EHX - (Super) Space Drum (Percussion Effect)

Scruffie · Post by **Scruffie** » 16 Nov 2010, 21:33

Another Schematic Redraw, You can build either the Deluxe Super Space Drum or 9V Battery Model with this schematic. Not Fully Checked but Good at a Glance. One resistor at the Top Right I can't read the Value of on the Schematics I have... 2 or 3 something, i'd guess 2k2 or 3k3.

According to an Electro Harmonix Price List Mark Hammer posted, this was apparently used by 'The Clash'

Video Demos!

Scruffie · Post by **Scruffie** » 29 Nov 2010, 22:47

Couple of Decent Track shots and a side on PCB one of the Standard Model here in this ebay listing -
http://cgi.ebay.co.uk/SPACE-DRUM-Vintag ... 53e487cf87

Seems to have a trimmer in it which isn't on the schematic

Scruffie · Post by **Scruffie** » 29 Nov 2010, 23:59

Scruffie wrote: Seems to have a trimmer in it which isn't on the schematic

Scratch that, yes it is.
(Was too late to edit)

JuliaDee · Post by **JuliaDee** » 19 Feb 2011, 03:17

As a historical footnote, here's the original schematic from my notebook. The drawings and most of the text is in my handwriting, but there are a few notes and a couple of revisions in someone else's - I think Mike had Howard Davis give it a once-over just before production.

julia

spacedrum.pdf: EH-5300 Space Drum and 5350 Super Space Drum; (1.4 MiB) Downloaded 613 times

borislavgajic · Post by **borislavgajic** » 19 Feb 2011, 23:27

http://electroharmonix.vintageusaguitar ... &Itemid=55

Hides-His-Eyes · Post by **Hides-His-Eyes** » 20 Feb 2011, 10:39

If you don't mind a couple of questions...

If you were using a transformer in the unit anyway, why not go full on Bipolar?

Did RCA make you your own branded 'EH' OTA chips?

uncleboko · Post by **uncleboko** » 20 Feb 2011, 12:35

Correct me if I'm wrong, but the Start Frequency pot wiper connects to pin 3 of the CA3094 and the Stop Frequency pot wiper connects to pin 12 of the 324. Also I think that the common legs of the two pots connect to +9v.

Also note that the other common legs of these two pots have a 15k or is it 13k resistor hanging down to ground, whereas the standard Space Drum has 3 x 1N4148 diodes.

Many thanks for the clean version of this circuit after all these years.

uncleboko · Post by **uncleboko** » 20 Feb 2011, 12:36

uncleboko wrote:Correct me if I'm wrong, but the Start Frequency pot wiper connects to pin 3 of the CA3094 and the Stop Frequency pot wiper connects to pin 12 of the 324. Also I think that the upper common legs of the two pots connect to +9v.

Also note that the lower common legs of these two pots have a 15k or is it 13k resistor hanging down to ground, whereas the standard Space Drum has 3 x 1N4148 diodes.

Many thanks for the clean version of this circuit after all these years.

Previous post corrected .

Scruffie · Post by **Scruffie** » 20 Feb 2011, 15:53

Regards this circuit, someone contacted me recently and has kindly converted it to the LM13700 for me and provided a schematic and PCB layout to share (Thanks Andreas if you're reading this).

So here's the schematic, i'll post the layout up when I find the time (And work out Eagle!)

Hides-His-Eyes wrote:If you don't mind a couple of questions...

If you were using a transformer in the unit anyway, why not go full on Bipolar?

Did RCA make you your own branded 'EH' OTA chips?

The Big Muff style chassis version of this pedal (Not the Super Version) Didn't use a Transformer, so that's probably your answer.

And I imagine RCA did, I have some house numbered parts of there's laying around from some other stuff.

Hides-His-Eyes · Post by **Hides-His-Eyes** » 20 Feb 2011, 17:08

Is the 13700 conversion just pin numbers or is it adding things like Ibias?

Is there a good page to learn about OTAs? I know the purpose but not the application.

JuliaDee · Post by **JuliaDee** » 01 Mar 2011, 17:12

Hides-His-Eyes wrote:If you don't mind a couple of questions...

If you were using a transformer in the unit anyway, why not go full on Bipolar?

Did RCA make you your own branded 'EH' OTA chips?

The original had to run on batteries or external adapter, so single-ended was simpler/cheaper. For the second generation, I dunno... I guess it was easier just to keep what already worked. With Mike if you ever changed anything he would forever claim that the original sounded better, lol. And full bipolar would have meant another regulator...

Yes, RCA just put the EH1048 designation on standard CA3094's for us. At the beginning it was a bit of a trade secret.

julia

JuliaDee · Post by **JuliaDee** » 01 Mar 2011, 17:18

Hides-His-Eyes wrote:Is the 13700 conversion just pin numbers or is it adding things like Ibias?

Is there a good page to learn about OTAs? I know the purpose but not the application.

I haven't done anything with OTA's in a while but yes the 13700 is pretty much a drop-in for the 3094. Ibias is optional but can definitely reduce distortion if that's what you're looking for. The National datasheet/app notes for the LM13700 are a good place to learn. The original RCA databooks were good too but long gone. Also

http://en.wikipedia.org/wiki/Operationa ... _amplifier

julia

JuliaDee · Post by **JuliaDee** » 06 Mar 2011, 01:31

Hides-His-Eyes wrote:Is there a good page to learn about OTAs? I know the purpose but not the application.

I've scanned and uploaded the RCA OTA (CA3080 and CA3094) app notes from the 1983 "Linear Integrated Circuits and MOSFETS Application" book to these locations:

http://www.pragmaticdesigns.com/RCAAppN ... CA3080.pdf

http://www.pragmaticdesigns.com/RCAAppN ... bility.pdf

http://www.pragmaticdesigns.com/RCAAppN ... lifier.pdf

At the time these were "the Bible" on OTA's and they're still a great reference. Semiconductor companies appreciated the value of good app notes in those days. There's even a nice little tutorial on current mirrors at the end of ICAN-6668.

Hope this is useful.

Julia

Hides-His-Eyes · Post by **Hides-His-Eyes** » 06 Mar 2011, 01:36

That's absolutely fantastic julia, I look forward to reading through them. Thank you so much!

JuliaDee · Post by **JuliaDee** » 06 Mar 2011, 01:38

JuliaDee wrote:
Hides-His-Eyes wrote:Is there a good page to learn about OTAs? I know the purpose but not the application.
I've scanned and uploaded the RCA OTA (CA3080 and CA3094) app notes from the 1983 "Linear Integrated Circuits and MOSFETS Application" book to these locations:

http://www.pragmaticdesigns.com/RCAAppN ... CA3080.pdf

http://www.pragmaticdesigns.com/RCAAppN ... bility.pdf

http://www.pragmaticdesigns.com/RCAAppN ... lifier.pdf

At the time these were "the Bible" on OTA's and they're still a great reference. Semiconductor companies appreciated the value of good app notes in those days. There's even a nice little tutorial on current mirrors at the end of ICAN-6668.

Hope this is useful.

Julia

Hm, the link to ICAN-6077 was apparently too long; I've renamed the file. Let's try

http://www.pragmaticdesigns.com/RCAAppN ... bility.pdf

Julia

inlifeindeath · Post by **inlifeindeath** » 25 Mar 2011, 14:36

hey all,
i've now cloned both the Crashpad and the Super Space Drum, thanks to the help of Scruffie and Julia! I'll put some video up asap.

drbob1 · Post by **drbob1** » 26 Mar 2011, 16:56

I had an AC powered space drum (since sold) and the AC powered Super Space Drum for years. I don't really have much use for them, just could never see getting rid of them. Asked Mike about them once, especially the "Coordinator Input" and he swore he couldn't remember anything about it: not who designed it, what it did or anything else. Thanks so much Julia for helping sort out what these were. I'd love to see someone make music with the whole system!

JuliaDee · Post by **JuliaDee** » 26 Mar 2011, 17:11

The "Coordinator" just allows you to inject an external signal into the Space Drum's VCA in place of its internal oscillator. Hitting the pad will then initiate a burst of the external signal with an exponentially-decaying envelope.

Full details of the Clockworks coming soon, stay tuned...

julia

drbob1 wrote:I had an AC powered space drum (since sold) and the AC powered Super Space Drum for years. I don't really have much use for them, just could never see getting rid of them. Asked Mike about them once, especially the "Coordinator Input" and he swore he couldn't remember anything about it: not who designed it, what it did or anything else. Thanks so much Julia for helping sort out what these were. I'd love to see someone make music with the whole system!

Scruffie · Post by **Scruffie** » 26 Mar 2011, 17:19

JuliaDee wrote:
Full details of the Clockworks coming soon, stay tuned...

julia

Now this i'm looking forward to

&

inlifeindeath wrote:hey all,
i've now cloned both the Crashpad and the Super Space Drum, thanks to the help of Scruffie and Julia! I'll put some video up asap.

And Hey! Great to hear you got them working, can't wait to see what you came up with, I really must get to making some of these.

JuliaDee · Post by **JuliaDee** » 26 Mar 2011, 19:30

Clockworks info posted in a new topic at

https://www.freestompboxes.org/viewtopic.php?f=1&t=12667

Enjoy

Julia

Scruffie wrote:
JuliaDee wrote:
Full details of the Clockworks coming soon, stay tuned...

julia
Now this i'm looking forward to

EHX - (Super) Space Drum (Percussion Effect) [schematic]