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Supplying Console Power

Building organ consoles for use with Hauptwerk, adding MIDI to existing consoles, obtaining parts, ...
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flydeltajets

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Supplying Console Power

PostSun Oct 15, 2017 8:08 pm

Hello all,

I'm curious if anyone has experience/suggestions for wiring console power?

My console requires 2x 70A Astron power supplies for the drawknobs, wired in parallel, and each needs a dedicated outlet/circuit. My idea is to wire 2 relays through a single 12V switch in order to provide simpler power-on.

Do the relay (link below) and attached wiring schematic look like they would work OK, or do I need to come up with a different plan?

Relay: http://www.mouser.ie/ProductDetail/Omro ... 252bSoww==

Schematic idea:
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jkinkennon

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Re: Supplying Console Power

PostMon Oct 16, 2017 10:21 am

You have a working arrangement there to switch the power. That particular solid state relay requires a heatsink to provide more than 5A to a power supply. I'd be conservative and put the pair on a heat sink or perhaps just a metal enclosure with thermal grease even if running at 220V.
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ldeutsch

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Re: Supplying Console Power

PostMon Oct 16, 2017 10:51 am

My theater organ console has 160 SAMs that work easily on a single 70A Astron supply. Are you absolutely certain you need two of these?

Les
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rhedgebeth

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Re: Supplying Console Power

PostMon Oct 16, 2017 11:07 am

Do be reminded that the over current protection on the Astron supplies is "crowbar", i.e. when it reaches the rated limit it shuts down - completely. It does not auto reset. You have to power it off then back on manually. I much prefer constant current protection myself. I've had several emergency service calls for this problem with the Astrons over the years. This has generally happened at the worst possible time, major service, concert or the like. Very wise to have plenty margin with the Astrons! I no longer use Astron supplies for this reason (and others).
Richard S Hedgebeth
Westminster Organ Works
Authorized Hauptwerk reseller
http://Westminsterorganworks.com
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flydeltajets

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Re: Supplying Console Power

PostMon Oct 16, 2017 11:19 am

Thanks, jkinkennon, I didn't realize the part about the heatsink, but will definitely include one of those now.

Les, I could definitely be wrong. My console is similar in size (~160 SAMS) plus about 10 lighted pistons which are on at any given time. Based on everything I've read, the power supply should be sized for 1/2 amp per SAM (i.e. 80A) plus approximately 5-10A drawn from the encoders, key contacts, and piston lights. Adding a 35% safety margin puts me around 120A. I agree that 140A is a bit overkill, but the 70A models are the only ones that permit parallel wiring.

I'm definitely open to other ideas as far as supplying the power, but I already have a "free" 70A supply that came with the console.

Is there something I'm missing or miscalculating?

Thanks!
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ldeutsch

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Re: Supplying Console Power

PostMon Oct 16, 2017 5:46 pm

I did a very simple Ohm's law calculation to estimate the power draw in my console. I already knew the draw specified by my controller cage and I assumed the lights (which are all LEDs) were negligible. My audio system uses powered monitors and they are plugged into a different house outlet, as is my computer system - so they do not count in the calculation.

My SAMs (Reisner) have 30 Ohm coils ad only one of each pair can be fired at one time using the 12V supply, Hence, Ohm's law results in a requirement of 66 Amps for 165 SAMs. Although my final design had only 160, I had at one time planned for 165.

I have had my console in operation for almost five years with no power faults or any issues with the Astron 70A supply (other than its extreme mass!) It makes quiet a nice "bang" when I cancel loud registrations - but my house lights do not dim and I have never blown a circuit breaker!

There is another, more important issue you need to consider. Depending on the driver boards your are using to fire your SAMs, there is likely a limitation on the number of SAMs per board. You will have to wire the commons on your SAMs in such a way that they are isolated between these groups. Check with the supplier for your driver boards to see what, if any, restrictions there are.

It pays to do your design work and theory up front ...

By the way, you can see the blog I used to document my own console build at

http://www.nightbloomingjazzmen.com/Theater_Organ_Project.html

perhaps something else there might be helpful to you. If my experiences can save someone else making similar mistakes, then I have been successful.

Les
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Grant_Youngman

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Re: Supplying Console Power

PostMon Oct 16, 2017 11:20 pm

Peterson makes a Pulse Power Supply, designed specifically for SAM use. So specific in fact, that you can't use it for anything else, since a 20 second current draw of any kind will shut it down. It appears to be based on a lower current switching power supply used to provide the charge to a few farads of super capacitor (guessing) to deliver the relatively low duty cycle current pulses required.

Probably expensive, and only 40 draw knobs (or 64 30-ohm tabs) per unit. But … purpose built, and likely doesn't carry some of the baggage that comes with Astron.

Personally, if you're using the Astrons, I'd try to split the power so that you don't have to parallel the supplies. 140-150A at 13-14 volts can do a lot of damage if something goes wrong or you get fingers (the ones you may not have anymore) across the hot leads. If you don't (and you may, not saying you don't) have experience dealing with low voltage power distribution at that current level you might want to get some assistance to make sure wiring, distribution blocks, etc aren't underrated.
Grant
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NickNelson

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Re: Supplying Console Power

PostTue Oct 17, 2017 3:53 am

Grant_Youngman wrote:140-150A at 13-14 volts can do a lot of damage if something goes wrong.


Certainly, that would make a pretty respectable arc welder.

Nick
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organsRgreat

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Re: Supplying Console Power

PostTue Oct 17, 2017 7:58 am

arc welder . . . :lol:
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ldeutsch

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Re: Supplying Console Power

PostTue Oct 17, 2017 9:33 am

I am not a welder - but I AM an expert on communication with spacecraft at other planets. A couple years ago I visited a university in Kentucky where they were outfitting a 21 meter (which I consider quite small) parabolic antenna to communicate with spacecraft as far away as our Moon. While touring the transmitter area I noticed that the power supply they had installed for their transmitter was the identical Astron 70A supply I had used in my theater organ console!

In fact, the main application for these seems to be ham radio transmitters.

Les
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TheOrganDoc

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Re: Supplying Console Power

PostTue Oct 17, 2017 4:46 pm

My 90 Stop (Sam's), {MeliTzer} has been working beautifully for 8 Years utilizing a (12volt/1.5 Amp) power pack connected to "Two Huge Capacitors, connected in parallel to drive my Sam's, (Fuses at all critical points.)

The only time that they require an extra piston push, is when testing, (with every stop actuated) ! ! ! :D

I am most happy with this setup, No problems, and inexpensive i
Mel, TheOrganDoc
Mel..............TheOrganDoc...............
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flydeltajets

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Re: Supplying Console Power

PostTue Oct 17, 2017 8:19 pm

Thanks everybody for the input and feedback. This has opened up several new thoughts for my situation...

Along the idea of the Peterson pulsed power supply...would it be possible and/or advisable to use my current power supply and put capacitors (and diode?) in front of the stop action but wire the continuous draw items 'straight'...i.e. for the knobs, the system would be wired: Rectifier ->(Diode?)->Capacitor->SAM bank->Rectifier Ground. My thought process is that the capacitor could store up enough current for 2 full drawknob cycles. In this scenario, I'd have 4 separate (parallel) circuits off the rectifier...a constant-on circuit for the LEDs and encoders, plus 3 circuits with capacitors (each jamb plus tilt tab assembly).
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Frank-Evans

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Re: Supplying Console Power

PostTue Oct 17, 2017 9:38 pm

I guess I have to stick my nose in here also.... I have 215 SAMs on my console... the coils are 28 ohm and I assume they were sold by Syndyne.. anyway they came off of a couple of Rodgers organs... The first power supply I used was the original Rodgers 340 with a couple of 130,000 Mfd caps....Fired all of them with no problem but the supply did put out 18 volts, I used diodes to drop it to 13 volts and it still worked very well... You just don't need those massive hunks of iron to do the job... I recently replaced the power supply with 4 ea. 35 amp 12 volt switch mode power supplies. I have them adjusted to 12 volts... The real secret is in how long you hit the SAMs with voltage... My driver boards (Artisan) can be programmed to any length pulse from 50 ms to 250 ms..I have the system set at 100 ms. The rest of the time there is no load on the power supply at all. I have never seen the power supply fans come on and the cases all stay at room temperature...
The times that a pipe organ console was converted to SAMs and integrated into the organ there was a different set of requirements since most times the voltage was applied as long as the piston was held..
Modern technology has changed all that....... just my $0.02 worth...

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