Fun And Games With Spice
- Mike H
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#92
Slight detour ~ the standard LTspice generic simple op-amp model. Slight problem in that the output is fixedly referenced to ground (node 0)
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- Simple Op-amp model
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- The simple op-amp symbol
- generic_opamp1.gif (2.13 KiB) Viewed 5402 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#93
No, it doesn't make any difference where the bottom of the G element is connected! Still works even if + input is DC offset
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#95
Oh alright then here's a quick picture
Tried to get the dynamic impedance at 160k or near enough according to data sheet (@ 300R bias, 10mA), hence the slopes. Which we actually want else it won't work as a load
Resistance steps 30 - 3300R by octaves
Tried to get the dynamic impedance at 160k or near enough according to data sheet (@ 300R bias, 10mA), hence the slopes. Which we actually want else it won't work as a load
Resistance steps 30 - 3300R by octaves
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- 10m45s-sweep-1.gif (6.45 KiB) Viewed 5367 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#98
Basic block diagram, doesn't actually look like this but this is the prinicple
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"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#99
It do am ack-cherley looks like this:
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- 10m45s-block2.gif (7.31 KiB) Viewed 5333 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#100
Test #1 ~ 6SL7
DC = 1.4mA.
Using another 6SL7 for the CCS, gain is 43 plus some fraction.
Using 10M45S model, gain is 60.5.
The dynamic resistance is Volts change divided by current change is that right?
If so I make it a shade over 320k
DC = 1.4mA.
Using another 6SL7 for the CCS, gain is 43 plus some fraction.
Using 10M45S model, gain is 60.5.
The dynamic resistance is Volts change divided by current change is that right?
If so I make it a shade over 320k
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- 10m45s-test1.gif (5.17 KiB) Viewed 5325 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#101
Edited
Using the 6SL7 CCS, the positive tips of the waveform were begining to round off very slightly. With this they don't:
Using the 6SL7 CCS, the positive tips of the waveform were begining to round off very slightly. With this they don't:
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- 10m45s-plot1.gif (8.98 KiB) Viewed 5323 times
Last edited by Mike H on Wed Apr 28, 2010 3:52 pm, edited 1 time in total.
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
#102
Are you measuring this with the 470k resistor in parallel with the CCS?The dynamic resistance is Volts change divided by current change is that right?
If so I make it a shade over 320k
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- Mike H
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#103
Test #2 ~ 1kHz square wave, 1uS rise and fall times.
The spikes at the bottom are something to do with the input not the output.
The spikes at the bottom are something to do with the input not the output.
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- 10m45s-plot2.gif (7.83 KiB) Viewed 5318 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#104
Since you mention it yes. So probably considerably more, data sheet does say can be up to 900kNick wrote:Are you measuring this with the 470k resistor in parallel with the CCS?
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
- Mike H
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#105
Test #3 ~ source follower output
Gain is up to 66.66, and maintains it into a 100k load on the output.
Gain is up to 66.66, and maintains it into a 100k load on the output.
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- 10m45s-plot3.gif (9.31 KiB) Viewed 5314 times
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- 10m45s-test3.gif (5.35 KiB) Viewed 5314 times
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."