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High-current supplies for Solenoid Drawstops?

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NeilCraig

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High-current supplies for Solenoid Drawstops?

PostMon Mar 21, 2005 4:59 pm

Dear All

I don't seem to be getting anywhere with my console rebuild at present, other than stripping, sanding and varnishing. Main stumbling block is the high-current capable PSU for the drawstop drivers.

The darlington boards are easy, I can get those from Jordan but I am going to need 4 banks of 32 darlington drivers which means 4 x 32 x 0.5A = 4 x 16A. I am pretty sure I can divide the power input to the Darlington boards to allow me to use multiple smaller supplies, but I'm still at a loss as to how to proceed. I could build something from directions and a circuit diagram but...

Anyone any ideas? Ron Coates said he had an old KA 10A supply but even with extra capacitors it was not suitable for 64+ drawstops. :o(

Best wishes//Neil
A plaque is simply not necessary - everyone will know it is a Willis organ! - "Father" Henry Willis
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Marco

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Re: High-current supplies for Solenoid Drawstops?

PostMon Mar 21, 2005 5:14 pm

NeilCraig wrote:Anyone any ideas? Ron Coates said he had an old KA 10A supply but even with extra capacitors it was not suitable for 64+ drawstops. :o(


any big(er) electronic store should have power supplies that can handle that I'd assume, the store I used for my reed switches lists a 36A/13.5VDC (500W) power supply for example. Although you might be looking at quite an expense for something that can handle 64A (I'd say a grand easily).

In any case, do you really expect to engage ALL drawknobs at the exact same time? If you could do this in groups you'd lower quite a lot the peak amperage you'd need (say, engage all of the swell, then the hw, etc. etc.).

I think Martin could also easily code in HW2 something like (x,y,z are user configurable obv.) 'if this combination engages/disengages more than x amount of stops, send the state changes for y stops every z milliseconds' (you could do 10 stops at a time every 100 milliseconds, say, lowering your peak amperage to 5A rather than 64).
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ReinerS

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PostTue Mar 22, 2005 5:15 am

Hi Neil,
a very simple idea might be to get an old car battery and add a charging unit (shouldn't cost you much). The battery will EASILY handle your 64 amps, just be sure not to produce a short! The charging device will probably only need to supply a max of 5A to keep the battery charged, it should have an electronic regulation so that it can be kept on all the time.

Greetings
Reiner
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imetier

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PostTue Mar 22, 2005 5:58 am

Hi Neil,

I would not recommend using a car battery since it has a limited lifetime.

It is true that electronics providers usually have powerful power supply units. I found one capable of providing around 10 Amps (if I remember well) quite cheap.

Marco's idea can be interesting, however solenoids usually require quite a long impulse to operate - you can check this for your drawstops. Anyway, the MIDI bus already introduces a small delay (in the order of 1ms) between commands.

Greetings
Jean
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ReinerS

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PostTue Mar 22, 2005 6:06 am

limited lifetime of a car battery is true, but given that the organ is in a living room and so the battery is not subjected to freezing temperatures and also the loads are much lower than in your car, I would guess that you should have at least 10 years of usable life. Just make sure its the maintenance free type.
Of course a high current power supply is more elegant, but its a matter of cost. It will definitely cost several 100€s.

Greetings
Reiner
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SMann

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PostTue Mar 22, 2005 11:27 am

Reiner,

I would just add that Neil should be sure to keep a good set of jumper cables close by at all times in case the battery goes dead unexpectedly before a performance and he has to ask one of his neighbors for a "jump".


Sorry... I just couldn't resist!


Steve
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3dOrganist

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PostTue Mar 22, 2005 11:55 am

I have seen standard organ console power supplies, even some more modern types, on ebay and KeyboardTrader occasionally. They are relatively rare, but I picked up a Peterson unit on ebay at a reasonable price.

Mark
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NeilCraig

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PostTue Mar 22, 2005 4:02 pm

Hi All

Thanks for the responses. I had initially thought of using a Lead-Acid battery but dismissed it as "nuts" but considering that I can get one suitable for starting a diesel engine for about 50 quid and even with "my" kind of registrations how many times am I going to change pistons in a 2-hour practise session...It's workable.

10A supplies sound okay, until the cost is looked at and then that I would need four of them. At some point I will be building a new "portable" 4-manual console along the lines of Skinner's "folding-jambs" design with 80+ drawstops and LED'd piston couplers along the front, so having the power source as an easily-removed sealed battery would be very useful.

Right, I think it's time to put this plan on paper...

Thanks again!

Best wishes//Neil
A plaque is simply not necessary - everyone will know it is a Willis organ! - "Father" Henry Willis
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Jim Reid

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PostTue Mar 22, 2005 5:04 pm

CAUTION ..........

Radio amateurs have learned long ago, the hard way, that
using a Lead-Acid battery indoors at home can be a tragic
mistake. They "outgas" toxic fumes which can cause a good
deal of harm!! Such batteries have also been known
to catch fire and burn an amateur's home; I do not know the
chemistry involved, but it is an absolute no-no among the
ham radio crowd. Some amateurs place them outside, in
the open air, and run very heavy conductors into the house
to their radio gear. Often, here in Hawaii, the batteries
are maintained at charge via solar panels; some homes being
entirely on battery/inverter power systems. But the
batteries are always outside the home living area!

In the US at least, an outfit called Astron builds a line of
power supplies for use to replace/instead of batteries.
I had a couple of their 70 amp (peak output) continuous
output of 50 amps. Their RS-70A unit is rated at 70 amps,
surge; 57 amp continuous service. Price, $290. They can
be connected in parallel for even more output current to
a load. I had such a pair at one time, but have long since
sold them. Perhpas such units are used in the UK by the
amateur radio group; of course the primary AC input will
be different in the UK from the 120 VAC, 60 Hz home power used
in the US. There are a few thousand radio amateurs in the UK,
so must be one near to you, ask about what they, or their radio
friends are using instead of batteries for their rigs.

But, DON'T use a lead acid battery sitting on the floor behind
your organ set up in doors!

Be careful.....
Jim Reid
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NeilCraig

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PostTue Mar 22, 2005 7:21 pm

Hi Jim

I was under the impression that they gave off hydrogen during charging and tend to explode if they're dropped on concrete (I know someone round here was killed when they dropped a pallet carrying a battery from a 32-ton truck) but not during use. You do have a valid point though (which I'd forgotten) that spark generation by electronics could have dangerous repercussions.

Okay, back to the drawing board. Again. I remember Yves told me he had designed a unit drawstop driver which did not require a very heavy duty PSU because its circuit included capacitance sufficient to drive a single drawstop. I'll ask him about it again.

Best wishes//Neil
A plaque is simply not necessary - everyone will know it is a Willis organ! - "Father" Henry Willis
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MidiOrganMan

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Re: High-current supplies for Solenoid Drawstops?

PostTue Mar 29, 2005 2:06 pm

Hi Craig,

I used a car battery to power my organ console for about 5 years without any problems whatsoever. The battery was trickle charged when the console was on. I was of course aware of the hydrogen problem but figured that it wouldn't be a problem with very low charge rates and intermittent use. The battery was located under the console's plinth. An 110V AC relay activated through a X-10 system control unit allowed the console to be switched on remotely. This relay isolated the console from the battery when not activated.

I have recently replaced the car battery with a Sorensen SRL 10-100 series regulated power supply which is rated to deliver 100A at 10V. The console and all the MIDI stuff added to it only consume about 3A until the stop and coupler solenoids are actuated simultaneously in which case the current drawn is approximately 150A. Originally the console was fed by a 3-phse rectifier rated at 150A. The console has 5 manuals and 200 stops and couplers!

I did a couple of simple modifications to the Sorensen power supply. The first was to increase the output voltage to 12V by adding a resistor to the appropriate terminal block on the back of the unit and the second was to disconnect the cooling fan which I figured was unnecessary with such a low load. This has been working fine for about two months. My concern that this single supply would not operate all 200 stops and couplers at the same time proved to be unfounded as the Sorensen has a bank of 8 x 85,000uF electrolytic capacitors. The output current meter swings momentarily to about 65A only.

I think there is no reason not to use a car battery, at least temporarily, if one follows a few basic rules:
1. Don't locate it in a confined space without ventilation
2. Don't ever allow its ouput to be short-circuited
3. Don't overcharge the battery
4. Don't allow smoking nearby
5. Don't leave the battery trickle charging continuously
6. Do provide a heavy duty manual switch or relay so that the battery can be disconnected from the console when not being used to power it.

BTW the Sorensen SRL 10-100 weighs 132lbs (59.8kg) so it's quite a back-breaker! I had to install some lifting tackle in my garage to lift the supply onto the workbench for servicing and modification.

Regards

Martin Lilley
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3dOrganist

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Re: High-current supplies for Solenoid Drawstops?

PostTue Mar 29, 2005 2:49 pm

MidiOrganMan wrote:I have recently replaced the car battery with a Sorensen SRL 10-100 series regulated power supply which is rated to deliver 100A at 10V. The console and all the MIDI stuff added to it only consume about 3A until the stop and coupler solenoids are actuated simultaneously in which case the current drawn is approximately 150A. Originally the console was fed by a 3-phse rectifier rated at 150A. The console has 5 manuals and 200 stops and couplers!
...snip...
BTW the Sorensen SRL 10-100 weighs 132lbs (59.8kg) so it's quite a back-breaker! I had to install some lifting tackle in my garage to lift the supply onto the workbench for servicing and modification.

Wow! That's what I call a power supply!!

I was able to snag a Peterson Pulse Power Supply on eBay. It is documented to be able to handle 64 stop tablets or 40 drawknobs (20 ohm coils). It is physically small and lightweight, and I can carry it easly in one hand. I play a small pipe organ at church (19 ranks) and I don't need a bigger one for practice at home. So this little guy will fill the bill for me.

Mark
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NeilCraig

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PostTue Mar 29, 2005 2:54 pm

HI Martin

Okay, since I'm having no fun at all with Sonar (it is just taking up valuable practice time!), how about using a couple of heavy-duty PC PSU units? Tagan produce some which can sustain 32A output on the 12V rail.

One of these should cope with my current 56 drawstops and two would suffice when my eventual 4-manual 90 stop beast is built.

Or am I missing something (other than how to keep the PSU rails up and I think I know the answer to that).

Best wishes//Neil
A plaque is simply not necessary - everyone will know it is a Willis organ! - "Father" Henry Willis

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