Throb tremolo problem

Started by Tombaxter97, November 17, 2017, 05:41:57 PM

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Tombaxter97

Hi guys,

been trying to get this circuit working for a while now. (On breadboard)

Q1: C - 0v
      B - 0.52v
      E - 0V

Q2: C - 9.07v
      B - 8.67v
      E - 8.63V

Q3: C - 9.07v
      B - 1.18v
      E - 0.63V

Q4: C - 1.23v
      B - 0.63v
      E - 0V

http://pedalparts.co.uk/docs/Throb-V4.pdf

I originally had the flashing LED layout and a 3 way switch for the fast and slow and when there was power the led would flash once and stay off and I would get no output signal. I removed the LED and R17 and also the switch section - just connecting C8 and R13 straight to R15 - for simplicity until I have it working. I'm guessing the problem is at the oscillator side of the circuit but I have no voltage drop over R5 and R6 and a collection at Vcc, this does not seem right to my understanding but I am probably wrong.

Any help or pointers would be appreciated very much!

Thanks

Kipper4

Q2 looks like it's open circuit. Solder bridge?

Q4 could be R8 is not connected.
Either way the collector should be nearer +9v.
Ma throats as dry as an overcooked kipper.


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/

Tombaxter97

R8 is in the circuit but I suspect it is something around there, I'll keep checking!

duck_arse

like kipper says - power off, and measure the resistances around Q2. collector to R6//C2, emitter to ground, base to collector. and measure from the transistor pins.

and, of course, we'd like to see pictures.
don't make me draw another line.

Tombaxter97

Its on breadboard so will pictures help much? i'll try that now

duck_arse

we'll look at anything around here.
don't make me draw another line.

Tombaxter97

Hahah okay, well after fiddling about with Q2 collector and the resistors the voltages are now

Q2. C - 2.68
      B -  2.14
      E - 8.63

Will probe about and update, thanks for the help.

duck_arse

mmmm, you'd be wanting the collector higher than the emitter. what transistors are you using?
don't make me draw another line.

Tombaxter97

thought that was weird. 4 2n5089's

Kipper4

Is the transistor in backward or something cause as Duck says the collector of q2 should be near to what your emitters voltage.
Ma throats as dry as an overcooked kipper.


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/