EH Pulsar schematic error?

[spoontex]

Hello,

My first pedal that I build a few years ago, was the EH Pulsar. But, everybody knows that this pedal have some issues.

The first one is the famous tick, when the pedal is bypassed. I solved this issue putting a buffer in front of it ( Boss pedal ), and the tick disappear.  So, I redraw the schematic and add a buffer in front of the effect, taking advantage of the dual opamp tl062. But this way didn't work. I don't know way.

Anybody can help it the buffer?

And the second issue, is that when the pedal is on. It isn't very clean... tick again ( like a heartbreath ).

Trying differents transistors, unintentionally reversed the Q1 transistor... and suddenly the heartbeat is more more attenuated. I'm not an electronics expert. Someone can explain this?

Thanks.

P.D.: I know, they are other tremolo pedals... but this is my first build when I was young... jaja

https://i.ibb.co/cb8R1X5/pulsa2.png

[j_flanders]

Re: EH Pulsar schematic error?

This is the schematic I have.
The differences I see are:
* R2 is 47k instead of 27k
* Depth pot is 100k instead of 1M
* Some caps are specifically stated to be tantalium.
* different transistors, 2N5088 (one 2N5089?) instead 2N3904

The first one is the famous tick, when the pedal is bypassed. I solved this issue putting a buffer in front of it ( Boss pedal ), and the tick disappear.  So, I redraw the schematic and add a buffer in front of the effect, taking advantage of the dual opamp tl062. But this way didn't work. I don't know way.

Anybody can help it the buffer?

With the Boss buffer/pedal before the Pulsar, when you bypass the Pulsar, the Boss buffer is still on.
With the buffer inside the Pulsar, when you bypass the Pulsar, you also bypass the buffer.

My theory is that the ticking only happens when there's an unbuffered signal running through the wires inside the Pulsar (from input jack to switch to output jack when in bypass).

My big box Pulsar ticks more or less depending on how far those wires are apart from the jacks and pcb inside the pedal. And also how far the jacks are away from the pcb.
Once I put shielding between the pcb and the jacks it went away completely.

I explained it more extensively over here:
https://www.ehx.com/forums/viewthread/9710/

[duck_arse]

looking at the ehx original dia shows three ground connections for the oscillator section. note that they are drawn all coming to a single point. keep that point seperate from the audio grounds, "the other side" of the ground wire to the pcb, if possible.

this just in - also note the four oscillator connections to +9V is shown to one point only.

also note the ehx doesn't bypass anything, it only shorts the shunting transistor, doesn't even stop the osc.

running the oscillator supply from before an R//C filter to the audio section might help. also, if you're desperate, you might try adding a small value resistance between the 200k and 470nF and the 470nF and 2M2 - it might add a little drag to the transients.

[spoontex]

The different values are typo error.

I will try the shield. But, why the effect is clearer if I flip Q1??

thanks.

[PRR]

> reversed the Q1 transistor... and suddenly the heartbeat is more more attenuated.

A BJT will work "backward", at reduced C-E breakdown voltage, and lower current gain. Since this plan does not put a heap of current into Q1 base, with lower gain may come less effect.

[spoontex]

Thanks PRR,

I shielded everything. Out, In, FXin, Fxout. And yes... more much better!!

Thanks for all.