINDOW 39 24 160 Left 0
    SYMATTR InstName V1
    SYMATTR Value SINE(0 50e-6 40.5e6)
    SYMATTR Value2 AC 50e-6
    SYMATTR SpiceLine Rser=50
    SYMBOL ind -16 208 R0
    SYMATTR InstName L1
    SYMATTR Value 150e-9
    SYMBOL cap 128 224 R0
    SYMATTR InstName C1
    SYMATTR Value 79e-12
    SYMBOL cap 288 128 R90
    WINDOW 0 0 32 VBottom 0
    WINDOW 3 32 32 VTop 0
    SYMATTR InstName C2
    SYMATTR Value 10n
    SYMBOL res 304 -16 R0
    SYMATTR InstName R1
    SYMATTR Value 47K
    SYMBOL res 304 224 R0
    SYMATTR InstName R2
    SYMATTR Value 47K
    SYMBOL npn 400 96 R0
    SYMATTR InstName Q1
    SYMATTR Value 2N3904
    SYMBOL res 448 240 R0
    SYMATTR InstName R3
    SYMATTR Value 3.9K
    SYMBOL cap 560 272 R0
    SYMATTR InstName C3
    SYMATTR Value 10n
    SYMBOL res 496 -32 R0
    SYMATTR InstName R4
    SYMATTR Value 2.7K
    SYMBOL cap 672 80 R90
    WINDOW 0 0 32 VBottom 0
    WINDOW 3 32 32 VTop 0
    SYMATTR InstName C4
    SYMATTR Value 10n
    SYMBOL res 704 -32 R0
    SYMATTR InstName R5
    SYMATTR Value 12K
    SYMBOL res 704 224 R0
    SYMATTR InstName R6
    SYMATTR Value 12K
    SYMBOL npn 784 96 R0
    SYMATTR InstName Q2
    SYMATTR Value 2N3904
    SYMBOL res 880 -32 R0
    SYMATTR InstName R7
    SYMATTR Value 5K
    SYMBOL res 832 240 R0
    SYMATTR InstName R8
    SYMATTR Value 5.3K
    SYMBOL cap 960 272 R0
    SYMATTR InstName C5
    SYMATTR Value 10n
    SYMBOL cap 1024 80 R90
    WINDOW 0 0 32 VBottom 0
    WINDOW 3 32 32 VTop 0
    SYMATTR InstName C6
    SYMATTR Value 10n
    SYMBOL res 1072 -32 R0
    SYMATTR InstName R9
    SYMATTR Value 9K
    SYMBOL res 1072 224 R0
    SYMATTR InstName R10
    SYMATTR Value 3K
    SYMBOL npn 1136 96 R0
    SYMATTR InstName Q3
    SYMATTR Value 2N3904
    SYMBOL res 1232 -32 R0
    SYMATTR InstName R11
    SYMATTR Value 3.9K
    SYMBOL res 1184 240 R0
    SYMATTR InstName R12
    SYMATTR Value 130
    SYMBOL cap 1312 272 R0
    SYMATTR InstName C7
    SYMATTR Value 10n
    SYMBOL cap 1376 80 R90
    WINDOW 0 0 32 VBottom 0
    WINDOW 3 32 32 VTop 0
    SYMATTR InstName C8
    SYMATTR Value 10n
    SYMBOL schottky 1424 112 R270
    WINDOW 0 32 32 VTop 0
    WINDOW 3 0 32 VBottom 0
    SYMATTR InstName D1
    SYMATTR Value 1N5818
    SYMATTR Description Diode
    SYMATTR Type diode
    SYMBOL res 1520 176 R0
    SYMATTR InstName R13
    SYMATTR Value 390
    SYMBOL voltage 1680 96 R0
    WINDOW 123 0 0 Left 0
    WINDOW 39 0 0 Left 0
    SYMATTR InstName V2
    SYMATTR Value 12
    SYMBOL cap 1792 112 R0
    SYMATTR InstName C9
    SYMATTR Value 10n
    TEXT 568 456 Left 0 !.ac oct 10 10E6 100E6
    TEXT 560 424 Left 0 !;tran 0 25E-6 24E-6

    ............

    I ran the simulation and adjusted the LC values to put the input a
    little closer to 40.5MHz and got 33 microvolts at the output for 50 microvolts
    in. There was more RF at the collector of the first transistor, but it kept
    going down instead of up with each succeeding stage.

    The number of diodes is moot until there's enough RF at the output to
    turn one on.

    Jim
     
  5. [...]

    James, our simulations clearly don't agree so I need to get this list
    you've posted into LT at this end and establish the differences. So
    how do I do that? None of my LT files resemble the list you've posted
    in any way.
     
  6. James Meyer

    James Meyer Guest

    The file "fsm.asc" is the schematic file you created on your machine.

    Look at that file with something like notepad or some other word
    processor.

    Use your mouse to highlight the part of my message that starts with
    "Version 4" and continues through "TEXT 560 424 Left 0 !;tran 0 25E-6 24E-6".

    Hit <ctrl><C> to copy that part into the clipboard.

    Open notepad with a blank file and hit <ctrl><V> to paste the clipboard
    contents into the blank file.

    Use the menu to "save as.." some filename with a ".asc" extension.

    Then go to LTSpice and open the file you just saved.

    Jim
     
  7. Thanks, James, I'll try that. In the mean time, the result of my own
    sim can now be view at this page:

    http://www.burridge8333.fsbusiness.co.uk/plot.gif

    And before anyone says anything; I have run this to 15mS and the o/put
    stays at the same level.
     
  8. Baphomet

    Baphomet Guest

    In looking at your simulation, I'm seeing about 10mvpp (centered around 0v.)
    How will your D.C. microammeter respond to this A.C. signal?
     
  9. Sorry. Doesn't add up. If you mean the spice *netlist* then this is
    it:

    * C:\Program Files\LTC\SwCADIII\fieldstrengthmeter.asc
    L1 N004 0 180n Rser=10
    C1 N004 0 87p
    R1 N005 N001 47k
    R2 N001 0 47k
    R3 N003 0 3.9k
    R4 N005 N002 2.7k
    Q1 N002 N001 N003 0 2N3904
    C2 N003 0 10n
    V1 N005 0 12
    V2 N004 0 SINE(0 50u 40.5e6) Rser=50
    C5 N004 N001 10n
    Q2 N012 N011 N006 0 2N3904
    R6 N011 0 3k
    R7 N006 0 1300
    R8 N007 0 380
    C3 N008 N002 10n
    Q3 N009 N008 N010 0 2N3904
    R5 N005 N008 12k
    R9 N008 0 12k
    C6 N010 0 10n
    R10 N010 0 5.3k
    R11 N005 N009 5k
    C7 N009 N011 10n
    R12 N005 N011 9k
    R13 N005 N012 3.9k
    C4 N006 0 10n
    C8 N005 0 0.01µ
    C10 N013 N012 10n
    D1 N013 N007 1N5819
    ..model D D
    ..lib C:\Program Files\LTC\SwCADIII\lib\cmp\standard.dio
    ..model NPN NPN
    ..model PNP PNP
    ..lib C:\Program Files\LTC\SwCADIII\lib\cmp\standard.bjt
    ..tran 0 1m 0 10n
    * .op
    ;tran 0 1m 0 10n
    ;op
    ;ac lin 500 39e6 42e6
    ..backanno
    ..end

    and it's nothing like your list in format. I doubt LT would even
    recognise it. Which version are you using?
     
  10. Oh Christ I hadn't thought of that. Shit!
     
  11. Baphomet

    Baphomet Guest

    Happy holidays. Correcting this will make a good Christmas project ;-)
    Winston Churchill
     
  12. James Meyer

    James Meyer Guest

    Sorry about the transient simulation message I made earlier.

    If you look at your plot output, you'll see that there is no sign of any
    DC offset to the RF voltage. You need DC to make the meter pointer move.

    And the other Jim showed you that even with many volts of RF available
    at the output of your amplifier, that there still won't be any DC generated to
    move the pointer.

    You've got two problems:

    The first is that the 2N3904 is too slow to make an RC coupled RF
    amplifier at 40 MHz.

    The second is the RF to DC conversion problem between the amp and the
    meter.

    Jim
     
  13. James Meyer wrote:
    (snip)
    I played around with the simulator, last night, and was able to get a
    voltage gain of about 2 with the 2N3904 common emitter at 40 MHz with
    an source impedance about twice the collector resistor. Pretty lame.
    But I did a bit better (more than 4) with a cascode arrangement. I
    may try to see what I can do with an emitter follower on input and
    output (4 transistors, total). The low input impedance of the common
    emitter stage at 40 MHz is what really bites when you are trying to
    get both voltage and current gain, unless you can tune the capacitance
    out with inductance, but then you get a narrow band amplifier and a
    big tendency to oscillate.

    (snip)
     
  14. John Larkin

    John Larkin Guest

    Third: a reasonably short 40 MHz antenna will be nothing like a 50 ohm
    source.

    Fourth: a 1N5819 is a power diode; it has *lots* of capacitance. And
    the meter movement will have lots of inductance.

    Fifth: the DC biasing is weird, with the middle stage almost
    saturated. This will cost GBW.

    John
     
  15. Jim Thompson

    Jim Thompson Guest

    You are correct "the o/put stays at the same level"... average value =
    ZERO!

    ROTFLMAO!

    ...Jim Thompson
     
  16. I guess not. But I did build a first version with only one voltage
    ampilifier stage followed by an emitter follower and it worked like a
    charm *even with the capacitively-coupled diode* - but only at a
    distance of a few feet from the tx.
    Whatever. I'm going to use a germanium (low barrier-height) detector
    job like an OA90 in the real circuit so it won't matter.
    GBW? What's that?
     
  17. Yes, I know what you're going to say to this, so don't bother. I've
    checked that possibility.
     
  18. Yeah, well it's the *peak* value we're concerned with here. ;-)
     
  19. Jim Thompson

    Jim Thompson Guest

    Paul, Please explain to the group *how* this waveform influences a
    meter?

    ...Jim Thompson
     
  20. John Larkin

    John Larkin Guest

    I you will now kindly un-nail my ass from the wall, I can go about my
    business.

    John
     
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