EHX - Rolling Thunder Schematic Redraw (Percussion Effect)

[Scruffie]

Been looking for this Schematic for a Long Time, Mr.Giles managed to help and provide me with a copy though so here's the Redraw of it!

Not Fully Checked but Good at a Glance, Notes at the Top Left I think are all Good.

Enjoy! 

[StereoKills]

Interesting, I wasn't able to find much information at all after a quick google search. What role does the crystal mic play?

[Scruffie]

Interesting, I wasn't able to find much information at all after a quick google search. What role does the crystal mic play?

It's not really a stompbox as such, it's a small electronic drum in a Big Muff enclosure, so you hit the mic and it produces a Thunderous Sound.

Information - http://electroharmonix.vintageusaguitars.com/index.php?option=com_content&view=article&id=22:the-different-drummer-pt-2&catid=13:electro-harmonix-articles&Itemid=45

[StereoKills]

Gotcha! That looks like it would be interesting to play around with!

[Frances Rhodes]

hey!

been looking for this schematic for quite a while now, good to know i wasn't the only one!!
one question, was this supposed to be a "bass drum" (very low) sound or a "tom/bongo" (rather medium) sound? i'm confused with the sonic boomer...

and is U2 an OTA?

cheers

[Scruffie]

hey!

been looking for this schematic for quite a while now, good to know i wasn't the only one!!
one question, was this supposed to be a "bass drum" (very low) sound or a "tom/bongo" (rather medium) sound? i'm confused with the sonic boomer...

and is U2 an OTA?

cheers

Check youtube, pretty sure I saw a demo of it some time ago. But I think it's very low.

As the top corner states, probably a CA3094 (can't confirm this) which yes is an OTA, probably better off trying to rework it for half a 13700 than finding or paying for that chip. Or at the very least the CA3080 + Darlington buffer combo.

[Frances Rhodes]

ok, i'll check youtube for soundclips!

about the OTA... i'm afraid i'm not good enough in electronics to be able to try such substitution (OTA + darlington buffer). there are far too many things i still don't know/understand in electronics... if i decide to build one, i'll maybe try a 13700 and see how it sounds and if it need any further adjustments, i'll leave it to people who know what they are doing!!

thanks for the heads up by the way!

[Scruffie]

ok, i'll check youtube for soundclips!

about the OTA... i'm afraid i'm not good enough in electronics to be able to try such substitution (OTA + darlington buffer). there are far too many things i still don't know/understand in electronics... if i decide to build one, i'll maybe try a 13700 and see how it sounds and if it need any further adjustments, i'll leave it to people who know what they are doing!!

thanks for the heads up by the way!

There's no guarantee a 13700 will even work even though they're simmilar chips.

Also there's no guarantee that the factory schematic I worked from was even right, they regularly had ones with mistakes thrown in to throw off cloners.

Really someone needs to either breadboard it with the original chip before attempting a conversion or provide gut shots so it can be traced through and confirmed.

The CA3080 + Darlington buffer set up can be observed in the tone pad small stone schematic. I think there's a schematic for a CA3094 too, i.e. using transistors to replicate the internal circuitry.

[StephenGiles]

U2 is defininitely CA3094 because output is from pin 6. If output was from pin1 then a CA3080 could probably be substituted, but in this case you need to consider why EH felt the need for the darlington output - gotta be a reason!