X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with ESMTP id 3637096 for flyrotary@lancaironline.net; Sat, 09 May 2009 15:14:37 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta02.mail.rr.com with ESMTP id <20090509191358113.NEKL19662@cdptpa-omta02.mail.rr.com>; Sat, 9 May 2009 19:13:58 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Cc: "'Oly Olson'" Subject: RE: [FlyRotary] Re: John Downings Tach Date: Sat, 9 May 2009 15:30:38 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcnQ1WeCU5u75P7tQImBoi5gPemgJgABwl5A In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20090509191358113.NEKL19662@cdptpa-omta02.mail.rr.com> Hi Bob, I don't have the part number and they have changed it from the one on my old Tach. However, I have a friend who just got one for his rotary from UMA and I am copying him on this e mail. Hi Oly, could you help us out by providing the UMA part number for your rotary tach Thanks Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Bob White Sent: Saturday, May 09, 2009 2:38 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: John Downings Tach Hi Ed, The 2 1/4 should fit OK. Do you have a part number for the one suitable for the rotary. I can't tell from their catalog. Otherwise, I will give them a call Monday. Thanks, Bob On Sat, 9 May 2009 10:32:55 -0400 "Ed Anderson" wrote: > Yes, UMA does have a tach version that works with the 2 rotor 13B - however, > if not digital they are all 2 1/4 or 3 3/8 size. John may have to go from 2 > 1/16 up to 2 1/4" to get what he wants. > > Ed > > Ed Anderson > > Rv-6A N494BW Rotary Powered > > Matthews, NC > > eanderson@carolina.rr.com > > http://www.andersonee.com > > http://www.dmack.net/mazda/index.html > > http://www.flyrotary.com/ > > http://members.cox.net/rogersda/rotary/configs.htm#N494BW > > http://www.rotaryaviation.com/Rotorhead%20Truth.htm > > -----Original Message----- > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On > Behalf Of Bob White > Sent: Saturday, May 09, 2009 10:07 AM > To: Rotary motors in aircraft > Subject: [FlyRotary] Re: John Downings Tach > > Hi Ed, > > Your analysis seems very detailed and accurate. The diagram was for the > tach that John was using. I modified it to work off the trigger signal > to one of the LS-1 coils. It was normally connected to the coil in a > distributor system so received 2 or 3 or 4 pulses per rev for a 4 or 6 > or 8 cylinder engine. Unfortunately it quit working. > > The plug wire triggered tach I was confused about was the UMA > recommended By Jeff. Since they used two plug wires as an input for > the 4 stroke 4 cylinder engine it had to be modified to read correctly > on his V6. If they had only used one plug wire for input, then the > number of cylinders wouldn't matter, except then they would have had an > incorrect reading on the 2 stroke engine. > > The original question was what tach will work with the rotary engine > without modification. It needs to fit a 2 1/16 inch hole and John > would rather have analog. I haven't found any great candidates yet. > The UMA should work, but it's digital. > > Bob W. > > > > On Sat, 9 May 2009 09:04:26 -0400 > "Ed Anderson" wrote: > > > Thanks, Bob - always appreciate the opportunity to learn. > > > > > > > > It appears from the diagram that this is a pulse integration type Tach > (I > > know you know that-just me thinking out loud). When a pulse is present at > > the base of Q1 it conducts - otherwise it's off. That the on and off > > conduction of Q1 corresponding to the ignition pulse rate causes the > voltage > > dropped across Q1 and therefore C1 to vary according - in part - to the > > resistor value selected designated by 4:6:or 8:. Apparently the 4: 6: and > > 8: are values referring to the number of cylinder the tach must be > initially > > set up for. > > > > > > > > Looking at the diagram, it does not appear to me that this tach diagram is > > designed to use a spark pulse from the ignition wire itself (as some > Tachs > > are). The reason I believe this is that if that were the case then the > tach > > would always get one spark per 720 deg regardless of 4,6 or 8 cylinders. > > The selection resistor would indicate to me that this Tach expects the > > "traditional" pulse set up. > > > > > > > > On a typical 4 stroke engine using one ignition coil each spark plug is > > fired once per 720 deg (Two revolutions). So if you have one coil > providing > > all the sparks and the signal is taken from the ignition coil rather than > a > > single spark plug wire, then the number of ignition pulses per crank > > rotation (360) is the number of cylinders divided by 2. So for the 4 > > cylinder 2 pulse per rev, for the six cylinder 3 pulses per rev and for > the > > 8 4 pulses per rev. This would seem to correspond to the 3 resistors > 4:6:8: > > shown on the diagram. Frequently the tach signal is taken from the > > negative lead of the single spark coil. > > > > > > > > That is probably the simplest case and was the case for most auto engines > > for decades. But now we have some engines with one coil for every 2 > > cylinders instead of a distributor, the coil fires two spark plugs at the > > same time, but one is a waste spark. A waste spark system would then fire > > once per crank revolution (360 deg)but sends out two sparks (one wasted) . > > Then some distributor-less 4 stroke engines use one ignition coil for > every > > spark plug, this ignition system fires each coil once for every 2 crank > > revolutions. So things have gotten a bit more complex relative to feeding > > the Tach. So between the 3 basic types of Tachs and the numerous > different > > ignition systems we have to day - it can get to be a mess. Especially > when > > documentation may be lacking > > > > > > > > > > > > In this case, it would appear resistor 8: (the highest resistance) is for > > the 8 cylinder as it would produce more sparks per unit time than a 4 > > cylinder for example and would therefore generate a higher voltage for > which > > needs to be reduced so that the meter reads the same rpm regardless of > > number of pulses. > > > > > > > > So I would presume that the 3 resistor values would then be selected along > > with the value of C1 to give a constant rpm (voltage level) regardless of > > the number of cylinders and pulses. This voltage in turn is reflected by > > the rpm meter's needle position. I would appear that the 200 ohm pot is > for > > making fine adjustments to this voltage driving the meter. > > > > > > > > At least that is the way it appears to me for an initial quick look. > > > > But, now I have forgotten what the original problem with the Tach was {:>) > > > > > > > > Ed > > > > > > > > > > > > > > > > Ed Anderson > > > > > > > > Rv-6A N494BW Rotary Powered > > > > > > > > Matthews, NC > > > > > > > > eanderson@carolina.rr.com > > > > > > > > http://www.andersonee.com > > > > > > > > http://www.dmack.net/mazda/index.html > > > > > > > > http://www.flyrotary.com/ > > > > > > > > http://members.cox.net/rogersda/rotary/configs.htm#N494BW > > > > > > > > http://www.rotaryaviation.com/Rotorhead%20Truth.htm > > > > > > > > > > > > -----Original Message----- > > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On > > Behalf Of Bob White > > Sent: Friday, May 08, 2009 10:52 PM > > To: Rotary motors in aircraft > > Subject: [FlyRotary] Re: John Downings Tach > > > > > > > > Hi John, > > > > > > > > Presumably I calibrated your tach to read one rpm per pulse. The > > > > attached schematic is similar to your unit. > > > > > > > > I changed some of the resistor values. I don't seem to have the actual > > > > values I used in my notes. Your tach also had a diode between the input > > > > and the junction of R2 and R3. I then connected it to a pulse > > > > generator and adjusted it for 1 pulse per rpm with the 200 ohm pot. > > > > With 100 pulses per second input, the reading should be 6000 rpm. I > > > > won't rule out the possibility that my calibration was in error. :) One > > > > possible cause of the failure is I may have over done the input > > > > reduction causing Q1 to fail. There is also a conditioning circuit > > > > between the coil trigger signal and the tach. It provides isolation > > > > and supplies a constant short pulse width signal. > > > > > > > > John, most of this is for Ed's benefit as I know you aren't an > > > > electronics guy. ;) > > > > > > > > Bob W. > > > > > > > > On Fri, 8 May 2009 21:09:56 -0400 > > > > "John" wrote: > > > > > > > > > Jeff, are you saying that with the one lead that the engine is actually > > > > > revving twice the reading. It is no wonder the plane goes over the > chocks > > > > > > > with a reading of 3,000 rpm before the tach quit working. It actually > > > > > starts jumping up and down before it makes the leap and I can get it > shut > > > > > down, that is why I tie it down good before I start it. JohnD > > > > > ----- Original Message ----- > > > > > From: "Jeff Whaley" > > > > > To: "Rotary motors in aircraft" > > > > > Sent: Friday, May 08, 2009 12:48 PM > > > > > Subject: [FlyRotary] Re: John Downings Tach > > > > > > > > > > > > > > > Hi Bob, the unit has 2 pick-ups, so with a 4/4 you need both coil > pick-ups > > > > > > > to get 2 pulses per rev, same as with the 2/2; if you had a 1 cylinder/2 > > > > > > stroke it would give 1 pulse per rev; therefore the number of cylinders > > > > > matter. With the V6, 2 pick-ups also produce 2 pulses per rev, but since > > > > > > they are occurring a slightly slower rates the frequency to voltage > > > > > conversion was not accurate; I changed the R/C filter on the input and > > > > > adjusted the internal reference pot to increase the rpm readout ... > drove > > > > > around for a few weeks with it in my Sonoma to verify calibration with > > > > > Sonoma Tach. The rpm max reading is 9999. > > > > > Jeff > > > > > > > > > > -----Original Message----- > > > > > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On > > > > > Behalf Of Bob White > > > > > Sent: Friday, May 08, 2009 12:18 PM > > > > > To: Rotary motors in aircraft > > > > > Subject: [FlyRotary] Re: John Downings Tach > > > > > > > > > > Hi Jeff, > > > > > > > > > > Thanks for the tip. There is something I don't understand about the > > > > > specs for this unit. It's good for 4 cylinder 4 stroke or 2 cylinder 2 > > > > > stroke. If I use the spark plug wire for the pickup, a 4 stroke > > > > > (piston) engine will see one spark per two rev. Why does it matter how > > > > > many pistons there are? If it's a wasted spark system, then one spark > > > > > per rev. just like a two stroke piston engine. There must be something > > > > > basic I don't understand. What sort of mod did it need for the V6? > > > > > > > > > > BTW, what is the maximum rpm reading for that unit? > > > > > > > > > > Thanks, > > > > > Bob W. > > > > > > > > > > On Fri, 8 May 2009 07:48:47 -0700 > > > > > Jeff Whaley wrote: > > > > > > > > > > > I like the belt and suspenders!! > > > > > > I am using a UMA digital tachometer 2 1/4" from Aircraft Spruce that > was > > > > > > > > originally designed for 4 cylinder engines using an electrical impulse > > > > > > > pickup from spark plug leads. I modified it to mate with the Ford V6; > I > > > > > > have modified it again to connect to the EC2 driving the R1 PRI > > injector. > > > > > > The rotary firing system is similar to a 4 cylinder so if this tach is > > > > > > > still available (Part # 10-24885) it would work off spark plug impulse > > > > > > > couplers. > > > > > > Jeff > > > > > > > > > > > > -----Original Message----- > > > > > > From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] > On > > > > > > Behalf Of Bob White > > > > > > Sent: Friday, May 08, 2009 12:14 AM > > > > > > To: Rotary motors in aircraft > > > > > > Subject: [FlyRotary] John Downings Tach > > > > > > > > > > > > John is using a standard tach that is normally connected to a > > > > > > distributor/coil ignition system. The straight 12V pulse used for the > > > > > > LS1 coils wouldn't activate it. I built an interface for him that > > > > > > involved taking that pulse as an input and generating a shorter > constant > > > > > > > > pulse width output. I modified the tach to trigger on the lower > voltage > > > > > > > > signal, and adjusted the scale factor to read correctly with one > > > > > > pulse/rev. As John reported, it worked for about 0.8 hours, then > quit. > > > > > > He is sending everything back to me so that I can find out where the > > > > > > problem is. I would like to find a tach solution that John can use > > > > > > without modifying anything. The parameters are he has a 2 1/16 inch > > > > > > mounting hole, the tach needs to read correctly with 1 pulse/rev > (would > > be > > > > > > the same as a two cylinder piston engine with coil and distributor), > > > > > > should trigger directly on a 12V pulse. > > > > > > > > > > > > I've found tachs on the web that mention working with distributorless > or > > > > > > > > electronic systems, but none of them were the 2 1/16 inch type. I > found > > a > > > > > > converter, the MSD 8913, but on the Summit Racing catalog it > > specifically > > > > > > says it won't work with the LS-1 system. It work by sensing the > current > > > > > > > > pulses to the 12V power lead on the coil. I don't know why it > wouldn't > > > > > > work with an LS-1 coil, but it doesn't seem like a good investment > when > > > > > > the LS-1 is specifically mentioned as not working. > > > > > > > > > > > > Can anyone recommend a tach solution that John can use with his LS-1 > > Coil > > > > > > rotary engine combination? > > > > > > > > > > > > On another topic, John has the only system I've heard of that has the > > > > > > capability to run on either EFI or a carburettor. John posted a > picture > > > > > > > > of his Tailwind a few days ago. It's a very good picture but > > considering > > > > > > the redundancy of the EFI/carb system, I felt that the picture was > > > > > > lacking. I submit this edited version as being more indicative of > > John's > > > > > > desire for uncompromised safety. > > > > > > > > > > > > Bob W. > > > > > > > > > > > > -- > > > > > > N93BD - Rotary Powered BD-4 - http://www.bob-white.com > > > > > > 3.8 Hours Total Time and holding > > > > > > Cables for your rotary installation - http://roblinstores.com/ > > > > > > > > > > > > -- > > > > > > Homepage: http://www.flyrotary.com/ > > > > > > Archive and UnSub: > > > > > > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > > > > > > > > > > > > > > > > > > > > > -- N93BD - Rotary Powered BD-4 - http://www.bob-white.com 3.8 Hours Total Time and holding Cables for your rotary installation - http://roblinstores.com/ -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com