Pulsar tremolo modification

[loki]

Hi everybody, i'm trying to build the E-H pulsar tremolo, as from the Tonepad website schematic.
i have a question, would it be possible to add an additional led that pulses in synch with the tremolo time? where should i connect it? is it a difficult mod ?(i'm pretty much a beginner)
thanks! bye

[Mark Hammer]

I'm going to guess here and suggest that the place to insert a "rate" LED is at the junction of R12 and R13 (using the Tonepad layout).  Use a high brightness (>1500mcd) LED, and run a 2k2 resistor to the LED and the LED to ground.

Somebody is likely going to have something to say about current and interactions with the nearby transistor, but at least this will push your request to the top of the stack.

[loki]

thank you very much mark,
just today i found out that the new pulsar tremolo's led (a reissue of the one the tonepad layout refers) in shut down when the effect is turned off and pulses when it's on... i don't know if anybody has a schematic of the new pulsar

[bioroids]

You can connect it as Mark says and cut the connection to ground with the switch. It may work, but I havent tested it.

Luck

Miguel

[loki]

thanks miguel too
i'll try to do it, hope it'll work

[puretube]

the new pulsar tremolo's led (a reissue of the one the tonepad layout refers)...  i don't know if anybody has a schematic of the new pulsar

puretube wrote:

Cc. "EH Pulsar": note that the new aka "re-issue" Pulsar has absolutely nothing in common with the vintage one (which appears in some DIY-archives), except the name...

the new Pulsar`s schem is not supposed to appear in public, sorry.

[loki]

I've finally built it!!! it was my first build and i'm very proud of it
the perfboard came out perfect, i didn't mistake anything... i did some mess instead with the 3dpt switch and jack plugs connections.... but then i started all over and it finally worked!
the fx is just perfect, no noise at all, no pops, no background pulsation when it's bypassed...(i haven't boxed it yet) very good! the only thing is that the rate pot is a bit harsh, most of the speed variation is concentrated in the last 2 degrees of the pot rotation. i tried to use a linear pot instead of the listed log one, but no variation.... i've heard many people reporting this, so i guess it's just the pedal that works so and you can't help it
unfortunaltely i wasn't able to put the rate LED, i've followed the suggestions mark gave me here, but it doesn't work... but anyway the pedal is great!
maybe i can post some pics as soon as  i box it
bye!

[bioroids]

You should try a reverse-log pot, or else use a log pot but wired so that turning it clockwise gives the slowest speed. I did that and got a better use of the pot.
Maybe you could connect the pulsing led using a simple npn buffer:

conect another 220k resistor to the place R13 and R12 join (the same place where the middle lug of the soft/hard switch goes), that resistor to the base of a npn (say 2n3904), the emiter to ground, the collector to a 5k6 resistor, and then the led from the resistor to +9v.

I think that should work (never tried), maybe you have to mess with the resistor to the base (lowering) to get enough current to turn the transistor on, but if its too low it may affect the lfo. Experiment, the 5k6 resistor is for limiting the current into the led, may work from 1k2 to 10k maybe.

Let us know if you try it and how it works.

Good luck!

Miguel

[loki]

thanks for the tips miguel
i'll try to do it and let you know

[R.G.]

the new Pulsar`s schem is not supposed to appear in public, sorry.

I know the problem - my schematics are always running around, being rowdy, and appearing in public, completely uncovered. Doggone pesky, misbehaving things. Tsk, tsk.