Pulsar Tremolo: Lower Speed??

[Zero]

Hi guys!

I'm currently stuck with the Pulsar Tremolo.. I built it from Tonepad's layout...
It worked right from the start, which is quite unusual in my experience  

The thing I'm unhappy with is the speed control.
First, I think most of the change happens in the last quarter of the pot, and there it goes from 20% to 80% all of a sudden. I'm using  a log pot as proposed in the layout. Has anyone tried with a linear pot?

Second, the minimal speed seems too high to me. I've thought about changing the pot's value or lowering R16, which is 'limiting' the LFO when the pot is at 0... (am I seeing this right?) But as R16 is only 1.1k compared to the pot which is 100k I don't think it would make much of a difference.

Does anyone know of a convenient way to lower the speed?

Greetings from Switzerland

Zero

[bioroids]

Hi!

I use a linear pot for the speed control, but is only marginally better. I think the solution is a reverse log pot... never tried it though.

The limiting resistor is for the max speed, if you remove it the trem will go faster on the max setting.

If you want to lower the speed you can change the 1M resistor on the LFO for 2.2M. It will lower the max speed also. Also you can try changing one or both 0.47uf caps with 1uf.

Luck!

Miguel

[Zero]

Thanks Miguel!

I'll try increasing the 1M resistor then...
I don't have a reverse log pot lying around, but when I get one, I will try it for the speed control.

Muchas gracias por tu ayuda! Un saludo hasta Argentina.

Zero

[RDV]

Wire a log pot backwards and you'll have a reverse log pot, but then you'll have to remember that the max speed is at 0 on the pot and minimum @ 10.

RDV

[bioroids]

Hi!

RDV is right, you can wire the log pot backwards and it works much better, despite the fact you get the lower speed turning it clockwise. I forgot I have tried that!! :roll:

Luck

Miguel

[Gringo]

I did the same thing (using a regular log pot wired backwards) and it did the trick for me

[Zero]

I just completed the Mods..
The pot is now wired backwards and I changed the 2.2M resistor (R17 in tonepad's layout) with 3.3M. I tried 4.7M too, but it was too slow  

Speed control now really is what it should be... And the "sacrifice" of the opposite turning sense is quite small.

Thanks everyone!
Especialmente a los compañeros Argentinos    

Zero

[bioroids]

Hi!

I'm glad it worked fine!

Tell us, did you notice too much clicking or LFO noise bleeding thru the signal? The Pulsar got a reputation of being a little noisy, in particular when you turn the depth control down

Luck

Miguel

[Zero]

Sorry about the delay--

I've noticed noise from the LFO... But it wasn't at a level where it would disturb me. I haven't boxed the effect, I must add. I just connected the PCB to my practice amp.
But with an enclosure, it should only get better   :wink:

Cheers,

Zero