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

[frequencycentral]

You can use a number of diode/cap stages to get much higher voltages using the MAX1044, have a look in 'Circuit Sweepings' over at Geofex.

[solderman]

Hi
I have just finished the VibraCaster.

The Drive part works grate but it wont oscillate.

I have built it on this PCB



Q1 (the one surownded by R7 3M3)
E=0
B=0.58
C=7.95

Q
E=11,76
B=7.91
C=7,29

At lug 3 of Depth=3.55 not moving


I have used the BC457B

Anny suggestions

//Solderman

[frequencycentral]

Q1 (the one surownded by R7 3M3)
E=0
B=0.58
C=7.95

Q
E=11,76
B=7.91
C=7,29

This set of voltages were taken with the depth pot removed and the speed pot removed to stop the oscillating. With the oscillator running it's impossible to take volatges, as they are changing all the time!

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. 

Comparing your voltages with mine, it looks like all the Q2 voltages are well off, so thats the palce to start. Is the transistor correctly oriented? You Used BC547B, these are lower gain than BC547C, that might be enough for the oscillator to be too underpowered to start

[solderman]

Hi Again

No, I did not get the tremolo part to fire up. I guess its because off the to low gain BC547B transistors that I have used. But I'm off to by C:s tomorrow so I will find out if that fixes the tremolo part. 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 EH 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)




Here is a sound sample of me abusing a Stratocaster and playing with the depth, speed and gain pot.

http://solderman.fatabur.se/Future%20project/Vibracaster.mp3

Hers a pic of the test rig.



//Solderman     

[DiamondDog]

Good news Diamond Dog!
..
Check it at HIGH volume. Maybe I'm just being precious, but I had to find a fix that prevented it ticking under ANY circumstances.

What? You want me to check it at HIGH volume- through two Blackface modded Twin Reverbs???

OK!   

I'll throw the diode and cap back in when I'm at home again... There's no harm covering as many bases as possible. Like a bulldozer chasing butterflies.

Again- good job! Love your work!

[Renegadrian]

Solderman, I like your last experiment...Did you try it on vero too? 

[DiamondDog]

Good news Diamond Dog!
..
Check it at HIGH volume. Maybe I'm just being precious, but I had to find a fix that prevented it ticking under ANY circumstances.

What? You want me to check it at HIGH volume- through two Blackface modded Twin Reverbs???

OK!   

I'll throw the diode and cap back in when I'm at home again... There's no harm covering as many bases as possible.

Again- good job! Love your work!

[solderman]

Hi

Solderman, I like your last experiment...Did you try it on vero too? 

No, But if you download the DIY file and open it in  DIY layout Creator (the old one)  you will probably be able to fix one in a wink.

OK, being a newbe to tubes means making misstakes. The first I made was to assume the pinout of the tube went clockwise WRONG.  OK, only to redraw and etch a new board.  Then the Trem woldent fire up.  After a lot of tweeking and hassling with it I finlay bought new trannis and I change to BC547C in stead of B. That did nothing.    Then I changed the whole layout for the LFO on the PCB to the one on my schematick. Thath one one did NOT work ether on the PCB even though it worked perfectly on the test board.    After thingking looking and thinking again and looking with my absolutely strongest magnifying galss I found a bit of trace that was not connecting between to caps. it was about .05 mm but enough to fool me. The original LFO would probably have worked if i had spotted this earlier. But now it works and sounds good. here is some of my findings. I have tryed with both BC547B and C in this LFO and both works.

• About the MAX 1044. It has run for 48 hours non stop without complaining or getting warm. I find thath the head room is better at 24V then on 12V but thath was expected.
• I put a 10uF E-lyt parallel L 1-2 of the Depth pot to cancel the motorboating sound.
• I put a 68K in series to L3 on Dept to limit the depth to usable level. You can omit this to get real weird sound
• The LED has to be on at all time. The circut need 0,5-1,5 sec to load the caps through the LED and if switched by a 3DTP yo will lose the term for the first part of your song. I have solved this by potting in a LED two colored LED with common Anode. that gives my a read color when in bypass and a green when ON. A good thing is that you can see the speed of the trem even when it is bypassed. This is what S9 solderpad is for
• Everything works eaven on 9V bot the headroom is lower and the clipping is less nice.

The pics and links I have posted earlear are updated but I post them again just to be sure that no one uses the ones that dos not work.





http://solderman.fatabur.se/Future%20project/VibraCaster.diy


//Solderman

[frequencycentral]

Hey, really glad you got it running solderman, I get a real bad sense of culpability when someone builds one of my designs and it doesn't work first time - even though I have built it from the same schematic a couple of times! I have to get over that - I lost some sleep for you!

Your PCB looks ACE by the way, and I really enjoyed your soundclip - can't wait to see the finished pedal too.

[Renegadrian]

Anders, for what i understood this one is not what you put in the biggest layout? but you tried it and it works, as for the soundclip...So yep I'd like to turn it into a vero layout. Gonna do it in the next days, so I wondered if you did it already...

[solderman]

Anders, for what i understood this one is not what you put in the biggest layout? but you tried it and it works, as for the soundclip...So yep I'd like to turn it into a vero layout. Gonna do it in the next days, so I wondered if you did it already...

Well It actualy is the same LFO circut if you look at the layout and the schematic you can se that.

On the layout C6,7 and 8 are C1,2,3 om the scematic

C4=C9
R1=R8
R2=R7
R3=R5
R4=R6
R5=R9

Cant remember If I updated the DYI file but Ill check thate later.

[kurtlives]

Can someone look over the layout at the TOP of PG 5 please?

I wired the speed and depth pots backwards and it works. Well works in the sense that depth adjusts speed. And the speed control does nothing.

If I switch them around to their proper positions I get no trem effect.

[solderman]

Can someone look over the layout at the TOP of PG 5 please?

I wired the speed and depth pots backwards and it works. Well works in the sense that depth adjusts speed. And the speed control does nothing.

If I switch them around to their proper positions I get no trem effect.

Hi Chris

I have looked over the layout and as far as I can see, everything checks out. A way for you to trouble shoot it would be to replace the 1N4148 with a LED, oriented as the 1N4148 and connect the anode to +12V instead of pin 8. If I have understood the circuit it supposes to lower the potential at lug two on the depth pot to GND in a sine wave. This will mean that the LED will flash when/if everything is OK.

So, do the Ursula's, look for solder bridges etc. As you can see from my post above I spent hours to find a tiny trace cut that I accidentally made drilling a hole to correct a layout error I made in my first layout.

//Solderman

[frequencycentral]

@ kurtlives - I checked your layout too, it looks good to me, so the fault must lie elsewhere - maybe a solder bridge as solderman says, or a wiring error. Stop the oscillator by removing the speed and depth controls then post your voltages for Q1 and Q2.

[solderman]

Hi
I'm proudly introducing Mr U-tube.

Credit to Rick who started this thred about a valve tremolo.
This is my result. Now it is boxed and I'm quit happy whit the result it sounds good to my ears. The wooden line is a washer to make up for the distance needed inside. 30 mm wasn't enough to host the tube socket and the jacks upon each other.






//Solderman

[frequencycentral]

Wow that's a tight fit! No wonder you neded the washer - I love the U tubes! I've got a couple of those nice knobs in black for my mojo FF build. Now - soundclips and gutshots please!

[solderman]

Hi
OK, a gutshot wouldent be anything to se caus its only the backside of the PCB. but here is the content of the box. Everyting is on the PCB exept the jacks that have there one. The yellow and purpel cables are of caus hooked ut to the stompswitch in the box togeter with the LED.



Sound sample
http://solderman.fatabur.se/Future%20project/Vibracaster.mp3

//Solderman

[kurtlives]

Rick I got some voltages with the pots disconnected...

Q1
C - 7.79V
B - 0.63V
E - 0V

Q2
C - 14.23V
B - 7.77V
E - 7.19V

They actually seem quite good dont they? More or less in line...I wanna check Q1's emmiter area though.

Any suggestions?

[frequencycentral]

Rick I got some voltages with the pots disconnected...

Q1
C - 7.79V
B - 0.63V
E - 0V

Q2
C - 14.23V
B - 7.77V
E - 7.19V

They actually seem quite good dont they? More or less in line...I wanna check Q1's emmiter area though.

Any suggestions?

Yes, they look pretty close. Your Q2 collector is 14.23V - is your DC just very slightly above that? My voltages were taken with DC of 11.94 volts.

Frustrating! There is nothing really obvious from your voltages. But yes, Q1's emmiter looks a bit suspect, and I would expect it's base to be higher too.

[kurtlives]

For the time being everything is wired a bit loose and no regulator. That's why I get the 14V.

Very frustrating indeed... My ideas....cold joint, solder bridge, bad pot. I am sure it is on of the three.