In Reply to: RE: Feedback, no feedback and selective feedback posted by Lew on October 10, 2010 at 15:08:35:
'Mutatis mutandis' I think this selective feedback network can be applied to the majority of commercial circlotrons.
The selective feedback network is made of R13, R22, R21, R20 and C5.
The feedback signal is picked across the normal speaker output (paying much attention to the polarity to prevent wild oscillation).
In this example there is room for about 11 dB feedback at low/mid frequency, 7.5 dB at 10 KHz, 3 dB at 20 KHz and zero feedback above 30 KHz.
Changing the value of C5 will allow to increase or decrease the 10-20KHz feedback.
Changing the value of R13 and R20 allows to trade in more low frequency feedback (i.e. lower output impedance) in exchange for reduced mid-band gain.
Best Regards
Luca
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Follow Ups
- A possible selective feedback for circlotron - 6AS7_6SN7 01:49:57 10/12/10 (13)
- RE: A tricky issue - Ralph 10:25:11 10/12/10 (10)
- RE: A tricky issue - Lew 22:48:33 10/12/10 (9)
- It is not a tricky issue at all - 6AS7_6SN7 01:14:20 10/13/10 (8)
- RE: It is not a tricky issue at all - Lew 07:03:14 10/13/10 (7)
- You are absolutely right! - 6AS7_6SN7 00:44:26 10/14/10 (6)
- RE: You are absolutely right! - Ralph 11:05:49 10/20/10 (3)
- RE: You are absolutely right! - Banat 05:28:04 10/21/10 (1)
- In this particular case I have found that.... - 6AS7_6SN7 11:35:59 11/28/10 (0)
- We made all the points quite clear....... - 6AS7_6SN7 23:56:08 10/20/10 (0)
- RE: You are absolutely right! - Lew 19:51:52 10/14/10 (0)
- RE: You are absolutely right! - Banat 10:10:48 10/14/10 (0)
- RE: A possible selective feedback for circlotron - Banat 09:03:49 10/12/10 (1)
- I know there is always room for improvement... - 6AS7_6SN7 09:38:21 10/12/10 (0)