EH PULSAR TREMOLO PROBLEMS...

[tommy_ashclay]

Hi,
I'm Tommy and I'm Italian...
I'm writing to you cause I've got a problem with the Electro Harmonix Pulsar Tremolo...
I've just finished to build it (following the toneamp.com schematic) and the effects sound good...
My problem is that turning the speed pot I can't hear any difference in speed... the tremolo effects has more or less the same speed for any pot position...
Another problem is that I can hear the tremolo effect only using the 0.022uf condenser, while switching on the 0.22uf one the effects sounds like bypassed...
Can it be a transistors problem? I've used bc239 instead of 2n5088... maybe the oscillator doesn't work properly and its waveform isn't big enought to pass the 0.22uf so the Q1 Mos keeps off (that means no tremolo effect) and speed problem could depend on the same matters...
What do you think about it? Any advices?
                                         Thank U, and sorry for my bad english... :wink:

[bioroids]

There are a few errors in the schematic of the pulsar tremolo at Tonepad. One of them is a missing conection on the speed pot. Maybe thats the cause of your speed problems. Althought if you followed the layout (wich is correct) then must be another thing.

I dont know about the transistors you used, be sure to check the pin out. Also on the schematic they are placed wrong, the emitters go to ground, not the collectors. I have a corrected schematic if you want it.

Maybe you have a bad connection/solder somewhere, be sure to check that too.

When you're finished, be sure to place a buffer in front of the effect, as it's impedance is too low to be used as is (in my opinion at least).

Good luck

Miguel

[tommy_ashclay]

Ueh,
 Thanks for your reply!!!
Do you mind sending me (crazytom@axia.it) an email with the correct schematic... maybe the problem is really in the mosfet position...
                                                      see you soon,
                                                               and thanks again,
                                                                              Tommy

[bioroids]

I'll send you the schematic when I get home.

But what Mosfet are you talking about? In my recall, the three transistors on the Pulsar tremolo are NPN 2N5088 (I used 2N3904), there are no Mosfets there, maybe you got a confusion with the EA Tremolo which uses a fet for modulating?

The BC239 should be fine I think, be sure they are placed right because they have different pinout than 2N5088.
BC239 is CBE looking at the letters with the legs down, and 2N5088 is EBC in the same position.

Regards

Miguel

[tommy_ashclay]

Hey,
  I just made confusion... I mean BJT, not Mosfet...
You're right, BC329 (like 2n5088) are Bipolar Transistor, not Mos...   :roll:

However, I've placed the BC like they were 2n5088 without changing the pinout... so I think I find out the problem...
                                  I'll wait for your scheme...
                                                         Thank U,
                                                                   Tommy

[Gringo]

Talk about luck....

Just yesterday i finished populating the board for the tonepad pulsar project :evil:

Could you please send the corrected schem to me too ??
(gringo@worldconquer.cjb.net)

Desde ya muchisimas gracias

[bioroids]

No problem, check your mailbox.

The schem is a little different as it has a buffer and a different switching scheme, but the tremolo part is the same, with the few errors corrected and minor improvements on some values (I think at least)

Let me know if I made some mistake

Regards

Miguel

[mattburnside]

Is the schem the same one that used to be on StonedTone? If not, send it along to me as well. I'm revising the Tonepad PDF to correct the schematic errors, and there's a new layout also.

[tommy_ashclay]

Ueh,
   thank to you I solved my problems and I managed to build the Pulsar... It sounds great, the only problem is the speed pot : too logaritmic...
                         See you,
                                  and thank U again,
                                                        Tommy

[bioroids]

I'm glad it worked  You should use a logaritmic pot for the speed control.

Matt, this is the schematic at Tonepad, it has a few errors. I made a corrected and "expanded" version, wich I can send to you no problem.

Thanks all, goodbye

Miguel

[tommy_ashclay]

Hey,
  Do you mean linear pot? I use a logaritmic one and on 180° last 10° works...
            Thank for you time

[tommy_ashclay]

Hey,
  Do you mean linear pot? I use a logaritmic one and on 180° last 10° works...
            Thank for you time

[bioroids]

I'm using a logA taper pot and works fine, maybe you got a different logaritmic scale? I'm not sure about the posibility of that, maybe someone better informed can explain it to us?

Luck

Miguel

[mattburnside]

Miguel: what I meant was, what did you base your corrections on? If it's the scanned EH schematic that used to be on Stoned Tone, that's the one I based the Tonepad schematic on. I introduced the errors all on my own.  :shock:

Send me your version, if you'd be so kind--my "big" mailbox is
mattburnside@sbcglobal.net

As far as the pot issue goes, I've noticed that too. A reverse log pot might work better.

[difedetry]

Miguel
could you send me a copy of your scheme too?
I've made this great effect and working right to my ears.
I can hear a slight pulsing sound when no playing... but
I think that's normal

gracias!  

» Diego

[difedetry]

I forgot to put my email   :!:

difedetry@hotmail.com

sorry for that  :oops:

» Diego

[Gringo]

Tommy, i think you should try reversing the rate pot, i mean desolder the outer lugs and resolder them inverted, i had the same problem with the rate pot and it was as simple as that. Now the sweep is much more gradual.