Relay question

[Guest]

<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>I have a situation that is new to me.<SPAN style="mso-spacerun: yes"> </SPAN>Since I have not built my own relay systems before, I need some advice here.<SPAN style="mso-spacerun: yes"> </SPAN>I just acquired a console that I would like to use for my organ.<SPAN style="mso-spacerun: yes"> </SPAN>The console has a relay that I am not familiar with.<SPAN style="mso-spacerun: yes"> </SPAN>I believe that the console is a Bennett.<SPAN style="mso-spacerun: yes"> </SPAN>It has no part on it for the stops to control.<SPAN style="mso-spacerun: yes"> </SPAN>I am guessing that the original organ had the type of chests where a magnet is activated when a stop is put down, thus letting pressure into the chest.<SPAN style="mso-spacerun: yes"> </SPAN>I can’t remember what these are called.<SPAN style="mso-spacerun: yes"> </SPAN>I have not worked with them before.<SPAN style="mso-spacerun: yes"> </SPAN>I am using unit electro-pneumatic chests.<SPAN style="mso-spacerun: yes"> </SPAN>Please tell me if this would be safe/ok to do.</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT size=3><FONT face="Times New Roman">I am thinking about having the stops actuate a switch that will connect the ground to each rank.<SPAN style="mso-spacerun: yes"> </SPAN>Then, when the stop is turned off, the ground will disconnect.<SPAN style="mso-spacerun: yes"> </SPAN></FONT></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Would this work?<SPAN style="mso-spacerun: yes"> </SPAN>Would it be safe?<SPAN style="mso-spacerun: yes"> </SPAN>Have other people done this?</FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Thanks!</FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face="Times New Roman" size=3>Luke</FONT></P>

[FrenchHorn8]

Re: Relay question



Luke, this would only work with a straight organ, and you would have to have to install a diode in series with each magnet.  I would suggest you build a diode matrix relay.  If you're not up to that, I have a very nice Wurlitzer Style E relay... it may need a few wires replaced though.... </p>

[Guest]

Re: Relay question

I am actually going to set it up as a straight organ and see how it works out. Adding a few ranks from the other organ just acquired. I am just curious, why the need for a diode for each magnet? This the the kind of thing I was wondering about and would like to learn more about the electronic side of it all.

[Guest]

Re: Relay question



When the ground switch is open, the magnet coils are still all connected together. If a key is pressed putting voltage on one magnet, it will go to the others.</p>

The way the individual magnets are isolated before electronics is to use a separate key contact for each note and use a 61 note switch to connect the key contacts to the chest magnets. The diodes achieve the same purpose electronically of isolating each magnet from the others. This method requires a key contact for each set of magnets. On an using pitman chests (common magnet for all the pipes at the same pitch), separate key contacts are used primarily for couplers. If many separate ranks are to be controlled by the same keyboard, a relay is used to expand the number of contacts available.</p>

There are many ways to use electronics to accomplish the same purpose. I have used 61 note switches isolated with diodes for expansion of the number of stops on my organ. Using this method does not require adding a relay. Adding a few stops (2 or so) this way is fine, be sure that the key contacts are not overloaded, for example do not use this method with Wicks direct electric magnets which have a greater current drain.</p>

For higher currents, a transistor buffer which acts as a relay to isolate the key contacts is necessary. If silver key contacts are used, a voltage fo about 12 volts is optimum with a current drain of 10 to 50 milliamps (240 to 1200 ohms load resistance). The threshold breakdown voltage for silver oxide is about 5 volts and the minimum current is required to clean the contacts. Gold contacts can use low voltages (5 volts) and require a lower current drain (less than 10 milliamps).</p>

My organ uses silver contacts with 180 ohm magnets and a 12 volt power supply. This combination has proven to be highly reliable and has been in service for 81 years with the original contacts.</p>

I hope this helps somewhat in explaining the nedd for diodes (or a relay) to isolate the magnets. Audsley's book also explains these issues.</p>

</p>

[Jay999]

Re: Relay question



To keep from starting a fire in your console, you should not attempt to ground a whole series of magnets under one stop back through the stop key contacts.There should be only one circuit active to your chest magnets...that is the circuit that a key (or a relay contact) turns on in order to permit voltage to the chest magnet.</P>


Also, it is not safe to run grounds and positives together in the same cable bundle.</P>


Your rectifier has a fuse that will blow, in the event of a short. However, it takes several amps (usually a direct short) to blow that fuse. If two wires are slightly touching, with a "tease" of insulation open, the two wires will create a minor short...enough to turn them white hot, yet not enough to blow the rectifer fuse.</P>


Please, don't try to reinvent the wheel...go with conventional switching and be safe. If you need relay components to do your job, just say so....there are several guys on this forum that either have relays available, or know who can provide them for reasonable costs.</P>

[Jay999]

Re: Relay question



Dear Harding....a kindly suggestion after that rather "up tight" lecture that I wrote you....</P>


I have one friend just above Milwaukee that has a complete reisner (electro-mechanical) relay he's willing to give away. It's a theatre organ relay, so there's oddles of extra relay switches, and stop switches there. It would be more than enough equipment for you to build a fine unit system for a house organ.</P>


If you're interested, just let me know.</P>


Best wishes...</P>

[Don Furr]

Re: Relay question

[quote user="Jay999"]

Dear Harding....a kindly suggestion after that rather "up tight" lecture that I wrote you....</p>


I have one friend just above Milwaukee that has a complete reisner (electro-mechanical) relay he's willing to give away. It's a theatre organ relay, so there's oddles of extra relay switches, and stop switches there. It would be more than enough equipment for you to build a fine unit system for a house organ.</p>


If you're interested, just let me know.</p>


Best wishes...</p>

[/quote]</p>

Reisner relays do take a lot of time to wire up, solder and adjust but once you've done all that it's pretty much trouble free. My entire organ is Reisner. Since it's not a straight organ I've soldered diodes on every single contact. That's what took hours and hours to do. I haven't had to adjust a relay in at least 2 years. It's a straight forward system that's easy to trouble shoot and maintain. And ....IT'S CHEAP!!!!!!</p>

BTW Jay, I ran across my FIRST new organ (big organ) installation that uses DE chest with only a single 61 wire cable going to the chest!!!! I know what I'm doing next time...lol
</p>

[Jay999]

Re: Relay question

Hi Don. Did they put the relays in the chest?

[Menschenstimme]

Re: Relay question



Hi Jay,</P>


Probably did. One of the chests of my residence organ is a 4-rank 61-note straight electro-mechanical chest with a 61-note cable (plus spares for the stop controls). Inside the chest is a driver board with Darlington transistors which drives up to 4 magnets at a time (per note). The stop control is by 4 61-note Peterson reversed-diode-array circuit cards with an automobile headlight relay to break ground (one relay per card). Rather clever and works very well.</P>


[I]</P>

[Don Furr]

Re: Relay question

[quote user="MenchenStimme"]

Hi Jay,</p>


Probably did. One of the chests of my residence organ is a 4-rank 61-note straight electro-mechanical chest with a 61-note cable (plus spares for the stop controls). Inside the chest is a driver board with Darlington transistors which drives up to 4 magnets at a time (per note). The stop control is by 4 61-note Peterson reversed-diode-array circuit cards with an automobile headlight relay to break ground (one relay per card). Rather clever and works very well.</p>


[I]</p>

[/quote]</p>

Bingo......that's exactly whats going on. For example all C1's are fired with a single wire and the stop control determines which return is made through a serirs of small relays. Makes sense to me. Sure beats wiring 61 notes on each rank!!
</p>

[Jay999]

Re: Relay question

From the chest driver card...is there an individual wire running over to each magnet...or are the four magnets being supplied by one wire?

[Menschenstimme]

Re: Relay question



Hi Jay: I have been thinking about this all evening. I assume you are referring to the following.</P>


Inside the chest is a driver board with Darlington transistors which drives up to 4 magnets at a time (per note). </P>


While I did the conversion from mechanical switching to the all-solid-state system described in my previous post, I did not change the original wiring from 1964 at all. I honestly don't remember the answer to what you are asking. The grounds are all individual, but I cannot remember if there are only 61 "plus" wires for the keying or one per magnet. My guess is that there are only 61. But never fear. This chest is over 40 years old and has been playing in its current (pun intended) configuration for several years now, for an average of at least 30 minutes per day, every day, with no electrical problems, overheated wires, etc.</P>


Hope this helps. Sorry I am not more specific.</P>

[Don Furr]

Re: Relay question

One wire feeds four magnets. The small relays determine which "return" get "made" according to which stop is drawn. I'm not sure how the backfeed issue is resolved. I haven't been inside the chest yet. It's solid state so I'm assuming there are diodes involved somehow. Remember this is on a NEW organ from a MAJOR builder. I think it's brilliant.

[Jay999]

Re: Relay question



Ok. That makes sense. The manual contacts are probably turning on a console computer circuit, with no more than 1/2 or so volts. That keeps the key contacts operating for a life time without burning. Then the console computer sends out it's digital information through a 6 wire shielded cable, (or possibly, if it's a Matters system, through a light transfer cable) to the chamber demultiplexer computer. Then...if the chest driver cards are using digital information to key them...another 6 wire shielded cable from the demultiplexer over to the chest driver. </P>


Probably the driver is powerful enough to turn on several magnets at one time, using a fairly heavy feed wire. The individual ground switches would carry the circuit... (or not...if the stop is off, and the switch isopen)... back to the rectifier.That would leave onlythe magnet feeds to be wired in the traditional 61 - 73 - 85 note configuration.</P>


Well, at the price of 100 conductor copper wire, that's quite a lot of savings in material, and hookup labor. As long as there is no possible way for a massive short to show up inside the chests, then it's a clever idea. This being a MAJOR builder,installing electro mechanical valves is quite interesting...as most of them feel that this type of valving system is way too expensive for a "straight" chest design.</P>

[Guest]

Re: Relay question



I'm a computer technician and have no trouble reading schematics but I just cannot get organ relays sorted out. Is a drawing available that shows key contacts, relays, relay contacts and chest magnets. (I'll leave combination actions for another day.) If not, would someone please be so kind as to make a drawing? I suppose there were differences between organ builders but there has to be a number of similarities as well.</p>

Thank you, </p>

</p>