Return-Path: Received: from [65.54.169.57] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.1.1) with ESMTP id 2538410 for flyrotary@lancaironline.net; Fri, 22 Aug 2003 11:10:18 -0400 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Fri, 22 Aug 2003 08:09:47 -0700 Received: from 65.141.112.87 by bay3-dav27.bay3.hotmail.com with DAV; Fri, 22 Aug 2003 15:09:47 +0000 X-Originating-IP: [65.141.112.87] X-Originating-Email: [lors01@msn.com] Reply-To: "Tracy Crook" From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: EC2 Tach output Date: Fri, 22 Aug 2003 11:11:37 -0400 Organization: Real World Solutions Inc. MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0098_01C3689E.27C5C5E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Message-ID: X-OriginalArrivalTime: 22 Aug 2003 15:09:47.0784 (UTC) FILETIME=[6D45D080:01C368BF] This is a multi-part message in MIME format. ------=_NextPart_000_0098_01C3689E.27C5C5E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Everything you ever wanted to know about the EC2 tach output. The tach output from the EC2 is an open collector output with a 2K = pullup to battery voltage (+12). It is a completely independant driver = so builders have the freedom to hook it up to any random place they want = to and blow it out without stoping the EC2 from functioning. Several = builders have exercised this freedom. Unfortunately, some of them have = used this same freedom on virtually every other EC2 connection with less = than good results. Due to the very few tachs that use 12 pulses /rev, I am dropping this = feature from future versions of the controller. Even Grand Rapids seems = to be dropping this option. A new Tach output may take its place with a = more common output pulse rate. The 24 tooth crank sensor (running at 1/2 crank speed) is the source of = the signal timing so it is 12 pulses per rev. This happened to be a = pulse rate option on the Grand Rapids EIS I was using so it worked out.=20 To answer the questions about EC2 software updates, I will be posting = details about when & how much (it's cheap) on the website. Tracy Crook, RWS ----- Original Message -----=20 From: Finn Lassen=20 To: Rotary motors in aircraft=20 Sent: Friday, August 22, 2003 12:56 AM Subject: [FlyRotary] Re: tach divider Might be an open collector output, in which case you'll need a pull-up = resistor. Just make sure you don't pull up to a higher voltage than what = Tracy's output chip is rated for. In my design I use a chip with SchmittTrigger input (for example = 74C14). Still would recommend a series resistor before the input to the = chip, and the input to the chip protected with a Zener diode (voltage = rated at less than max input rating of the chip and supply voltage). >Input - resistor - chip input -> | Z | >Ground-------------------------- For example, if you're supplying the chip with 12 Volts, use a 12V or = less Zener diode.=20 Size of resistor depends on type of chip, but for a 74C14, 10K or more = would be just fine. A capacitor in parallel with zener to filter out noise would also be a = good idea. 10,000 RPM x 12 / 60 =3D 2 KHz would be the maximum you'd ever need to = pass. A .047 uF capacitor and 10K resistor would be fine (3 KHz). Finn Haywire wrote: Hi Finn; You got me thinking that I could come up with a better solution, = than a voltage divider. I built the circuit on a breadboard again, but = using a capacitor across VDD & VSS this time. I tried various capacitors = and was unable to improve on the stability at higher voltages without a = voltage divider. I was considering ordering a couple of regulators = (still the best idea) when I started considering that I really don't = know anything about the output pulse from the EC2 other than it is a = 12pulse/rev signal. So I borrowed a Fluke scope from our shop and = brought it to the airport to have a look at the wave. It is a square = wave 768mV peak to peak, base voltage 8mV (I guess I could have just = asked Tracy :-). This surprised me as I was expecting 5V. In experiments = on the breadboard I found that the counter performed well at voltages up = to 20V as long as the clock input was not greater than 5 volts below = supply voltage. Now it's becoming a little more clear (remember, I'm = just an apprentice). When I showed the waveform to a journeyman at work, = he also was so surprised, he suspects it's not correct. Tracy can you = confirm this P/P voltage? The voltage divider, while being a little crude, is effective, = so I may just stick with that, unless I can find a couple of 5V = regulators in the spare parts. Since I expect that once the EM2 becomes = available, most builders will chose to use that since it really is a = great tool, so there won't be any reason to get too carried away with = this thing. Besides I'm just giving the darned things away because I had = 24 extra counter chips, so I shouldn't start buying parts -- no wonder I = can never save any money :-) John and Dave; I'll try to get a couple sent off before next week. John, I'll = need an address. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "Whatever you vividly imagine, Ardently desire, Sincerely believe = in, Enthusiastically act upon, Must inevitably come to pass".=20 -----Original Message----- From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net]On Behalf Of Finn Lassen Sent: Wednesday, August 20, 2003 5:41 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: some progress, and more understanding A capacitor accross the supply pins should be fine there. I was = thinking about the input. Of course if your input comes from Tracy's = controller, that's probably not an issue. But from anywhere else, like = coil pick up, some input filtering/clamping would be wise. Finn Haywire wrote: Hi Finn; It is a CMOS device capable of handling 20vdc on its VDD = pin. So I didn't feel it was necessary. In reality I found it was = unstable when VDD was less than 5vdc or greater than 11vdc, so since I = had a bag of 470ohm resistors handy, I just put a voltage divider on the = VDD. With a regulated 13.8vdc it gives me just under 7 volts and a = stable reading.=20 a side note; I originally had an internally regulated = alternator but the regulator failed (have since converted to an external = reg as per "electric Bob"). When running with the alternator tripped and = less than 12vdc, I found the tach would become erratic at high RPM's, = due to a low VDD. When alt is charging, everything is fine. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "Whatever you vividly imagine, Ardently desire, Sincerely = believe in, Enthusiastically act upon, Must inevitably come to pass".=20 -----Original Message----- From: Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net]On Behalf Of Finn Lassen Sent: Tuesday, August 19, 2003 8:23 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: some progress, and more understanding I don't see a Zener diode to clamp any spikes. Finn Haywire wrote: Attached are a couple of pics of my tach divider. It can be = set to divide by any number necessary. I can't guarantee it would work = with any tach but it works very well with my cheap = off-the-shelf-at-any-autoparts-store, Hastings tach. I have a few more = if anybody wants one. S. Todd Bartrim Turbo 13B RV-9Endurance C-FSTB http://www3.telus.net/haywire/RV-9/C-FSTB.htm "Whatever you vividly imagine, Ardently desire, Sincerely = believe in, Enthusiastically act upon, Must inevitably come to pass".=20 The EC-2 tach output has 12 pulses per revolution, and = won't directly work with any normal tach. Todd has made a divider to = bring the pulse rate down to normal, and it sounds like it's working = well. The TT that you have expects 1 pulse per rev, so if you don't = mind dividing the rpm reading by 12... :-) =20 ------=_NextPart_000_0098_01C3689E.27C5C5E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Everything you ever wanted to know = about the EC2=20 tach output.
 
  The tach output from the EC2 is = an open=20 collector output with a 2K pullup to battery voltage (+12).  It is = a=20 completely independant driver so builders have the freedom to hook it up = to any=20 random place they want to and blow it out without stoping the EC2 from=20 functioning.  Several builders have exercised this freedom. =20 Unfortunately, some of them have used this same freedom on = virtually=20 every other EC2 connection with less than good results.
 
Due to the very few tachs that use 12 = pulses /rev,=20 I am dropping this feature from future versions of the controller.  = Even=20 Grand Rapids seems to be dropping this option.  A new Tach output = may take=20 its place with a more common output pulse rate.
 
 The 24 tooth crank sensor = (running at 1/2=20 crank speed) is the source of the signal timing so it is 12 pulses per=20 rev.  This happened to be a pulse rate option on the Grand Rapids = EIS I was=20 using so it worked out. 
 
To answer the questions about EC2 = software updates,=20 I will be posting details about when & how much (it's cheap) on the=20 website.
 
Tracy Crook, RWS
 
 
----- Original Message -----
From:=20 Finn=20 Lassen
Sent: Friday, August 22, 2003 = 12:56=20 AM
Subject: [FlyRotary] Re: tach=20 divider

Might be an open collector output, in which case you'll = need a=20 pull-up resistor. Just make sure you don't pull up to a higher voltage = than=20 what Tracy's output chip is rated for.

In my design I use a = chip with=20 SchmittTrigger input (for example 74C14). Still would recommend a = series=20 resistor before the input to the chip, and the input to the chip = protected=20 with a Zener diode (voltage rated at less than max input rating of the = chip=20 and supply voltage).

>Input - resistor - chip input=20 ->
           =20       |
       =20           Z
   =20             =20  |
>Ground--------------------------


For = example, if=20 you're supplying the chip with 12 Volts, use a 12V or less Zener = diode.=20

Size of resistor depends on type of chip, but for a 74C14, 10K = or more=20 would be just fine.

A capacitor in parallel with zener to = filter out=20 noise would also be a good idea.

10,000 RPM x 12 / 60 =3D 2 KHz = would be=20 the maximum you'd ever need to pass.

A .047 uF capacitor and = 10K=20 resistor would be fine (3 KHz).


Finn

Haywire = wrote:
Hi=20 Finn;
    You got me thinking that I could come up = with a better=20 solution, than a voltage divider. I built the circuit on a = breadboard again,=20 but using a capacitor across VDD & VSS this time. I tried = various=20 capacitors and was unable to improve on the stability at higher = voltages=20 without a voltage divider. I was considering ordering a couple of = regulators=20 (still the best idea) when I started considering that I really don't = know=20 anything about the output pulse from the EC2 other than it is a = 12pulse/rev=20 signal. So I borrowed a Fluke scope from our shop and brought it to = the=20 airport to have a look at the wave. It is a square wave 768mV peak = to peak,=20 base voltage 8mV (I guess I could have just asked Tracy :-). This = surprised=20 me as I was expecting 5V. In experiments on the breadboard I found = that the=20 counter performed well at voltages up to 20V as long as the clock = input was=20 not greater than 5 volts below supply voltage. Now it's = becoming a=20 little more clear (remember, I'm just an apprentice). When I showed = the=20 waveform to a journeyman at work, he also was so surprised, he = suspects it's=20 not correct. Tracy can you confirm this P/P = voltage?
    The voltage divider, while being a little = crude, is=20 effective, so I may just stick with that, unless I can find a couple = of 5V=20 regulators in the spare parts. Since I expect that once the EM2 = becomes=20 available, most builders will chose to use that since it really is a = great=20 tool, so there won't be any reason to get too carried away with this = thing.=20 Besides I'm just giving the darned things away because I had 24 = extra=20 counter chips, so I shouldn't start buying parts -- no wonder I can = never=20 save any money :-)
 
John and Dave;
    I'll try to get a couple sent off before=20 next week. John, I'll need an address.
 

S. Todd Bartrim
Turbo 13B = RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

=   =20 "Whatever you vividly imagine, Ardently desire, Sincerely believe = in,=20 Enthusiastically act upon, Must inevitably come to pass". =

-----Original Message-----
From: Rotary motors = in=20 aircraft [mailto:flyrotary@lancaironlin= e.net]On=20 Behalf Of Finn Lassen
Sent: Wednesday, August 20, = 2003 5:41=20 AM
To: Rotary motors in aircraft
Subject: = [FlyRotary]=20 Re: some progress, and more understanding

A = capacitor=20 accross the supply pins should be fine there. I was thinking about = the=20 input. Of course if your input comes from Tracy's controller, = that's=20 probably not an issue. But from anywhere else, like coil pick up, = some=20 input filtering/clamping would be wise.

Finn

Haywire = wrote:
Hi Finn;
    It is a CMOS device capable of handling = 20vdc on=20 its VDD pin. So I didn't feel it was necessary. In reality I = found it=20 was unstable when VDD was less than 5vdc or greater than 11vdc, = so since=20 I had a bag of 470ohm resistors handy, I just put a voltage = divider on=20 the VDD. With a regulated 13.8vdc it gives me just under 7 volts = and a=20 stable reading.
    a side note; I originally had an = internally=20 regulated alternator but the regulator failed (have since = converted to=20 an external reg as per "electric Bob"). When running with the = alternator=20 tripped and less than 12vdc, I found the tach would become = erratic at=20 high RPM's, due to a low VDD. When alt is charging, everything = is=20 fine.
 

S. Todd Bartrim
Turbo 13B=20 RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

=   =20 "Whatever you vividly imagine, Ardently desire, Sincerely = believe in,=20 Enthusiastically act upon, Must inevitably come to pass". =

-----Original Message-----
From: Rotary = motors in=20 aircraft [mailto:flyrotary@lancaironlin= e.net]On=20 Behalf Of Finn Lassen
Sent: Tuesday, August 19, = 2003=20 8:23 PM
To: Rotary motors in = aircraft
Subject:=20 [FlyRotary] Re: some progress, and more=20 understanding

I don't see a Zener diode to = clamp=20 any spikes.

Finn

Haywire wrote:
Attached are a couple of pics of = my tach=20 divider. It can be set to divide by any number necessary. I = can't=20 guarantee it would work with any tach but it works very well = with my=20 cheap off-the-shelf-at-any-autoparts-store, Hastings tach. I = have a=20 few more if anybody wants one.
 

S. Todd Bartrim
Turbo 13B=20 RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm

=   =20 "Whatever you vividly imagine, Ardently desire, Sincerely = believe=20 in, Enthusiastically act upon, Must inevitably come to = pass".=20

 
The EC-2=20 tach output has 12 pulses per revolution, and won't = directly work=20 with any normal tach.  Todd has made a divider to = bring the=20 pulse rate down to normal, and it sounds like it's working = well.  The TT that you have expects 1 pulse per rev, = so if=20 you don't mind dividing the rpm reading by 12... =20 :-)
=

 



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