Whats wrong with this oscillator circuit?

Status
Not open for further replies.

angy

Full Member level 3
Joined
Jul 9, 2008
Messages
151
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Visit site
Activity points
2,341
I am not able to generate f= 1.6Khz .Kindly let me know whether circuit is alright .Output can be taken on VF1 also

 

Angy, exchange R5 and R4 in order to get a gain of 3.
At the same time - to ensure a safe start - make R5 a bit larger (20.5 kohm).
The diodes remain where they are (across 20.5 k)

Sorry - I was confused. My above comment does not apply. I had overlooked R1.
However, R4 seems to be too large. Reduce it to 1...2 kohms.
More than that, for simulation purposes (to start oscillations) you should
* either switch-on one or both power supplies at t=0 in transient simulation
* or give one of the capacitors an intial condition (IC with some millivolts)
 
Last edited:


I tried still not working
initial voltage given to capacitor set to 500mV, also changed R4 to 1K
 

I tried the circuit with the schematic you post and it works without any modification. The oscillations have a frequency of about 1350 Hz and amplitude roughly 1.6 Vpp.

As said by LvW, unless you set the initial conditions of the capacitors, you cannot use battery to supply the circuit (for simulation purpose) but you need to use for instance a pulse generator that switch from 0 to Vcc at a defined time instant (for example 0). I used a pulse generator from 0-->12V at t=1us, rise time=fall time=1 u, pulse width=1 s, pulse period=2 s (optionally you can do the same for the -12V supply).
The problem with the battery is that the simulator assume the voltage is there from -infinity then all the reactive parts (capacitors and inductors) are considered fully charged.
 

Yes - I agree to albbg,

one additional hint for angy:
Did you utilize a sufficient time resolution - for example a max. step size of 1µsec? (should be at least 1/100 of the period).
 

Status
Not open for further replies.

Similar threads

Cookies are required to use this site. You must accept them to continue using the site. Learn more…