Vibracaster - or "How to turn your Valvecaster into a Tremolo"

[biggy boy]

Hi
I took the trannies out and reinstalled them properly.
But it still doesn't work, nothing
So I desoldered the trannies out again and tested them with my meter.
They both measured out at 486Hfe so they both work.
So I guess I'll solder them back in and then check the voltages with the pots removed.

Rick
How critical is the 3.3m value?
the supplier did not have 3.3m so I got 2.7m and 3.9m The board has the 3.9m on it!

Here is the schematic I made using Eagle for the board.
I don't see anything out of place!?!?!?!?!?!

[biggy boy]

That looks like a great piece of work solderman! One thing that occurs to me is that the circuit might operate differently with 24 volts to the plate and 12 volts to the oscillator, I'm not sure but I think the tremolo might not be as strong - I highly recommend you breadboard it before implementing it. The other alternative is the give the oscillator the same voltage as the plate -
Rick

Oh no I just read this
I'm running my tube plate voltage at 157 volts maybe that's why I get no oscillation. The oscillation section is fed with 12volts
I made an add on board for the osillation section and then tied it into my already made valvecaster. The valvecaster runs great at the 157 volt plate voltage.

[frequencycentral]

Rick
How critical is the 3.3m value?
the supplier did not have 3.3m so I got 2.7m and 3.9m The board has the 3.9m on it!

The PSO is a juggling act between values. If you change one you will need to change others to compensate. Have you got a 680K you could put in series with the 2M7 to get 3M3.8? Or you could parallel a 2M7 with a 3M9 to get 1M6, do do this twice, put you two 1M6 in parallel and you have 3M4.

Your schematic looks fine.

One thing that occurs to me is that the circuit might operate differently with 24 volts to the plate and 12 volts to the oscillator, I'm not sure but I think the tremolo might not be as strong

This is a guess - I may be wrong on this.

I'm running my tube plate voltage at 157 volts maybe that's why I get no oscillation. The oscillation section is fed with 12volts
I made an add on board for the osillation section and then tied it into my already made valvecaster. The valvecaster runs great at the 157 volt plate voltage.

You need to assure yourself the oscillator is working correctly first, you should be able to hook up a LED to the output as a visual check that it's running. This is mentioned earlier in the thread somewhere. Once you know the oscillator is working you can apply it to your circuit. If the tremolo is weak you may need to consider lowering the plate voltage.

[biggy boy]

  Have you got a 680K you could put in series with the 2M7 to get 3M3.8? 
Your schematic looks fine.

 

OK thanks Rick

I'll go the 680k way, or go with a trim pot maybe.
Yes its time to isolate just the isolation board and find out whats going on.

[biggy boy]

OK found some 3.3m in the 1/2 watt section of the supplier.
Also picked up a pair of BC549C transistors, they seem to be the same hfe as the 547c, just have a lower max voltage of 45 volts instead of 60 volts.
My pcb is getting battered from soldering and unsoldering parts so may times my need to remake the board
Also going to add sockets to the board to allow the swapping out of tranistors if they don't work.
I have ten of the 457C coming from ebay soon, but will try the 459C in the meen time.
one day I'm get my act together.

data sheet for the 549C
http://pdf1.alldatasheet.com/datasheet-pdf/view/16103/PHILIPS/BC549C.html

Glen

[biggy boy]

OK I got to walk away from this project for a day or two. At age 46 I can't afford to loose any more hair   
I put in the 3.3meg resistor put in the new 549C transistors disconnected it from the tube and installed an
LED now what I have is a fabulous dimmer control for the LED!!!
Still no oscillation.

The speed pot does nothing to the LED. But the second pot the depth one makes it dim and turn off.
At one end it makes the LED very bright as I move the pot towards the other end it goes off and once its at the other end it comes back on but very dim.
I rechecked all the other resistors to make sure the values were correct and they are.

Glen

[frequencycentral]

Hi Glen, sorry you're having trouble getting it going, Here's some info that should help your debug from page 6 of this thread:

OK. Pretty hard to get voltages from an oscillating oscillator!

This first set were taken with the PSO oscillating, but with the depth control removed. I still have the original PSO in a little corner of my breadboard right now. The blank values are because they are changing as the PSO oscillates.

Q1

E: 0.032
B:
C:

Q2

E:
B:
C:11.92


This second set of voltages were taken with the depth pot removed and the speed pot removed to stop the oscillating. Probably more meaningful.

Q1

E: 0.032
B: 0.657
C: 5.54

Q2

E: 4.96
B: 5.53
C: 11.92

I hope this helps. I suggest you remove the speed and depth pots and check the voltages against mine, just work with the PSO part of the circuit, thats where your problem is.

You can get a visual check on oscillation by inserting a red LED between Q2's collector and +ve. It will flash a little weakly though. You should remove it before you complete your build, as it will cause ticking otherwise.

[biggy boy]

Here's the numbers!

The applied voltage 12.20v

Both pots disconnected

Q1

E: 0V
B: .6V
C: 6.77V

Q2

E: 6.18V
B: 6.77V
C: 12.2

I put my LED that I was talking about on the end of the wire that goes to pin 8 of the tube.
I disconnected it from the tube before connecting the LED. The other end of the LED I put to 12v+
I just saw that I was supposed to connect it to the collector of Q2 not the output to the tube?

EDIT:
I just tried hooking a red LED minus side to the Q2 collector and the plus side to 12+ the led didn't do any thing .
I also hooked it up to the output wire that goes to pin 8 and it barely lights, but if I use a green led it light real bright. the green one is the one i use din my other post, not a red one. The green one doesn't work when connected to the collector.
Question am I supposed to disconnect the collector pin from the circuit before hooking the LED to it?



Glen

[biggy boy]

I just can't leave this thing alone LOL

OK more info
I have the oscillation board isolated, no tubes! but hooked up to the pots

12.20 volts Dc applied to the oscillator.
I measure from ground of the board to the out put that goes to pin 8 it measures minus 44 volts?  what? OK
I guess it's minus because the Q2 inverts it, but is the circuit supposed to be a doubler too?
If I measure from gnd to the base of Q2 I get a fluctuating voltage, also from the emitter to gnd the voltage fluctuates.
I take it this thing is oscillating then!?!?

I'm going to try hooking it back up to the tubes and give it a try


Glen

[frequencycentral]

I measure from ground of the board to the out put that goes to pin 8 it measures minus 44 volts?  what? OK
I guess it's minus because the Q2 inverts it, but is the circuit supposed to be a doubler too?

Q2 should just buffer the oscillator, no doubling, how can you have 44 volts there? You are running 45 volts into the tube right? The anode resistor should reduce this considerably though. Are you sure you didn't have your DMM the wrong way around?

If I measure from gnd to the base of Q2 I get a fluctuating voltage, also from the emitter to gnd the voltage fluctuates.
I take it this thing is oscillating then!?!?

That looks like oscillation to me!

[biggy boy]

No I didn't have it connected to the tube circuit at all totally isolated.
LOL Retested the voltage out to pin 8 to gnd and was getting minus 44 volts but I was pinching the test lead between my thumb and finger and the wire coming off of the board that is to go to pin 8 I'm an Electrician by trade I guess all the years of being shocked by high voltage has given me super powers Like a capacitor
If I just put the test lead on the wire that is to go to pin8 I get like 7.6 volts with a very small fluctuation in voltage.

I hooked it back up to the valve caster and still no trem sound.

Rick the LED test I hook the minus side of the LED to the collector of Q2 then the positive to the plus 12volt supply? But do I have to disconnect the collector from plus 12 first?
You know put the LED in series withe the collector?

Glen

[biggy boy]

I bread boarded a new setup.
I used an nte199 supposed to be the same as the bc547C for Q1 and a BC547B as Q2
I did not use pots instead I used 47K resistors in there place to simulate centering the pots.
Did not oscillate.
tried bigger and smaller resistors along with the 3.3m but nothing.
Even tried an NPN with an Hfe of over 1000 for Q1 nope!

I don't know I have 10 BC547C coming in the mail.
I guess I'll go plug my guitar into the ValveCaster crank it up and go have fun until the new trannies come in

Glen

[frequencycentral]

Rick the LED test I hook the minus side of the LED to the collector of Q2 then the positive to the plus 12volt supply? But do I have to disconnect the collector from plus 12 first?
You know put the LED in series withe the collector?

Yes, put the LED between Q2's collector and +ve. I hope you get this sorted soon! It must be frustrating the hell out of you!

[solderman]

I bread boarded a new setup.
I used an nte199 supposed to be the same as the bc547C for Q1 and a BC547B as Q2
I did not use pots instead I used 47K resistors in there place to simulate centering the pots.
Did not oscillate.
tried bigger and smaller resistors along with the 3.3m but nothing.
Even tried an NPN with an Hfe of over 1000 for Q1 nope!

I don't know I have 10 BC547C coming in the mail.
I guess I'll go plug my guitar into the ValveCaster crank it up and go have fun until the new trannies come in

Glen

Hi Glen

I manage to screw up my LFO part of the layout for the wibra caster as well and thougt it was the trannies but it was me as moste of the time. No, I did not get the tremolo part to fire up. I thaught it was because off the to low gain BC547B transistors that I have used.  But I couldn't just sitting there doing nothing just because all the shops were closed and I have to wait until tomorrow so I poked around and used what I hade in stock and this is the result. It's a trem section much alike the original but a bit simpler and with a rate LED. It's a mix of EA tremolo LFO section and this one.

Here is the Schematics (R3 is 15K and i also used BC547B witch i found a bit smother but that could be juat me)


And a crapy sound sample 
http://solderman.fatabur.se/Future%20project/Vibracaster.mp3

//Solderamn

[biggy boy]

Solderman!

Thanks I'll give it a try tonight.
The wire that is marked go to 1N4148 I guess the other end of the diode goes to pin #8 of the tube?? as in Ricks diagram?


Glen

[biggy boy]

OK tried soldermans circuit still doesn't oscillate just turns on the LED?
In the diagram that I attached in the circle is that a junction ( are those wire all connected at that spot?)

Also I don't have any RED LEDs I'm using blue and have tried green, does this matter??

Does this circiut need a load on the wire going to the diode mine is not connected to anything other then 12volts DC

More then six hours and still can't flash a fricking LED with a Transister WTF am I a retard or what?




Glen

[solderman]

OK tried soldermans circuit still doesn't oscillate just turns on the LED?
Check the Transistor is it correctly oriented??

In the diagram that I attached in the circle is that a junction ( are those wire all connected at that spot?)
Yes they are


Also I don't have any RED LEDs I'm using blue and have tried green, does this matter??
NO
Does this circiut need a load on the wire going to the diode mine is not connected to anything other then 12volts DC
Does not matter it runs on both 9 and 12V

More then six hours and still can't flash a fricking LED with a Transister WTF am I a retard or what?

Check my layout for this LFO on page 8 I think Its verified and OK eaven if its PCB you can use it for Vero or Perf. But I think the easiest is to do a dead bug

//Solderman




Glen

[TotemTek]

hu guys!

i built this circuit today. i built it exactly the same as rick's version 3 design on page 6, with all the same component values and everything.

the only thing i don't quite understand is how to power it. do i put all of the V+ points of the circuit to a single 12v dc source? my bypass is working but when i engage the pedal i get nothing! 

i'm guessing it's a simple fix, either a bad joint, incorrect V+ wiring or the wrong kind of capacitor used. I will look into incorrect capacitor type once i've ruled out the previous two speculations.

thanks

[frequencycentral]

hu guys!

i built this circuit today. i built it exactly the same as rick's version 3 design on page 6, with all the same component values and everything.

the only thing i don't quite understand is how to power it. do i put all of the V+ points of the circuit to a single 12v dc source? my bypass is working but when i engage the pedal i get nothing! 

i'm guessing it's a simple fix, either a bad joint, incorrect V+ wiring or the wrong kind of capacitor used. I will look into incorrect capacitor type once i've ruled out the previous two speculations.

thanks

Yup, all the V+ points are connected together to the 12v dc source. Good luck with the debug, you can post your voltages and compare with completed units.

[TotemTek]

my 0.47uF capacitors are polarised tantalum bead capacitors. have i made a bad?