JFET-only Circlotrons without negative feedback

hi

UJ3N065080K3S model is already in FULL_JFET.txt, but i don't know if it's a good idea to use a mosfet in the diagram

but i donc know how to create a Jfet subckt

yes R6 need to be adjusted but the quiescent current is not a problem.

In simulation the gain is too high, my 2sj103 model should be wrong
 
Last edited:
Hi!
In the next thread there are 2sj103 models (JFET and MOSFET SPICE models). It seems that this is the only 2sj103 model that can be found.

.model 2SJ103Y PJF(beta=1.053m vto=-1.342 is=1n cgd=8.0445p cgs=4.9555p lambda=34.8 mfg=TOSHIBA)
.model 2SJ103GR PJF(beta=2.283m vto=-1.342 is=1n cgd=8.0445p cgs=4.9555p lambda=16 mfg=TOSHIBA)
.model 2SJ103BL PJF(beta=5.092m vto=-1.342 is=1n cgd=8.0445p cgs=4.9555p lambda=7.2 mfg=TOSHIBA)
 
Last edited:
I also found such models:
.MODEL 2SJ103 PJF(BETA=2.197M RS=76.76 RD=76.76 BETATCE=-.5 LAMBDA=735.3U VTO=-2.037 VTOTC=-2.5M CGD=18.95P M=.5045 PB=.3905 FC=.5 CGS=17.02P ISR=38.48F NR=2 IS=3.848F N=1 XTI=3 ALPHA=10U VK=100 KF=1E-18 AF=1)
.MODEL 2SJ103BL PJF (BETA=898.438U IS=10F RD=200 CGD=11.9398P CGS=14.4P)
.MODEL 2SJ103GR PJF (VTO=-1.62622 BETA=16.1875M LAMBDA=1M IS=10F RS=186.826 CGD=13.2918P CGS=14.3694P PB=806.232M KF=0.001F AF=500M)
 
HI

With the difficulty of finding input jfets, I thought why not bipolar, so I tried to simulate this one

Jpatay, this is the amp so I spoke to you in December, but I just invert the schematic and put the Power Jfet that you proposed
 

Attachments

  • Circlotron.audio.ZERO.png
    Circlotron.audio.ZERO.png
    59 KB · Views: 870
HI

With the difficulty of finding input jfets, I thought why not bipolar, so I tried to simulate this one

Jpatay, this is the amp so I spoke to you in December, but I just invert the schematic and put the Power Jfet that you proposed

Hi Seb!:wave:
It is very good that you have completed this circuit. It would be nice to collect and listen to it.
And also check for thermal stability. Spring. I don’t want to do anything.😉
 
Measured its stock SIT-JFET KP802A (КП802А).
A total of 114 pieces, 87-92 production years.
Began to disassemble the "fours".
In the attachment is a table of those with the highest drain current initial, the tip of the iceberg.
Schedule for the "average" of the four transistor 57 / 98 - 36 / 37.
Average parameters calculated: Ri=(15-5)/(1,89-0,747)= 8,7 Ohm, S=(2,27-1,49)/(1,5-0,5)=0,78 A/V, u=RixS=6,8 units.
Output impedance of the common-drain amplifier:
1/S=1,28 Ohm.
It is seen that the output arm voltage should be kept 18-19 V. For these numbers.
 

Attachments

  • КП802А_ ВАХ_ кв.57-98-36-37_.jpg
    КП802А_ ВАХ_ кв.57-98-36-37_.jpg
    570.1 KB · Views: 708
  • КП802_пари_57-98_36-37_повт. в.jpg
    КП802_пари_57-98_36-37_повт. в.jpg
    167.5 KB · Views: 669
Last edited:

Attachments

  • 2128184675567.png
    2128184675567.png
    259.6 KB · Views: 608