I am not able to properly implement this circuit with 12AX7 tube preamp in LTSPICE. LTSPICE file is attached. Simulation is not giving proper result. Similar circuit with LM317 show correct simulation in LTSPICE. I am trying to learn about use of CCS in tube circuits.
If, in addition to the .asc, you would attach a couple of .png files with your simulation set-up and results, forum members with no access to LTSpice could also try to help spotting anything suspicious.
How do you model the LM334? Could you post a text file of the netlist of the subcircuit you use?
How do you model the LM334? Could you post a text file of the netlist of the subcircuit you use?
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*DN2540 MODEL
*
.MODEL DN2540 NMOS (LEVEL=3 RS=1.05 NSUB=5.0E14
+DELTA=0.1 KAPPA=0.20 TPG=1 CGDO=3.1716E-10
+RD=11 VTO=-1.50 VMAX=1.0E7 ETA=0.0223089
+NFS=6.6E10 TOX=725E-10 LD=1.698E-9 UO=862.425
+XJ=6.4666E-7 THETA=1.0E-5 CGSO=2.50E-9 L=4.0E-6
+W=59E-3)
.ENDS
*
- Generic triode model: 12AX7
- Copyright 2003--2008 by Ayumi Nakabayashi, All rights reserved.
- Version 3.10, Generated on Sat Mar 8 22:41:09 2008
- Plate
- | Grid
- | | Cathode
- | | |
BGG GG 0 V=V(G,K)+0.59836683
BM1 M1 0 V=(0.0017172334*(URAMP(V(A,K))+1e-10))**-0.2685074
BM2 M2 0 V=(0.84817287*(URAMP(V(GG)+URAMP(V(A,K))/88.413802)+1e-10))**1.7685074
BP P 0 V=0.001130216*(URAMP(V(GG)+URAMP(V(A,K))/104.24031)+1e-10)**1.5
BIK IK 0 V=U(V(GG))*V(P)+(1-U(V(GG)))*0.00071211506*V(M1)*V(M2)
BIG IG 0 V=0.000565108*URAMP(V(G,K))*1.5(URAMP(V(G,K))/(URAMP(V(A,K))+URAMP(V(G,K)))*1.2+0.4)
BIAK A K I=URAMP(V(IK,IG)-URAMP(V(IK,IG)-(0.00058141055*URAMP(V(A,K))**1.5)))+1e-10*V(A,K)
BIGK G K I=V(IG)
* CAPS
CGA G A 1.7p
CGK G K 1.6p
CAK A K 0.5p
.ENDS
LM334 symbol and subckt is at link given below.
https://ltwiki.org/files/LTspiceIV/examples/LtSpicePlus/Miscel/LM334 Current Source/
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I see a lot of triple question marks on the schematic. Are you trying to run an operating point analysis, which doesn't converge?
Pictures after running simulation with LM334 and LM317 in same circuit. Only current setting resistor is changed.
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So it's oscillating like crazy and the annotated voltages and currents are either momentary transient values or make no sense at all.
Does it help when you connect the bottom side of C1 to the -ve pin of the LM334 instead of to ground? What happens when you remove C1 and R7 altogether?
Does it help when you connect the bottom side of C1 to the -ve pin of the LM334 instead of to ground? What happens when you remove C1 and R7 altogether?
connect C1 to the -ve pin instead of ground - simulation stuck 00.0%
remove C1 and R7 - nothing happens, oscillations increase.
Something happens when the LM334 is not grounded. The circuit on the left is noisy (green), the one on the right (blue) is clean. Edited to repeat the test with the proper voltage (max 40V)
Removed R2 and connected gate of DN2540 directly to -ve of LM334. The circuit now works but simulation takes lot of time - around 7 minutes.
The simulation did not happen with R2 (100 ohms) in circuit.
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I don't know if this has anything to do with it, but when you look into the LM334 netlist that boetel linked to, the substrate terminals of all transistors are connected to node 0, which is usually ground. In real life they must be connected to the -ve pin of the LM334.
Whether this affects the simulation depends on what the defaults are for substrate diodes in the transistors. At least it doesn't physically make sense.
Five years ago, I built and measured an LM334+cascode CCS circuit. It gave a very "flat" current source, with very low output conductance (g_out := dI_out / dV_out)
LM334 makes quite a nice 5.5 mA current source, works down to 2.0-2.2 volts
Cascoded LM334's also worked quite well in a Front End card for the VFET / Theseus series of Class-A solid state power amps, schematic below.
_
LM334 makes quite a nice 5.5 mA current source, works down to 2.0-2.2 volts
Cascoded LM334's also worked quite well in a Front End card for the VFET / Theseus series of Class-A solid state power amps, schematic below.
_
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No complaints from listeners -- but Hornet's input is 2V RMS, which equals 5.65V peak to trough. So a dozen nanovolts per root Hz is about 120dB lower.
A question for you Mark.
Today I turned up a small board sent to me years ago by a friend, meant to take LND150 and LM334 configured as drawing below shows.
Looking at all the images in the LM334 data-sheet I thought he had made a mistake by reversing the terminals 1 and 3 , until seeing the above posted image of the hornet circuit.
I haven't seen the LM334 used this way anywhere else. The pin numbering in the schematic isn't a typo is it? Just checking.
(BTW. In fact the PCB terminates to pads 1 and 3 of an unnamed TO220 footprint. My thought was the board might have been intended to bias another device, though I don't know .)
Thanks
Today I turned up a small board sent to me years ago by a friend, meant to take LND150 and LM334 configured as drawing below shows.
Looking at all the images in the LM334 data-sheet I thought he had made a mistake by reversing the terminals 1 and 3 , until seeing the above posted image of the hornet circuit.
I haven't seen the LM334 used this way anywhere else. The pin numbering in the schematic isn't a typo is it? Just checking.
(BTW. In fact the PCB terminates to pads 1 and 3 of an unnamed TO220 footprint. My thought was the board might have been intended to bias another device, though I don't know .)
Thanks
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I don't know if there is a standardized way to number the pins of a TO-92 package. In the Texas Instruments/National Semiconductor datasheet, they are not numbered.
By the way, with a resistance ratio of 47, you don't cancel out the positive temperature coefficient, you just reduce it a bit - which is fine if that was the intention.
By the way, with a resistance ratio of 47, you don't cancel out the positive temperature coefficient, you just reduce it a bit - which is fine if that was the intention.
Thanks Marcel, that was what I needed to make me look again. Typically the pins are numbered 1,2,3, left to right when looking at the flat face of a TO-92 /pins down. I looked at the data sheet footprint outline thinking it was a top view but it was bottom. My mistake.
Thanks for the pointer to resistor values as well. I've only just rediscovered a couple of these boards in a drawer - already populated as they were sent - and don't know anything about them. My assumption was that they were low current CCS with some special attribute but hadn't figured out what that was supposed to be. The LND150 suggests high voltage circuit ability but other than that I know nothing.
Thanks for the pointer to resistor values as well. I've only just rediscovered a couple of these boards in a drawer - already populated as they were sent - and don't know anything about them. My assumption was that they were low current CCS with some special attribute but hadn't figured out what that was supposed to be. The LND150 suggests high voltage circuit ability but other than that I know nothing.