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Old 21st November 2008, 08:03 PM   #271
Thomo is offline Thomo  United Kingdom
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Quote:
Originally posted by mikvous
Lee,
Which version are you trying.Don't worry we'll find it

Hi there. It is this one

Regards, Lee.
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Old 21st November 2008, 08:30 PM   #272
Salas is offline Salas  Greece
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Hi, it is possible that your last Q (buffer NJFET) has higher than calculated Idss and drops its Vd too much, Vg under its Vs, so it won't work. Given that all your parts are correctly oriented (most possibly) I would use a smaller resistor on its RC filter (R20) maybe 470R, same for R19, and see if I get sound. Measure the DC on its gate and source please. See that the gate sits slightly higher than the source.
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Old 21st November 2008, 09:00 PM   #273
Salas is offline Salas  Greece
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Quote:
Originally posted by Thomo
Today I finally found time to build this circuit. Unfortunately, I am not getting any sound output.

Being pretty noobish, I have a noobish question if you don't mind. I'd just like to check that I have the FET's and transistor the correct way round. Which pins on Q6 are tied together please? And is it pin 1 of Q3 (bc550) that connects to Q1?

Cheers, Lee.

(Confused as to why it won't work)
As you watch the 2SK170 upright looking at its flat face, the 2 right legs tie together for Q6. From left to right, D G S. As for the BC550 see the attachment.
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Old 21st November 2008, 09:52 PM   #274
Salas is offline Salas  Greece
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Hey Thomo, did you solve it? Vd and Vg higher than Vs?
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Old 21st November 2008, 09:53 PM   #275
Thomo is offline Thomo  United Kingdom
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Hi Salas, thanks for your help. The voltage on Gate of Q5 is oscillating wildly from ~4v - ~12v. Source is ~9v.

I matched these fets using the method shown in an earlier post, and this is making me question the accuracy of my meter.

I will try as you suggested and reduce the value of those two resistors.

Regards, Lee.
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Old 21st November 2008, 09:54 PM   #276
Salas is offline Salas  Greece
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Source is high. See Drain, to be higher than Source.
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Old 21st November 2008, 09:55 PM   #277
Thomo is offline Thomo  United Kingdom
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double post
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Old 21st November 2008, 09:56 PM   #278
Thomo is offline Thomo  United Kingdom
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I re-checked all joints and now get a loud hum and very quiet music. Which is better than before, lol.

All connections are good, so it must still be something else.

Regards, Lee.

edit: Vd is ~14v so yep, higher than source.
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Old 21st November 2008, 09:58 PM   #279
Salas is offline Salas  Greece
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I want you to see Q5 and find S about half the D and G slightly higher than S, for Voltage.
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Old 21st November 2008, 10:01 PM   #280
Thomo is offline Thomo  United Kingdom
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I will have to check into this more tomorrow morning as my wife is pestering me (again). I suppose I have to give in sometimes, lol.

Many thanks for your help so far. Kind regards, Lee.
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