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Guest Bud

Help with Rotary Switches

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Guest Bud

I read posts here frequently and cant help feeling a little envious of the fact that everyone has so much expertise in electronics. What I know about this subject can be written in block capitals on a postage stamp and there would still be lots of room for the portrait of Her Majesty the Queen.In an effort to learn, I built a panel using an old keyboard card. Within its limitations, it worked surprisingly well. I tried a second generation this time with a Hagstrom encoder and that worked even better. What I would now like to try is generation three, the main objective being to get the rotary switches to work as they should. Unfortunately I haven't a clue how to go about it.Having scoured months of posts, I'm not a great deal wiser - I don't even understand the terms used!! So, let me put my foot in it - can I ask this - with some trepidation. Is the solution as straightforward as wiring up the rotaries to a rotary decoder such as I spotted on one site which can turn signals into events which can be passed to a Hagstrom?If this is the case, how could I, for eg, use such a set up to implement, let's say an altimeter knob - would some sort of gearing be necessary ?I'm sorry to be so hopeless - just hoping someone will take pity on a newbie and help, or point me in the direction of advice.Thanks for 'listening'.Bud

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Guest

Hi Bud,it is not so difficult as it apperaes in the first moment.you have to distinguish between rotary switches and rotory encoders.the rotary switches have several positions and are soldered as serveal single switches. You use one common wire and for every positon one wire and connect them to the keyboardencoder. sample for this are the EFIS ND range selectors.for altutude , speed etc you use the rotary encoders. the encoders can be rotatet endlessly and they produce only an pulse every step you turn them. for this kind you need the rotary decoder wich translates these pulses into several closing actions like a switch. this can then be used from the keyboardencoder. hope i could help you a little bit.Achimhttp://a.bethke.bei.t-online.de

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Hi BudJust mail to hagstrom with your specifications. I know they sell addons for their encoders, at least I;ve heard that from someobe lese who did the same.You then wire the rotary encoder to that addon and that is connected to the keyboard encoderThat shoul dbe allhttp://home.wanadoo.nl/norbert.bosch

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Guest Bud

Many thanks guys. I'm encouraged to proceed with a new design. It will be a little time before I can proceed to build but I hope that I will be able to get further advice if it all goes pear-shaped.Bud

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Guest

Hi Peter, I have been to : http://www.knitter-switch.com but I did not know which of the encoders your were referring to in your post. Could you please post the part # if you have it. This is actually a very good solution and more cost-effective if you can use the encoders directly as it will obviate the need to buy or build another circuit to decode the pulses. thanks in advance,mofa

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Guest PANTU

Hi Bud,the type I referred to is the MRP 1-20 (look at "MRP series")There is 2 different versions available:the MRP 1-20 and the MRP 1-20 RPlease check which one suits your mounting best.Hope this helps.best rgdsPeter

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>Hi Bud, >>the type I referred to is the MRP 1-20 (look at "MRP >series") >There is 2 different versions available: >the MRP 1-20 and the MRP 1-20 R >>Please check which one suits your mounting best. >>Hope this helps. >>best rgds >>Peter That is the correct item number yeahHas anyone actually found a place that sells those for hobbyists and preferably does a mail order?Not the factory nor the finnish importer partner of them sells them to individuals, they only sell for manufacturers.. :-/Those units seem very nice and small compared to the ordinary rotary switches, so that they work nicely for "monitor behind plywood" -instrument panels etc..Tuomas

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Guest Bud

Many thanks - anything that will make construction easier is good for me.Bud

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Guest Bud

Hi Peter,I'm really grateful to you for taking the time to provide the heads up re Knitter-switch. I've now got some details - seems absolutely ideal. However, I can't quite get my head round how they should be used. Sorry to be so dense - and that's only one of my problems ! Could I impose on you further just to get clear what you were saying.I imagine I 've misunderstood but here goes. If I have terminals 7 to 9 free on my keyboard encoder, next to the common ground point, do I take it that all I have to do is to wire up the middle post of the rotary to the common ground and the right and left to, say, terminals 8 and 9 respectively and away I go into the far blue yonder, or have I got it completely wrong?Thanks Bud

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Guest Bud

Hi Peter,I'm really grateful to you for taking the time to provide the heads up re Knitter-switch. I've now got some details - seems absolutely ideal. However, I can't quite get my head round how they should be used. Sorry to be so dense - and that's only one of my problems ! Could I impose on you further just to get clear what you were saying.I imagine I 've misunderstood but here goes. If I have terminals 7 to 9 free on my keyboard encoder, next to the common ground point, do I take it that all I have to do is to wire up the middle post of the rotary to the common ground and the right and left to, say, terminals 8 and 9 respectively and away I go into the far blue yonder, or have I got it completely wrong?Thanks Bud

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Guest Bud

Sorry about posting the above question twice!. I'm keen to try the knitter switches. I have trawled around every supplier of components in the UK, and none of 'em has any stock.Does anybody know of a supplier - anywhere.Bud

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Guest

Peter,Have you used these switches? Are they any good?If so this looks like a cheap option compared with having to buy a rotary encoder board.Darren

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Guest PANTU

Hi All,using these rotary switches for all my rotary inputs (radio, etc)and they work very nicely, especially in combination with FSBus. But also a keyboard encoder would do.No need for decoder IC etc. Just to be used like a pair of switches which identify the direction of turn by itself.For around 4 bucks each, not a big deal either.@ Budyou got it right. Taking your example: Middle post to the common and the 8 to either left or right contact (depending on turn direction to represent) and the 9 to the other post.That

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Peter, You said that you can get these switches for about four bucks a piece. Could you tell me where you can find them for sale? I live in the Norhteast U.S. so someplace states side would be great, but any dealer that would sell them to an individual would be appreciated.Thanks, Rich

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Guest LeoL

I've been looking for inexpensive rotary switches myself and I've just ordered some from Digi-Key.I don't know if these are what you're looking for but the price is good.For about $4-$5 each depending on code type and with or without detents check out these: CT3001-ND, CT3002-ND, CT3003-NDOr for about $2.57 there's the P10859-ND, P10860-ND. I'm getting these since the output is easier to decode for my needs using an inexpensive PIC micro.Ooops, sorry prices are in Canadian dollars!-Leo

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Guest RichardL

Alright Peter. How about filing us in on how and where you got those Knitter switches. You have a bunch of guys out here foaming at the mouth over them!Richard

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Guest Bud

After trawling round loads of suppliers, I finally got through to the main Knitter Switch agents in the UK. They tell me that the Distributers listed on the K/S web site do not keep stocks of the components but they mat be able to supply me directly from the main UK Agency. The supply may depend on the number of units I want which could be unfortunate. Anyway I've asked for more info and some cost quotes and I'll see what happens. So far as I can see there does not appear to be a main agency in the USA.Bud

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Guest RichardL

Bud,I checked with Mouser and they could not help with the Knitter switch. Mouser also had no substitute within their supplier chain.Gee Bud, why don't help us all out and become a distributer! I could use eight. I'll be your first customer.Richard

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Guest Bud

RichardY' never know - it may come to that! I'm just waiting to see what is the minimum quantity the main UK Agency is prepared to sell.I'll post a note when the Sales Manager gets back to me. Was rather hoping that would be today but he hasn't. Maybe he's still laughing at my request for 20 !!Bud

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Guest RichardL

Hi Bud,Are you completely sure about these switches? Seems to good to be true. Am I correct in that:- you can rotate them clockwise or counter-clockwise.- they can be connected directly to an encoder board.- a key press is sent at every detent.- the clockwise key press can be different from the counter-clockwise key press.- they're inexpensive.Come on. Are we over-looking something?I'll up my order to ten if that helps.Richard

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Guest Bud

Richard,Know what you mean. This wasn't actually my call. See Peter's post of 21 Feb. I'm happy if he is !!Bud

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Guest PANTU

Hi Richard,those "Knitter" rotary switches are in fact Switches, NOT rotary Encoders. That makes the big difference and hence it is possible to connect them directly to a keyboard encoder (like 2 switches) . They act like 2 independant (but with 1 common contact, middle contact) keys (switches) whereby the direction detection is solved solely by a simple mechanical solution. Rotary encoders however deliver pulses which are phase shifted by 90 degrees and therefore need a decoder circuitry to identify in which direction you turn the knob. They are more precise but also more expensive and need additional electronics to make them work.Knitter sells them over here Germany even in small quantities.If you are going to order them keep in mind to order a few more as spare parts as they are basically made out of plastic and may get worn out sooner or later.Hope that is of some help.Best regardsPeter

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Guest RichardL

Hey Peter,Thanks for the information and your posting of the existance of such a switch. I would like to use them in an Airbus setup. Specifically, to change the altimeter, heading, speed, altitude, and vertical speed. Do you see any problems with using the Knitter switch for these functions? A few more questions if I may:- What do you mean by the Knitter switch not being a "precise" as a rotary encoder? The number of detents? Or does the Knitter switch skip if you rotate it to fast?- I know Bud has a quote in process, but do you know of any on-line suppliers that ship to the US? I didn't see any U.S. suppliers on the Knitter website.Thanks, Richard

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