sin-wave transistor based wien bridge oscillator

[teusz]

wien bridge oscillator using transistor

Hi,

I need to build sin wave generator. I have schematics (below in attachment), I cannot change anything. Maybe except thermistor which I should replace by bulb.

What I want to ask is want values of elements should I use. Maybe you can write some values with which this generator should work? I would be some start for me.

Thanks in advance

 

[FvM]

design sin oscillator

Only one hint. An thermistor (NTC) can't be replaced by a bulb (PTC) without exchanging R3 and R4. Furthermore, the NTC (or PTC) is a critical component, it basically determines the impedance level of the circuit. Finally, the intended frequency and supply voltage should be known.

 

[teusz]

sin oscillator+transistor

This hint is unfortunatly not enough for me. Actually for us.
We're trying to figure it out with friends and still don't know how to determine proper values of all components. We was trying to simulate this circuit in PSpice and still we don't have output signal is far from sin wave.

 

[FvM]

wien bridge transistor circuit

R=10k
C=10n
R3=205
R4=100
R5=4M7
RC1=2K2
R6=47K
R7=10K
RC2=200
RE=50
C1=1u
C2=1u
C3=10u
CE=100u
Ucc=15
T1=T2=BC547C

=> f = 1.6 kHz
u = 2.8 Vrms
THD= 1.8%

Simulated with fixed R3/R4 and minimum gain reserve, so oscillation startup takes
about 100 ms. Simulation behaviour may be different depending on simulator and simulation options.

 

[teusz]

transistor based wien bridge

thanks a lot!