Click in any of below diagrams to simulate circuit. The online calculators all deliver DC quiescent state, but none include AC small-signal estimations.
C1 – Basic gain stage
C3 – Fixed-bias
cathode follower
cathode follower
C2 – Self-bias cathodyne
phase inverter
(also cathode follower)
phase inverter
(also cathode follower)
C5 – Fixed-bias cathodyne
phase inverter
phase inverter
C4 – Gain stage
+DC-coupled cathode follower
+DC-coupled cathode follower
C6 – Cascode
C8 – Cascode SRPP
C7 – Phase inverter
fixed or cathode bias
fixed or cathode bias
C11 – Dual-triode mixer
C12 – Dual-triode mixer
with dissimilar cathode circuits
with dissimilar cathode circuits
Circuits available only in PC app
From version 1.9, most calculators deliver small-signal estimations of gain and impedances.
C9 – Dual stage amplifier with level shifting
C10 – Phase inverter: constant-current bias
C13 – Gain stage, constant current bias 
C14 – Gain stages with DC level shifting 
C15 – Differential phase inverter, long-tail pair, cathode bias 
C16 – Serial voltage regulator 
C17 – Basic serial voltage regulator 
C18 – Shunt voltage regulator 
C19 – 3-stage coupled by HV line 
C20 – 2-stage coupled by HV line 
C21 – “Aikido” cascode (Tubecad)
C22 – Cascode for preamp (Tubecad)
C23 – PP amplifier DC feedback (Tubecad) 
C24 – SRPP headphone amplifier (Tubecad) 
C25 – Basic current source 
C26 – CCDA Constant Current Draw Amplifier line amplifier (Tubecad) 
C27 – Janus cascode Shunt regulator (Tubecad) 
C28 – Totem pole split load phase splitter (Tubecad) 
C29 – Triode with anode to grid feedback 
C30 – Mu-follower 
C31 – Cascode SRPP+ 
C32 – Common-grid gain stage
C33 – White cathode follower 
C34 – Half-mu stage 
C35 – Cathode follower with current sink 
C36 – Pentode amplifier 
C37 – SE triode power 
C38 – SE pentode power 