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Controlling SAMS on and off mddp128 MGB

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dw154515

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Controlling SAMS on and off mddp128 MGB

PostMon Sep 27, 2021 10:09 pm

I am considering doing a project and controlling the SAMS (from a Rogers Olympic T/O console) using a MidiBoutique MDDP128 board to drive the SAMS. I have used the mddp128 to drive LED's on/off. That's easy enough.

My question....

I get how to turn the SAM "ON." That is easy enough. In MIDI settings for that tab, you set the MIDI note on to correspond to that particular tab.

However, how do you then turn the SAM "OFF"?

Do you utilize another output from the MDDP128 to power the "off" side of the coil? And if so, how do you send another "NOTE ON" command when the stop is actually turning "OFF."

Or is this reversing-action built into the SAM itself?

I do not currently have the instrument in my possession. I am asking preemptively.

Any ideas/clarification would be helpful!
Drew A. Worthen
Master of Music in Composition - Butler University
http://www.drewworthen.com
Director of Music & Website Admin - Greenwood UMC
http://www.greenwoodumc.org
Field Engineer - Diversified (Formerly Sensory Technologies)
http://www.sensorytechnologies.com
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engrssc

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Re: Controlling SAMS on and off mddp128 MGB

PostTue Sep 28, 2021 12:48 am

My experiences to control SAMs is with controllers from Midi Hardware with drawknob organs. Basically the same setup with moving tabs..

https://www.midi-hardware.com/index.html

I'm sure you realize that the SAMs has 2 coils, one for on (stop head out) and one for off ( stop head in).

Using a BBS-1K

https://www.midi-hardware.com/?section=prod_info&product=BBS-1K

All 64 input contacts can be programmed to send note-on ONLY and on a second BBS-1K
all 64 input contacts can be programmed to send note-off ONLY This will tale care of the inputs from 64 SAMs contacts (one contact when you pull the stop and one contact when you push the stop.

Alternately half of the inputs (32) of a BBS-1K can be programmed to send note-on ONLY, while the other half (32) can be programmed to send note-off ONLY. This will tale care of the inputs from 32 SAMs contacts (one contact when you pull the stop and one contact when you push the stop.

Using a MIDECO

https://www.midi-hardware.com/?section=prod_info&product=MIDECO

MIDECO set to mode = 13h: SAM - Stop Action Magnet control, MIDECO then works with only 32 notes because outputs are paired.

When a note-on is received, it triggers an output pulse (connected to the "on" coil)
When a note-off is received, another output pulse (connected to the "off" coil) is triggered

Pulse length defined by the Duration Parameter.

When a MIDECO is used for SAMs, a high power (add on) accessory is used for switching high currents to GND.

https://www.midi-hardware.com/?section=prod_info&product=MIBO

Obviously the note (and MIDI channel) received by a MIDECO decoder input has to be programmed to be the same note (and MIDI channel) as sent by the BBS-1K encoder. :wink:

Rgds,
Ed
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Re: Controlling SAMS on and off mddp128 MGB

PostTue Sep 28, 2021 10:19 am

The DP64 driver boards are needed to use the MDDP128 boards with SAMs. I am not seeing the details for selecting the correct sets of boards that used to be on the Midi Boutique site. They probably made the best decoders and certainly still list a few dozen model variations but I have no idea whether the current staff at Midi Boutique have the founder's expertise to ensure you get the correct boards.

As Ed says there will two drivers per SAM and with the DP64 drivers you end up with all the ON coils connected to one row of screw terminals and all the OFF coils on another row. I am thinking that one mddp128 get's a piggyback board to drive two DP64's to handle 64 stops (128 coils) but I last did this exercise over five years ago so I may be wrong.
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Re: Controlling SAMS on and off mddp128 MGB

PostTue Sep 28, 2021 10:42 am

I had ordered one mddpuN/dp128P and one mddpuN/dp64P to handle up to 96 stops on a Rodgers 32x where I had converted the two power supplies to +16V -- they were originally -16V. That combination gave me two of the main boards, one piggyback board (part# ??) and three DP64 boards. It's a great combination for about $500.
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engrssc

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Re: Controlling SAMS on and off mddp128 MGB

PostTue Sep 28, 2021 12:01 pm

The difference between piggy-backing two MIDECO boards ($120)
or using one MIDECO board and one MIBO is $18 USD.

The second setup would be preferred. It would be fiddly to try to piggy-beck two MIDECO boards.

The "trick all this is the decoder sending the correct pulse. Another consideration is the instantaneous current draw needed.

Somewhere I recall a plan to control SAMs sequentially. It might be fun to watch. (Starting left to right around the stop board(s maybe?). Probably sound a little like a machine gun vs that more conventual thud. :roll:

Rgds,
Ed

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